Genetics Genetics-___________________ Heredity-passing of traits

from __________________________

Trait- ____________________that can be passed on to

offspring ex: hair color, eye color, etc

Genes! Genes- _____________________

___________________________ __________________________ .

There are _________ of genes on each chromosome.

DNA chromosome gene protein trait

What Determines Traits?

Genes

Some traits are coded for by one gene which codes for one protein causing a trait. i.e. freckles, earlobe attachment, etc

protein

Polygenic Inheritance – When a Single Trait is Influenced by Many Genes

Height is a polygenic trait

Polygenic traits – ______________________________ _____________________________________________.

More than one gene = more than one protein that causes the trait so complex variation in that trait

Hand span, height, eye color, etc.

Chromosomes Homologous chromosomes-

________________________________________________________________________________________________________

One of each pair from Mom and one from Dad

Each human somatic (body) cell has _________ of homologous chromosomes

Other species have different numbers.

homologous chromosomes

Passing of One Gene Remember that during meiosis when we make

gametes (egg and sperm) the genetic material is cut in half.

Egg and sperm each only have ________________ because these gametes only get ONE copy of every chromosome (haploid).

When gametes come together during fertilization, it forms the baby with a complete set of chromosomes and ________________________ (_________).

Homologous Chromosomes

_____ contributed one and _____ contributed other of each pair of homologous chromosomes in our somatic cells.

Therefore, we received _______________ from each of our parents

This means each somatic cell has ________________ ____, and therefore, ______________.

Alleles Alleles - ________________________________

F allele codes for freckles f allele codes for no freckles

Allele for freckles--F

Allele for no freckles—f

Position on chromosomes where freckle presence gene is located

Genotype vs. Phenotype

Genotype- ______________________________________ Written as _________-one copy from each parent _________________

Phenotype- ____________________________________________

Written as _______________ Freckles or no freckles

***Phenotype = Genotype + Environment

Genotypes

_______________________ - (purebred) receiving two identical alleles for a particular trait from your parents. i.e. Freckle presence gene Alleles F=freckles and f=none Homozygous: FF or ff

______________________ - (hybrid) receiving two different alleles for a particular trait from your parents Heterozygous: ________?

F F F f f f

Mom Dad Mom Dad Mom Dad

Possibility #1 Possibility #2 Possibility #3

What About the Heterozygous Genotype?

FF genotype = ____________ phenotype? ff genotype = _____________phenotype? What about Ff phenotype? As it turns out, the allele coding for freckles, F,

___________________ the alleles coding for no freckles, f. The heterozygous genotype, Ff, results in

________________ ____________

_________________– form of trait that overcomes others and written as a ____________________________________- of trait that is hidden in the presence of a dominant one and written as a __________________

F F F f f f

Mom Dad Mom Dad Mom Dad

Genotype Example Phenotype

Homozygous Dominant

Freckles

No freckles

Heterozygous

So What? How can we use this information on meiosis

and genetics? If we know parents’ genotypes, we can figure

out the genotype possibilities of their children. It can be used to determine how likely you and

your spouse are to have children with freckles, their blood type, or the possibility of passing on a disease to them among other things.

Genetics Predictions To determine possible genotypes

of offspring, we use ______________________

Punnett squares -figures used to determine ___________________ ___________________________ based on the parents’ genotypes.

For example, if you crossed two heterozygous parents who have freckles, would their kids all have freckles, just some, or none at all?

Parent #2gametes

Parent #1gametes

How To Make a Punnett Square for a One-Factor Cross or Monohybrid Cross

Write the genotypes of the two organisms that will serve as parents in a cross.

In this example we will cross a male and female osprey that are heterozygous for large beaks.

They each have genotypes of Bb.

1 3

2 4

Practice

Trait: Number of fingersAlleles: F or f ____________: F codes for polydactyly so person has more than 5 fingers or toes.

_____________: f codes for normal five fingers or toes

Genotype Example Phenotype

Homozygous Dominant

FF

Homozygous Recessive

Five fingers

Heterozygous

Use a Punnett square to cross a normal parent with a heterozygous parent.

What are their chances of having a child with polydactyly?

Rules of Genetics

Early Ideas - Heredity►We know about genetics

because an Austrian monk named _______________ decided to run experiments on pea plants.

