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Patterns of Heredity

Name:______________________________________Period:____Date:____________

� _______all traits are simply inherited by dominant and recessive alleles (Mendelian

Genetics). In some traits, neither allele is dominant or many alleles control the trait.

Below are different ways in which traits can be inherited from parents to offspring.

5 Different Modes of Inheritance:

1. __________________________________:

• Definition: � Neither allele for a gene ___________________

� Phenotype of the heterozygous offspring will be a _________of the 2

homozygous parents.

• Ex: A ___________________white flower crossed with a

_________________red flower will produce all

_____________________pink flowers.

• Notation: � Alleles are all capital letters because NEITHER one _________________ the

other. So one of the alleles has a ____________( ‘ ) on it to represent an

alternate expression of the gene.

� Always make a _______to show the genotypes and the resulting phenotypes.

• Still supports Mendel’s Law of Independent Assortment

Ex. 1) In a certain species of flowers, snapdragons, the combined expression of both alleles for flower color produces a new phenotype-pink. A red snapdragon is homozygous and is crossed with a homozygous white snapdragon. What are the genotypic and phenotypic ratios of this cross?

Key:

P Cross = _________ x ________

Genotype: Phenotype:

Homozygous Parent

Homozygous Parent

Heterozygous OFFSPRING

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Ex. 2) Then cross the F1 generation and what are the genotypic and phenotypic ratios of this cross?

2. ________________________________

• Definition: o Both ______________are expressed ____________________

o Phenotypes of heterozygous offspring are

showing both traits!

� Ex: red cows crossed with white will

generate roan cows.

___________refers to cows that have

red coats with white blotches.

• Notation: o 2 ________________alleles (capital letters) are used

o Always make a _____ to show the genotypes and the resulting phenotypes Ex. 1) In chickens, black-feathered is not wholly dominant over white-feathered, so heterozygous chickens are black and white checkered. Cross two heterozygous chickens. What would the appearance of their offspring be?

Ex.2) In shorthorn cattle, the hybrid between red and white is called a roan. What phenotypes would result in the cross of a roan and a white?

Key:

Key:

Key:

P Cross = _________ x ________

P Cross = _________ x ________

P Cross = _________ x ________

Phenotypes:

Phenotypes:

Genotype: Phenotype:

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3. ________________________________

• Definition: o More than _______________for a single gene can control a trait.

• Multiple alleles must be studies by looking at the entire population of species.

• Each individual carries only 2 alleles for any gene (one on each homologous

chromosome).

o In this form of inheritance, a trait can have 1 gene, but ______________

for that gene.

• Ex: The human blood group can be any combination of A, B, and O

o The alleles are IA, IB, and i

� Alleles A and B are __________________________

� Alleles i (“O”) is ____________________________

• Notation:

o The possible genotypes/phenotypes:

o NOTE: the “i” is dropped from the genotype of A and B when the

______________________is written. (Genotype IAi is type ____ blood)

o Interesting facts:

� In the U. S., about 45% of the population is type O, 42% type A,

10% type B, and only 3% type AB.

GENOTYPES PHENOTYPES

Homozygous type A IAIA type ____blood

Heterozygous type A IAi type ____blood

Homozygous type B IBIB type ____blood

Heterozygous type B IBi type ____blood

Codominant type AB IAIB type ____blood

Recessive type O ii type ____blood

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Ex.1) If a person of blood group AB marries one belonging to group O, what could be the possible genotypes and phenotypes of their offsprings’ blood types? Ex.2) If a father is homozygous blood type A and the mother is heterozygous blood type B. What could be the possible genotypes and phenotypes of their offspring’s blood types?

� The positive and negative of a blood type is called

the__________________, it is a totally separate ________with

Rh+ (RR or Rr) and Rh–alleles (rr)

o If you have the protein = Rh +

o If you DO NOT have the protein = Rh –

� In the U. S., about 85% of the population is Rh+ and 15% Rh–.

� Thus the chances of someone being O- [having both ii and rr] would

be 45% × 15% = 6.75%.

� The most rare blood type would be _______, about 0.45% of the

population.

• _____is the universal donor

• ______is the universal receiver

P Cross = _________ x ________

Genotype: Phenotype:

P Cross = _________ x ________

Genotype: Phenotype:

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• 2 Types of Chromosomes:

1. _____________________- last pair of chromosomes—23rd pair for humans

XX = _________________

XY = _________________

2. ______________________________or _____________– all other pairs of

chromosomes – 1-22nd pair in humans

4.________________________: (X-Linked)

• Other genes besides the alleles for sex are located on sex chromosomes.

• Definition:

o These traits will occur _________frequently in males than females, such as

color blindness and hemophilia.

� WHY?

o Alleles for a gene may be present on the X chromosome but

_______on the Y. These are called sex-linked genes.

o This means that _________may inherit just ______allele for a

characteristic and that allele will be expressed, whether it is

dominant or recessive, because it is the ________allele present on

their X chromosome.

o X-linked traits most likely will be _______________to the normal

condition and the Y chromosome lacks the gene for a trait, so males

have a higher chance of having the disorder.

• These traits generally do NOT show up in ______________ since females have

genes on both their X chromosomes.

• Notation: o The alleles for these traits are written as ____________________on

the ____chromosome ONLY.

o ____ alleles are written on the Y chromosome!

� Ex: Colorblind male = XbY and Normal male = XBY

o _________________FEMALES are known as___________, XBXb

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Ex.1) Color blindness is a sex-linked trait that is caused by a recessive allele. A colorblind man marries a woman that is homozygous for normal vision.

� What possible types of vision could be found if they had boys? ____________________

� What possible types of vision could be found if they had girls? ____________________

Ex.2) A girl of normal vision, whose father was colorblind, marries a colorblind man. What types of vision could be found in their children?

5. _________________________________

• Traits are determined by ____________________

• They may or may not be found on the same chromosome

• Each gene may have more than 2 alleles

• The phenotypes may vary depending on the number of dominant and recessive alleles

in the genotype

• Traits that show _____________________are a result of polygenic inheritance

o Ex: eye color, skin color, height, facial features

Environment & Genes: • The____________________ can determine whether or not a gene is fully

expressed or expressed at all.

• Internal and external environments can affect phenotypes:

1. Influence of internal environment: ~ __________________based on sexes (testosterone, estrogen)

2. Influence of external environment:

~_____________________________

~_____________________________

~_____________________________

~_____________________________

~_____________________________

All of these can

influence the

expression of

genes.

P Cross = _________ x ________

Phenotype:

P Cross = _________ x ________

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Genetic Mutations:

How Genetic Mutations Can Affect The Human Body

Name: _______________________________________________Period:_________

The genetic information (DNA) in our cells plays a major role in how our body works. Spelling mistakes often happen when this information is being transcribed. When these spelling mistakes occur on uncoded

genes, there aren't any consequences. In a few rare cases, however, a spelling mistake – or mutation - can have serious implications.

Meet Ziad, Maria, and Nicholas. They all live with the consequences of mutations in their genetic code.

You will see that sometimes these mutations can cause an illness like diabetes, a handicap like colorblindness and even resistance to a disease like AIDS. Read each of these three scenarios and then describe in a few lines each person's daily life.

Scenario 1 - Ziad

Ziad was born with poor eyesight: he is color-blind. His mother genetically passed down this disorder to

him, and yet she does not suffer from color-blindness herself. How can that be? Well, Ziad's particular type of color-blindness (the inability to distinguish between red and green) is the most common kind and

is caused by a genetic defect on the x chromosome.

Since he can't rely on color to help him go about his daily activities, Ziad has to find other ways of coping. How do you think he manages? To help you answer this question, try to imagine what Ziad has to do to

dress himself properly, find the family car in a parking lot, identify insects for his collection or choose fresh fruit and vegetables at the grocery store.

Ziad’s daily life: ______________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

Scenario 2 - Maria

Maria suffers from diabetes. Because her pancreas doesn't produce insulin, Maria can't control the amount of sugar in her bloodstream. Insulin is very important because it helps our bodies efficiently use the energy in the food we eat and keeps our bodies in good working order.

Unfortunately, there is no cure for diabetes, but the disease can be controlled. To do so, Maria has to inject herself with insulin before each meal. She can never skip meals and she must always keep a few

healthy snacks on hand, especially before and after strenuous physical activity. Maria is a very active

teenager. She plays soccer twice a week after school and she also sings with the school choir twice a

week. At the moment she is planning a two-week family vacation to South America to visit her grandparents. What precautions do you think Maria has to take if she wants to do all these activities

without any difficulty?

Maria’s daily life: ______________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

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Scenario 3 – Nicholas

Nicholas has been a heroin addict for several years now. Despite his doctor's frequent warnings, Nicholas still shares needles with other heroin addicts. This is dangerous because when needles are shared, the contaminated blood of a person infected with the HIV virus, or other diseases, can be transmitted to

another person. The HIV virus can eventually cause AIDS, where a person's immune system breaks down

and they become highly susceptible to a range of illnesses, including some that can cause death. Currently there is no cure for HIV or AIDS.

One day, a friend Nicholas had shared needles with told him he had AIDS. Worried and convinced that he was infected too, Nicholas decided to get tested. He and his doctor learned that he had in fact contracted

the HIV virus. Several years went by and Nicholas still did not develop AIDS, so he and his doctor decided to do some more medical tests. The HIV virus can stay in the human body for several years without any

signs of illness: this is the HIV-positive period. The disease can show itself as early as two years after being infected by the HIV virus or as late as ten years. They discovered that Nicholas' genetic code

contained two mutant copies of a certain gene. Luckily, this mutation protects the cells against attacks by the HIV virus. Less than 1% of Caucasian, or white, males have this mutation. Thanks to this mutation,

Nicholas will spend the rest of his life without ever developing AIDS, although he will still be a carrier of the HIV virus and he could infect others.

In this case, the mutation had a positive effect on someone's health. Use your imagination to think up

beneficial genetic mutations that would make humans even better. You can use super-heroes like Superman as your inspiration.

Nicholas’s daily life: ____________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

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GENETIC CHANGES: MUTATIONS

Name:_________________________________________Period:_______Date:___________________

VOCABULARY: o ________________________= a random error or change in the DNA sequence that

may affect whole chromosomes or just one gene.

o _______________________= certain substances or conditions that can create a

greater rate of mutation

� Examples:

• Some _______________

• High temperatures

• ______________________

• Radiation

CHROMOSOMAL MUTATIONS: changes in chromosomes, usually during

meiosis when gametes are being made: 1. ___________________________= failure of homologous chromosomes to separate

during meiosis resulting in gametes (egg or sperm) with too few or too many

chromosomes.

� REMEMBER: Humans are ___________creatures; meaning for every

chromosome in our body, there is another one to match it.

� ________________= abnormal number of chromosomes. Ex: trisomy,

monosomy

MUTATIONS

Translocation

Inversion Insertion or Deletion

Nondisjunction Frameshift

mutation

Point

mutation

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• ____________________= zygote contains three copies of the

chromosome.

o Ex: Down syndrome, Klinefelter’s (XXY)

• _____________________= zygote contains only one

chromosome of the pair i.e. it is missing one chromosome

2. _____________________= occurs when part of a chromosomes is missing.

3. _____________________= occurs when a part of a chromatid breaks off and

attaches to its sister chromatid. The result is a duplication of genes on the same

chromosome.

4. ________________________ = Segment of chromosome breaks off and is

reinserted backwards (will flip upside down)

5. ______________________ = occurs when part of one chromosomes breaks off and is

added to a different chromosome.

GENE MUTATIONS: changes in the DNA sequence that will then change the

amino acid sequence. (Remember: Amino acids make up our proteins!)

1. __________________________= a change in a single base pair in DNA.

2. _________________________= error in the DNA sequence that adds or deletes a

single nitrogen base, causing nearly all amino acids following the mutation to be changed.

� Types:

• _______________________= One nitrogen base (A, T, C or G) is

deleted from the DNA sequence.

• ________________________= Extra nitrogen base is added to the

DNA sequence.

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Name:______________________________________Period:_____Date:_______

� ______________________= a valuable tool for anyone working in the field of genetics. • Used to show ____________________in families, and resemble a____________.

• Circles represent ______________, and squares represent ___________.

• __________________________are represented by roman numerals on the ______ side of the pedigree.

• _____________ is represented by a __________ through the symbol

• Lines that connect circles and squares horizontally represent that _____________________ has occurred.

• The further to the _____________an individual is the __________they are.

• Any vertical lines that drop down from the center of the above horizontal line show the ______________________ of the parents.

• We can then mark offspring that _____________or _______________exhibit certain

characteristics, such as eye color. Ex: The following pedigree shows family members with blue eye color.

• Brown eyes (B) are dominant over blue eyes. We can deduct the genotypes of some family members. Try to predict what the genotypes of the above family are for eye color.

A. What is the genotype of the mother? _______

B. What is the genotype of the son? _________

C. Can you deduce from the above information what the genotype of the father is? _______

How do you know? __________________________________________________________

I.

II.

I.

II.

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• Now let’s discuss the story of sickle-cell anemia. In Africa, there is a high incidence of malaria. Malaria is caused by a parasite that is transmitted by mosquitoes. The parasite feeds on the hemoglobin protein in red blood cells. If there is mutated strain of hemoglobin in the red blood cells, the parasite starves to death and dies. The picture on the left shows a sickled red blood cell and the picture on the right show a normal red blood cell. Persons who are homozygous for normal red blood cells easily die from malaria. Persons who are homozygous for mutated red blood cells usually do not die from malaria, but could die from complications resulting from their odd shaped red blood cells (sickle-cell anemia). Individuals heterozygous also usually do not die from malaria and are spared from the awful complications of sickle-cell anemia.

• Using the following information, design a pedigree chart and designate which of the family

members is homozygous for normal hemoglobin (HH), heterozygous (Hh), and homozygous recessive (hh).

~Mom-survived malaria ~Dad- died from complications from sickle-cell anemia at age 42. ~Son #1- survived malaria ~Son#2- Survived malaria, has sickle-cell anemia ~Daughter #1- survived malaria

• If the daughter marries a man who has normal hemoglobin (HH) in his red blood cells, what is the probability that their children will have sickle-cell anemia? ______ out of ______.

• Would their family be wise to take drugs that prevent a person from dying if infected with the malaria parasite? Why?

___________________________________________________________________________

I.

II.

Make A KEY: hh = Hh = HH =

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• Nearsightedness is a recessive trait (n). The shaded regions show individuals who are recessive for nearsightedness.

Now you construct a pedigree! Left-handedness (h) is a recessive trait.

Bill and Mary have a son, Mike, and daughter, Sue (youngest) that are right-handed. They also have a middle daughter, Marie that is a lefty. Sue gets married to John (righty) and has three children. Their oldest daughter, Sarah and their middle son, Joe are right handed. Yet, their youngest son, Ryan is a lefty.

1. Label the generations and label each individual in the pedigree by placing their name below the shape.

2. Determine the genotypes of as many individuals as possible.

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Human Karyotypes

I. What Is A Karyotype? • _________________________________ = a test to identify and evaluate the size,

shape, and number of chromosomes in a sample of body cells.

o Homologous chromosomes are arranged by ____________, ______________ patterns, and _____________________ placement.

o Extra, missing, or abnormal positions of chromosome pieces can cause problems with a person's growth, development, and body functions.

o 2 types of chromosomes:

� ___________________(autosomes) = chromosome pairs 1-22

� Sex = __________chromosome pair; determines the sex of the individual

o Examples:

II. Why Is It Done? 1) Determine whether the chromosomes of an adult have an ____________________that

can be passed on to a child.

2) Determine whether a chromosome __________________is preventing a woman from becoming pregnant or causing miscarriages.

3) Determine whether a chromosome defect is present in a fetus.

4) Determine the cause of a baby's birth defects or disability.

5) Identify the __________ of a person by determining the presence of the Y chromosome.

• This may be done when a newborn's sex is not clear.

III. How Is A Karyotype Created? 1) Human karyotypes are usually prepared from ____________________________of

chromosomes that have been spread, fixed, and stained to highlight banding patterns.

Normal __________ Normal __________

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2) The chromosomes in the photograph are ____________________ and then arranged in homologous pairs just as you will be doing in an upcoming activity.

3) Chromosomes are obtained through various tests: blood, bone marrow, amniotic fluid, or tissue from the placenta (the organ that develops during pregnancy to feed a growing baby).

• White blood cells are used most frequently because they are easily induced to divide and grow in culture.

• To test amniotic fluid, an _________________________________is done. A long needle is inserted through the abdomen into the uterus and amniotic fluid is withdrawn which contains cells shed by the fetus.

• A bone marrow specimen requires a bone marrow biopsy.

4) The sample is placed into a special dish and allowed to grow in the laboratory.

5) Various _______________ are added to stop the cell’s growth during prophase and metaphase.

6) The cells are placed on microscope slides and treated so they swell and their chromosomes spread apart.

7) Then various ______________ are used to highlight banding patterns.

8) The treated chromosomes can then be photographed, enlarged if desired, and ______ _______ to do a karyotype.

9) Experienced geneticists observe the karyotype for chromosomal abnormalities.

IV. What Are Genetists Looking For? 1) Differences in ____________ of chromosomes

• Missing pieces or additional pieces

2) Differences in the position of ________________________

• This is brought about by translocations.

3) Differences in basic ______________ of chromosomes

V. Common Abnormalities: 1) Down Syndrome (also known as

______________________)

• Cause = nondisjunction of the ______________of chromosomes

• Characteristics:

o Happens _____________ in males and females since it does not involve the sex chromosomes

o Individuals are mentally handicapped but the severity varies with the individual.

o The probability of giving birth to a child with Down syndrome ______________ with age of the mother, increasing significantly after age 35.

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2) Turner syndrome

• Cause = nondisjunction of the ______________________during meiosis so individuals are missing one copy of the ____chromosome.

o They have 22 pairs of autosomal chromosomes and only one X chromosome.

• Characteristics:

o Affects ONLY _______________

o Women are usually short, sexually underdeveloped and sterile.

o Women with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults.

3) Klinefelter syndrome (XXY)

• Cause = nondisjunction of the ____________________________during meiosis so individuals have an extra ___ chromosome

o The person has 22 autosomal chromosomes and 3 sex chromosomes (XXY).

• Characteristics:

o Affects ONLY ____________

o Males are often tall, sexually underdeveloped and may have slight intellectual impairment.

o Recognition of this syndrome before puberty usually does not occur.

o Many males with this syndrome function well within society and are not diagnosed until they are assessed for infertility as adults.

4) Jacob's syndrome (XYY)

• Cause = occurs when a male inherits ________ Y chromosomes from his father instead of one. The exact cause of why this occurs is unknown.

o Individuals with Jacob’s syndrome have 22 autosomal chromosomes and 3 sex chromosomes (XYY).

o He is an __________male. Remember most males are XY.

• Characteristics:

o Affects ONLY_______________

o The most common symptoms are learning problems at school and delayed emotional maturity.

o Males are tall, thin, have acne, speech problems, and reading problems.

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Codominance & Incomplete Dominance Practice Problems � Directions: Use a Punnett square to answer the following problems. Show all work to receive

full credit. You should include keys for you Punnett squares!

1. What is the difference between a trait that shows codominance and a trait that show

incomplete dominance?

2. How do you notate a Codominance Inheritance pattern?

3. How do notate an Incomplete Dominance inheritance pattern?

4. Nose size is a trait that exhibits incomplete dominance. Larger noses are not dominant over

small noses. If both parents have a medium size nose, do they have to worry about any of their

children having a large nose?

a. What are the genotypes of the parents?_______________________

b. List the genotypic & phenotypic ratios of the children below.

c. What % of this couple’s children will have large noses? _________________

5. Coat color is a trait that exhibits codominance. If a roan colored cow mates with a cow with a

white coat, what will the offspring look like?

a. What does the term “roan” mean?__________________________________

b. What are the genotypes of the parents? __________________________________

c. List the genotypic & phenotypic ratios of the offspring below.

Key:

Key:

18

6. Bark texture can be a codominant trait, producing trees with bark that is smooth, rough, or

both smooth/rough. If a rough barked tree pollinates a tree that is smooth/rough, will any of

the new saplings have smooth bark?

a. What are the genotypes of the parent tress?_____________________

b. List the genotypic & phenotypic ratios of the offspring below.

c. What % of the saplings will have smooth bark?____________________

7. A black haired female and a blonde male have four children, all of whom have brown hair.

a. What condition makes this possible?_________________________________

b. What are the genotypes of the parents?______________________________

c. What are the genotypes of the offspring?_____________________________

d. Are the parents heterozygous or homozygous?__________________________

e. Are the offspring heterozygous or homozygous?________________________

8. A florist has a big demand for pink carnations, so he breeds pink carnations in an attempt to

produce more pink carnations. However, when his new plants bloom, only 50% of the flowers are

pink. (The remaining 50% are red or white).

a. How did this happen? (show the Punnett square)

b. What must the genotypes of the parent plants be?______________________

c. What must the genotypes & phenotypes of the parent plants be in order for 100% of the

flowers to be pink? ___________________________

Key:

Key:

Key:

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SEX-LINKED TRAITS

Name:_______________________________________________Period:__________Date:__________

1. Use the key to determine the genotypes of the following people.

B = normal vision

b = colorblind

H = normal blood

h = hemophilia

a. Female w/ normal vision ____________

b. Male w/ normal vision ______________

c. Colorblind female ____________

d. Colorblind male ____________

e. Carrier of colorblindness ____________

f. Female w/ normal blood _________

g. Male w/ normal blood __________

h. Female w/ hemophilia _________

i. Male w/ hemophilia _________

j. Carrier of hemophilia _________

2. A woman who is colorblind marries a man with normal vision.

a. What are the genotypes of these parents?_________________________ b. Show the Punnett square below.

c. What are the genotypes and phenotypes of the offspring?

d. What % of the children will be colorblind? ______________

3. A man with hemophilia and a woman who carries the genes for the disease want to have children. a. What are the genotypes of these parents?__________________________ b. Show the Punnett square below.

c. What are the chances that their children could have hemophilia?________________________

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4. If a carrier female for hemophilia marries a normal male:

a. What are the genotypes of the parents?____________________________ b. Show the Punnett square below. c. What are the chances of the offspring having the disease hemophilia?_____________

d. What are the chances of their sons being normal?________________________ e. What are the chances of their daughters being carriers?____________________

5. If a woman’s father had hemophilia, what are the chances that she is normal? Assume that you do not know the mother’s phenotype.

6. If a woman’s mother was a carrier, what are the chances that she is normal? Assume that you do not know the father’s phenotype.

7. Are you more likely to be affected by a sex-linked disease if you are a male or a female? Explain why.

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Multiple Alleles

A. Blood types are an example of what type of inheritance?______________________________

B. In blood, the gene for type A and the gene for type B are______________________________.

C. The gene for type O is_____________________________. Directions: Using Punnett squares, determine the possible blood types of the offspring when: 1. Father is type O, Mother is type O

2. Father is type A, homozygous; Mother is type B, homozygous 3. Father is type A, heterozygous; Mother is type B, heterozygous 4. Father is type O, Mother is type AB 5. Father and Mother are both type AB

_______ % O

_______ % A

_______ % B

_______ % AB

_______ % O

_______ % A

_______ % B

_______ % AB

_______ % O

_______ % A

_______ % B

_______ % AB

_______ % O

_______ % A

_______ % B

_______ % AB

_______ % O

_______ % A

_______ % B

_______ % AB

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Mode of Inheritance

Define Notations Example

Neither allele for a gene dominates so

the hybrid phenotype is a

_____________of the homozygous

parents

• Alleles are all capital letters because _________________one dominates the other.

• One of the alleles has a prime ( ‘ ) on it to represent an alternate expression of the gene.

• A homozygous white flower is crossed with a homozygous red flower and produces all pink flowers.

• Blended trait is the ____________ KEY: Red = _________

White = _____________

Pink =_____________

Both alleles are

expressed _______________

• 2 _______________ capital letters (alleles) are used

• A black chicken is crossed with a white chicken and black and white checkered chickens are produced.

KEY: Black = _________

White = _________

Checkered = __________

More than 2 ______________for

a single gene can control a trait

• ______ & _____ are codominant o Use capital ”I”

with superscripts for specific allele

• ______ is recessive o Use lowercase

“i”

BLOOD TYPES • Type O = _______

• Heterozygous Type A = _______

• Homozygous Type A = ________

• Type AB = _________

• Heterozygous Type B = ________

• Homozygous Type B = ________

Traits are carried

on the _____chromosomes

• The alleles for these traits are written as superscripts on the _______chromosome ONLY.

• __________alleles are written on the Y chromosome!

COLORBLINDNESS,HEMOPHILIA

• Colorblind male = XbY

• Normal male = XBY

• Colorblind female = Xb Xb

• Normal female = XBXB, XBXb

• __________________ = XBXb

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DDiiffffeerreenntt MMooddeess ooff IInnhheerriittaannccee PPrroobblleemmss � Directions: Determine the possible genotypes and phenotypes for each cross. Be sure to use the

correct notation and create a genotype key when necessary.

1. Colorblindness is a sex-linked recessive trait (b). If a female carrier marries a male with normal vision, what are their chances of having a colorblind child? a. What type of inheritance makes this possible?________________________________

2. A cross between a homozygous red-flowered snapdragon and a homozygous white-flower snapdragon

produces all pink snapdragons. Complete the Punnett square for a cross between a pink snapdragon and a white snapdragon. a. What type of inheritance makes this possible?________________________________

3. A person that has type O blood marries a man that is heterozygous for type B blood. What are the

possible blood types of their children? a. What type of inheritance makes this possible?________________________________

4. A cross between a homozygous black chicken and a homozygous white chicken produces all back-

and-white checkered chickens. Complete the Punnett square for a cross between two checkered chickens. a. What type of inheritance makes this possible?________________________________

Key:

Key:

24

MUTATIONS ACTIVITY

Name:_____________________________________ Period:______Date:________________

Procedure: How do gene mutations affect proteins? CAREFULLY follow the directions below.

This is the ORIGINAL DNA STRAND: TAC GCC AGT GGT TCG CAC

1. Transcribe the original DNA strand into a strand of mRNA. Using the table provided, determine the order of amino acids that the original strand of DNA is coding for. The combination of these amino acids forms a protein fragment. Write out the amino acids in order.

DNA: ___________________________________________________________________________

mRNA: ___________________________________________________________________________

Amino Acids:_________________________________________________________________________

2. Change the fourth base in the original DNA strand from G to C. a. Write out your NEW DNA strand b. Transcribe this new DNA strand into its complimentary mRNA c. Decode the mRNA using the table provided and write out the amino acids in order d. Does the new protein fragment differ from the original one? Circle any differences.

DNA: ___________________________________________________________________________

mRNA: ___________________________________________________________________________

Amino Acids:_________________________________________________________________________ 3. Add a G to the original DNA strand after the third base.

a. Write out your NEW DNA strand b. Transcribe this new DNA strand into its complimentary mRNA c. Decode the mRNA using the table provided and write out the amino acids in order d. Does the new protein fragment differ from the original one? Circle any differences.

DNA: ___________________________________________________________________________

mRNA: ___________________________________________________________________________

Amino Acids:_________________________________________________________________________ Analysis:

1. When did a point mutation occur in the DNA strand? (Hint: what number of the procedure?)_______

2. When did a frameshift mutation occur in the DNA strand? (Hint: what number of the procedure?)_________

3. How did the point mutation affect the protein fragment? 4. How did the frameshift mutation affect the protein?

25

Genetic Changes: Mutations Worksheet Name:_______________________________________________Period:_______Date:____________ Complete the following outline using the words below: chemicals mutagens shift disorder mutation temperature frameshift mutation point mutation ultraviolet individual radiation variations

GENE MUTATIONS

I. 1. ______________________________________ is a permanent change in the genetic material of a cell. A. Mutations usually affect 2. __________________________________ genes. B. Mutations provide the 3. ______________________________ that are the basis of changes in a species. II. Mutations are often caused by 4. ________________________________, which are substances or conditions that cause or increase the rate of mutation.

A. Some viruses are mutagens. B. Very high 5. ____________________________ are mutagens. C. 6. ___________________________, such as pesticides and some food additives are mutagens. D. 7. _________________________________ is a well known mutagens. 1. X rays can damage DNA. 2. Gamma rays can damage DNA. 3. Large amounts of 8. ___________________________________ light can cause premature aging of the skin.

III. Mutation can occur in two basic ways. A. 9. ___________________________________ is one way. 1. This is an incorrect substitution of a single as in a codon of a gene. 2. It may not cause a noticeable difference. 3. It may cause a genetic 10. ______________________________. B. 11. ____________________________________ is another way. 1. This is when a nitrogen base is inserted or deleted and causes a 12. ___________________ of the genetic code. 2. This is generally more damaging than the mutation in IIIA.

26

Directions: In the following questions the boxes represent chromosomes. The chromosomes that are shaded grey are normal chromosomes and the chromosomes following the arrow a mutation has occurred. Identify each of the following types of chromosomal or gene mutations and briefly describe how it is different from normal chromosomes (shaded grey) and what might be the result of the rearrangement or abnormality.

13. Identification: ________________________________________________________________

14. Differs: _____________________________________________________________________

15. Possible results: ______________________________________________________________

16. Identification: ________________________________________________________________

17. Differs: _____________________________________________________________________ _________________________________________________________________________ 18. Possible Results: ______________________________________________________________

19. Identification: __________________________________________________________________ 20. Differs: _______________________________________________________________________ 21. Possible results: ________________________________________________________________ Directions: Define the conditions of the following terms. 22. nondisjunction __________________________________________________________________ _____________________________________________________________________________ 23. monosomy _____________________________________________________________________ 24. trisomy ________________________________________________________________________ 25. aneuploidy _____________________________________________________________________

1 2 3 4 5 6 7 1 2 3 6 5 4 7

1 2 3 4 5

a b c d e

1 2 3 d e

a b c 4 5

1 2 3 4 5 6 7 1 2 3 6 7

4 5

27

Interpreting Pedigrees

� Phenylthiocarbamide (PTC) gene- Can you taste it?

Background: In 1931, a chemist named Arthur Fox was pouring some powdered PTC into a bottle. When some of the powder accidentally blew into the air, a colleague standing nearby complained that the dust tasted bitter. Fox tasted nothing at all. Curious how they could be tasting the chemical differently, they tasted it again. The results were the same. Fox had his friends and family try the chemical then describe how it tasted. Some people tasted nothing. Some found it intensely bitter, and still others thought it tasted only slightly bitter. Soon after its discovery, geneticists determined that there is an inherited component that influences how we taste PTC. Today we know that the ability to taste PTC (or not) is conveyed by a single gene that codes for a taste receptor on the tongue. The PTC gene, TAS2R38, was discovered in 2003 on chromosome 7.The ability to taste the chemical phenylthiocarbamide (PTC) is dominant over the inability to taste it. Researchers use this discovery to help explain why some people love their leafy greens while others simply can’t bear the bitter taste. In one series of studies, PTC tasters were more sensitive to spicy and sweet foods and found fatty foods less appealing. They tended to avoid broccoli and grapefruit juice, found spicy food painful and shunned fat. Let’s test your tastebuds! ☺ Procedure A : Phenylthiocarbamide (PTC) gene 1) Obtain a piece of PTC paper from your teacher. Chew on the paper and then discard it.

a) If you are a PTC taster you should be able to taste the bitterness right away. Remember, if the paper tastes bitter that means you have the dominant trait but you may be homozygous (TT) or heterozygous (Tt). You don’t really know. For now, simply record T? on the line, if you could taste the paper. But if you cannot taste the paper, you have the recessive trait, so record “tt.”

Genotype: ______________

Diagram A: Pedigree showing individuals who cannot taste PTC. Directions: Answer the following questions using Diagram A.

1) What represents generations on a pedigree? __________________________________________

2) What represents males on a pedigree? ______________________________________________

3) What represents females on a pedigree? ____________________________________________

4) Who is the oldest in the 2nd generation? _____________

5) What is the relationship between individual I.-2 and III.-7? Be specific. ________________________

6) What is the genotype of individual I.-2? ____________

7) What is the genotype of individual II.-4? ____________

8) How would you notate that individual I.-1 died in the pedigree above?

7

6

1 2

3 4 5

I. II. III.

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Procedure B : Determining Genotypes From A Pedigree

1. Nearsightedness – or myopia – is a recessive trait. Use the symbols N and n to label the genotype for each of the numbered individuals. The shaded regions show individuals who are homozygous recessive for myopia.

Diagram B: Myopia (Nearsightedness)

2. Free ear lobes are a dominant trait. Attached earlobes are a recessive trait. Use the symbols E and e to label each of the numbered individuals. The shaded regions show individuals who are homozygous recessive for attached ear lobes. They exhibit the trait being studied; they have attached ear lobes.

Diagram C: Ear lobes

1 2

3 4 5

I. II. III. IV.

6

7 9 8 10

13 12 11

1 2

3 4

7 9 8 6 5

10

I. II. III. IV.

A) Free Attached

Ear lobes Ear lobes

29

Analysis: 1. If the genotype, “R?” is used, what does that genotype represent?

______________________________________________________________________________________

2. Why would someone conduct a pedigree study?

______________________________________________________________________________________

3. If you were to do a population study in Enola, where do you think you would find the LEAST amount of variation of phenotypes?

______________________________________________________________________________________

Going Further: A SEX-LINKED Pedigree Hemophilia is a disease in humans that causes the blood to clot slowly. It is a sex-linked trait that is caused by a recessive gene on the X chromosome. Label each of the numbered individuals Using H for normal blood clotting and h for hemophilia. Remember to label both the X and Y chromosome.

Diagram D: Hemophilia

I. II. III. IV.

1 2

3 4 5 6

7 8 9 10

11

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Pedigree Analysis Worksheet

Part A: Determining Genotypes in a Pedigree Gomez and Morticia Addams are expecting a new baby! They have come to your genetic counseling firm to find out the probability that he/she will have webbed feet, a trait that runs in the family.

1. Observe the following pedigree. Number the generations on

the pedigree.

2. Determine the genotypes of the individuals in the pedigree.

Write the genotypes on the pedigree.

3. Determine the probability that new baby Addams will have

webbed feet (recessive trait).

The Addams Family Pedigree for Webbed Feet B = normal feet b = webbed feet

� What is the probability that new baby Addams will have webbed feet? ________

Pugsley Wednesday ?????? New Baby Addams

Fester Gomez Morticia Cousin It

Mother Father Addams Addams

Grandpa Grandma Addams Addams

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Part B: Creating a Family Pedigree 1. Draw the following pedigree. Albinism (a) is a recessive trait.

John and Sally have a son, J.J. and daughter, Olivia (youngest) with normal pigmentation. They also have a middle son, Ethan that is an albino. Another couple, Dave and Judy have one son, Rob (oldest) and two daughters Beth and Becky with normal pigmentation.

Olivia from the first couple had three children with Rob of the second couple. Their son, Scott and one daughter, Abby have albinism. Yet, their youngest daughter, Mary, has normal pigmentation.

2. Label the generations and label each individual in the pedigree by placing their name BELOW

the shape.

3. Determine the genotypes of all the individuals and write the correct genotype INSIDE the

person’s symbol.

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Part C: Analyzing a Pedigree 1. Observe the following pedigree for tongue-rolling (T/t). Note: shaded individuals

cannot roll their tongues!

Answer the following questions:

1. The ability to roll the tongue into a U-shape is determined by a single gene. Determine if you can roll your

tongue. yes_______ no_______

2. Do any of the children in generation II have the same phenotype as their father? ______________

3. In which generation do children appear with the same phenotype as individual I-1? _______________

4. Look at the pedigree. Is tongue-rolling a dominant or recessive trait? Explain how you know.

5. Determine each individual’s genotype.

6. What is the relationship between individual I.-2 and III.-4? Be specific. _______________________

7. Individuals II-4 and II-5 have the same phenotype. Three of their children have the same phenotype,

but one, III-6, does not. What genotypes must individuals II-4 and II-5 be to produce children with

these phenotypes? Explain.

8. If individual II-5 married a woman who cannot roll her tongue, what is the probability that they would

have a child that could roll his/her tongue? ____________________

1 2

1 2 3 4 5

1 2 3 4 5 6 6

I. II. III.

33

REVIEW Packet: Patterns of Heredity

Name ____________________________________Period: ______Date:_____________ Part 1: MATCHING: Choose the best definition for each vocabulary term.

_____1. A diagram that shows how a particular trait is shown in a family A. autosomes

_____2. mutation that occurs when a segment of a B. aneuploidy chromosome breaks off and is reinserted backwards.

_____3. abnormal number of chromosomes C. pedigree

_____4. mutation that occurs when one chromosome of D. polyploidy a pair is missing _____5. More than one gene controlling a trait E. mutagen

_____6. Anything that can cause a mutation F. nondisjunction

_____7. Body chromosomes; pairs 1-22 G. frame shift mutation _____8. Error in DNA that adds or deletes a single H. Gregor Mendel base that causes all following amino acids to be affected I. translocation

_____9. A chart where the chromosomes are arranged in their homologous pairs J. trisomy

____10. Failure of homologous chromosomes to K. inversion separate during meiosis

L. polygenic inheritance ____11. “Father of Genetics”

M. karyotype ____12. Piece of one chromosome breaks off and joins another chromosome N. monosomy

Part 2: FILL-INS: Complete the following with the best word or words. You may use the words more than once.

Polygenic Inheritance Codominance Sex-linked trait Incomplete Dominance Sex Chromosomes XX Multiple alleles XY

1. Some genes are located on sex chromosomes. A ____________________________ is a trait controlled by these genes.

2. Traits controlled by more than TWO ALLELES are said to have ___________________________ 3. ___________________________________are chromosomes that determine the sex of an individual. 4. What are a normal male’s sex chromosomes?______________________________ 5. What are a normal female’s sex chromosomes? ______________________________ 6. What type of inheritance pattern would the heterozygous offspring be a blend of the two homozygous

parents?___________________________________ 7. When the phenotypes of hybrid offspring are showing both traits and NO blending occurs, what type

of inheritance pattern would this be?____________________________ 8. What type of inheritance pattern would you use a prime (‘) to notate the alternate form of an

allele?________________________________

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Part 3: COMPLETION: Answer the following questions concisely. 1. How do you notate sex-linked traits? 2. How do you notate codominant traits? 3. What trait is an example of multiple alleles? 4. What would be an internal factor that can influence gene expression? ______________________

5. What are some environmental (external) factors that can influence gene expression? 6. In sex-linked traits, how would a carrier genotype be written? ______________________

7. Why do sex-linked traits occur more often in males than females? 8. Describe how a karyotype is created? Part 4: MODES OF INHERITANCE: Read the following problems carefully. If need complete a Punnett square and answer the questions. Be sure to use the correct notation of genotypes. ______1. When roan cattle are mated, 25% of the offspring are red, 50% are roan, and 25% are white.

Upon examination, it can be seen that the coat of a roan cow consists of both red and white hairs. This trait is one controlled by_____________________.

A. Sex-linked genes C. Incomplete dominance B. Multiple alleles D. Codominance

______2. What type of inheritance is shown when a red-flowering plant is crossed with a white-flowering plant and only pink-flowering plants are produced?

A. Inbreeding C. Incomplete dominance B. Polygenic inheritance D. Codominance

35

3. A cross between a homozygous red-flowered snapdragon and a homozygous white-flower snapdragon produces all pink snapdragons. a. What type of inheritance makes this possible?________________________________ b. How do you know?_______________________________________________________________ c. Complete the Punnett square for a cross between two pink snapdragons. What are the possible genotypes

and phenotypes of the offspring? Be sure to use the correct notation. 4. A cross between a homozygous black chicken and a homozygous white chicken produces all back-and-white

checkered chickens. a. What type of inheritance makes this possible?________________________________ b. How do you know?_______________________________________________________________ c. Complete the Punnett square for a cross between a white and checkered chicken. What are the possible

genotypes and phenotypes of the offspring? Be sure to use the correct notation.

5. Colorblindness is a sex-linked recessive trait (b). If a female carrier marries a colorblind male, what are their chances of having a colorblind daughter? Be sure to use the correct notation.

6. A person that has type O blood marries a man that is heterozygous for type A blood. What are the possible

phenotypes of their children? Be sure to use the correct notation. a. What type of inheritance is human blood types an example of?____________________________

7. A person that has type AB blood marries a woman that is homozygous for type B blood. What are the possible

phenotypes of their children? Be sure to use the correct notation. 8. Many genes control skin color. What type of inheritance pattern makes this possible? ________________

Key:

Key:

36

Part 5: PEDIGREES: Having dimples is dominant (D) to not having dimples (d). The pedigree chart illustrates the inheritance of not having dimples. Determine the genotypes of the family and use the chart to answer the questions.

1 2

3 4 5 6

7 8 9 10 11

1. Place the correct genotype on the lines below each symbol.

2. How many generations are represented?______________________________

3. What is the relationship between individual I-2 and III.-8? Be specific!________________________ 4. What is the genotype of individual II.-3? _________________

a. How do you know? 5. What is the genotype of individual III-10? _________________

a. Why? 6. Individual 11 does not have dimples, yet his father has dimples. Explain how this is genetically

possible. 7. If individual 7 marries a woman who does not have dimples, what are their chances of having a child

with dimples?

I.

II

III..

37

Unit Learning Map (19 days): Patterns of Heredity Mrs. Hostetter

Class: Biology B – PA Standard: 3.3.10: Describe how genetic information is inherited and expressed. Explain the different types of inheritance.

Unit Essential Question(s): Optional

Instructional Tools:

Making a Baby Activity Genetic Disorder Research

project Karyotype Activity

Pedigree Project CSI Activity

How can you explain the different types of inheritance patterns?

Incomplete dominance & Codominance

Multiple Alleles & Sex-linked crosses

Mutations & Genetic disorders

Tools: Karyotypes & Pedigrees

What is the difference between incomplete

dominance and codominance crosses?

What is the difference

between multiple alleles and sex-linked

crosses?

How can a mutation

affect the production of a protein?

How are karyotypes

and pedigrees used to help scientists identify

genetic traits?

Incomplete dominance Codominance

Multiple alleles Polygenic inheritance Sex-linked crosses Sex Chromosomes Autosomes

Mutation Mutagen Nondisjunction Aneuploidy Trisomy Monosomy Deletion Insertion Inversion Translocation Point mutation Frameshift mutation

Karyotype Down Syndrome Turner Syndrome Klinefelter Syndrome Jacob’s Syndrome Pedigree Carrier

Vocabulary: Vocabulary: Vocabulary: Vocabulary:

Lesson Essential Questions: Lesson Essential Questions: Lesson Essential Questions: Lesson Essential Questions:

Concept Concept Concept Concept

38

Patterns of Heredity Vocabulary:

1) Incomplete dominance = neither allele for a gene dominates � Notation:

• Alleles are all capital letters because NEITHER one dominates the other. So one of the alleles has a prime ( ‘ ) on it to represent an alternate expression of the gene.

2) Codominance = both alleles are expressed equally � Notation:

• 2 different alleles (capital letters) are used

3) Multiple alleles = more than 2 alleles for a single gene can control a trait; example = blood types

4) Polygenic inheritance = traits are determined by many genes

5) Sex-linked crosses = traits are carried on the sex chromosomes � Notation:

• The alleles for these traits are written as superscripts on the X chromosome ONLY. • No alleles are written on the Y chromosome!

� Ex: Colorblind male = XbY and Normal male = XBY

6) Sex chromosomes = last pair of chromosomes—23rd pair for humans; XX = female; XY = male

7) Autosomal chromosome or Autosomes = chromosomes pairs 1-22 for humans

8) Mutation = a random error or change in the DNA sequence that may affect whole chromosomes or just one gene

9) Mutagen = certain substances or conditions that can create a greater rate of mutation

10) Nondisjunction = failure of homologous chromosomes to separate during meiosis resulting in gametes (egg or sperm) with too few or too many chromosomes

11) Aneuploidy = abnormal number of chromosomes. Ex: trisomy, monosomy

12) Trisomy = zygote contains three copies of the chromosome

13) Monosomy = zygote contains only one chromosome of the pair i.e. it is missing one chromosome

14) Deletion = occurs when part of a chromosomes is missing.

15) Insertion = occurs when a part of a chromatid breaks off and attaches to its sister chromatid. The result is a duplication of genes on the same chromosome

16) Inversion = Segment of chromosome breaks off and is reinserted backwards (will flip upside down)

17) Translocation =occurs when part of one chromosomes breaks off and is added to a different chromosome

18) Point mutation = a change in a single base pair in DNA

19) Frameshift mutation = error in the DNA sequence that adds or deletes a single nitrogen base, causing nearly all amino acids following the mutation to be changed

20) Karyotype = a test to identify and evaluate the size, shape, and number of chromosomes in a sample of body cells

39

21) Down syndrome = also known as trisomy 21 � Cause = nondisjunction of the 21st pair of chromosomes � Characteristics:

• Happens equally in males and females since it does notinvolve the sex chromosomes • Individuals are mentally handicapped but the severity varies with the individual • The probability of giving birth to a child with Down syndrome increases with age of the

mother, increasing significantly after age 35

22) Turner syndrome = � Cause = nondisjunction of the sex chromosomes during meiosis so individuals are missing one

copy of the X chromosome. • They have 22 pairs of autosomal chromosomes and only one X chromosome.

� Characteristics: • Affects ONLY females. 4 • Women are usually short, sexually underdeveloped and sterile. • Women with this syndrome function well within society and are not diagnosed until they are

assessed for infertility as adults.

23) Klinefelter syndrome = (XXY) � Cause = nondisjunction of the sex chromosomes during meiosis so individuals have an extra X

chromosome • The person has 22 autosomal chromosomes and 3 sex chromosomes (XXY).

� Characteristics: • Affects ONLY males. • Males are often tall, sexually underdeveloped and may have slight intellectual impairment. • Recognition of this syndrome before puberty usually does not occur. • Many males with this syndrome function well within society and are not diagnosed until they

are assessed for infertility as adults.

24) Jacob's syndrome = XYY � Cause = occurs when a male inherits two Y chromosomes from his father instead of one. The exact

cause of why this occurs is unknown. • Individuals with Jacob’s syndrome have 22 autosomal chromosomes and 3 sex

chromosomes (XYY). • He is an XYY male. Remember most males are XY.

� Characteristics: • Affects ONLY males. • The most common symptoms are learning problems at school and delayed emotional

maturity. • Males are tall, thin, have acne, speech problems, and reading problems

25) Pedigrees = a valuable tool for anyone working in the field of genetics 26) Carrier = Heterozygous FEMALES; XBXb