►Father of genetics►It was originally believed a

child’s traits were result of “blending” between parent’s traits

►Nothing was known about DNA!

Mendel’s Pea Plants

Why did Mendeluse pea plants?1. Peas ________________

___________________ ___________________ he could observe easily

2. He understood their method of reproduction3. They reproduced quickly

Characters investigated by Mendel

Reproduction in Plants

• Plant cells undergo meiosis, just like animals, to create plant gametes– Plant sperm =pollen – Plant egg = ovule

Reproduction in Plants• ____________

– Pollen released – Pollen fertilizes the

ovules– ____________________

___________. • Mendel could control

how plants were fertilized because he understood this process

• Pollination Animation

Genotype vs. Phenotype

►One trait Mendel followed through many crossed of peas was peas shape.

►Alleles:– ______________– ______________

Mendel’s Experiments

►____________________(P) “original” group mated

►________________(F1) offspring of the parental cross

►_________________(F2) offspring of crossing two F1 plants

Mendel’s First Experiment• Wanted to know what would

happen if cross 2 plants with different forms of a trait.

• The 1st thing Mendel did was cross 2 _____________ (homozygous) plants as the _______________________(P).

?

Results of the Cross?

►In F1 generation _____________resulted.

►What happened?►Round _____________ over wrinkled ►Do a Punnett square to show the

results he should have gotten.ALL ROUND F1

Principle of Dominance

►Round allele (R) dominated over wrinkled form of the gene (r)►Rule #1: .

one allele can dominate so trait coded by other allele hidden. – i.e. R dominates over r when both present– Because we know this, we

represent the round allele with a capital R.

Mendel’s 2nd Experiment

►Mendel extended his experiment and crossed two of his F1 plants…

►Do a Punnett square to show what results he should have gotten.

?

Results?

►After crossing two F1 plants, _________________, some F2 generation offspring showed recessive trait, some the dominant trait

►________(round: wrinkled)►25% wrinkled, 75% round►The wrinkle trait showed up

again.

Mendel’s Conclusions• - when gametes form, the two

copies of our genes are separated so each parent gives only one in their egg or sperm

• This gave us the idea of meiosis and how gametes are formed!

gametes

R or r

meiosis

R or rgametes

meiosis

Pea Parent 1: Pea Parent 2:RrRr

Mendels Conclusions cont.►Does everyone with brown hair have blue eyes?►Does everyone with freckles have a big nose? ►NO!►Mendel’s - inheritance of

one trait will not affect inheritance of another. Traits most of the time are not “_______” together!

►He saw pea plants with round peas and purple flowers, and pea plants with round peas and white flowers.

Mendel Video:

Independent Assortment

Mendel wondered if the _____________________ ______________another pair.

Mendel performed an experiment that followed two different genes as they passed from one generation to the next.

Because it involves two different genes, Mendel’s experiment is known as a _____________________. Single-gene crosses are ___________________.

The Two-Factor Cross: F1

Mendel crossed true-breeding plants that produced only round yellow peas with plants that produced wrinkled green peas.

The round yellow peas had the genotype RRYY, which is homozygous dominant.

The wrinkled green peas had the genotype rryy, which is homozygous recessive.

All of the F1 offspring produced round yellow peas. These results showed that the alleles for yellow and round peas are dominant over the alleles for green and wrinkled peas.

The Punnett square shows that the genotype of each F1 offspring was RrYy, ____________ ___________________________.

The Two-Factor Cross: F2

Mendel then crossed the F1 plants to produce F2 offspring.

Mendel observed that 315 of the F2 seeds were round and yellow, while another 32 seeds were wrinkled and green—the two parental phenotypes. 

But 209 seeds had combinations of phenotypes, and therefore combinations of alleles, that were not found in either parent.

The alleles for seed shape segregated independently of those for seed color.

Genes that segregate independently—such as the genes for seed shape and seed color in pea plants—do not influence each other’s inheritance.

Mendel had discovered the principle of independent assortment.

______________________________________________________________________________________________________________________________________________________________________________________________________

Genetics Rules

►Rule #1: Dominance►Rule #2: dominance -some alleles aren’t

completely dominant so they BLEND ►Rule #3: -some alleles dominate

together so BOTH ARE SEEN►Rule #4: -ALL alleles on a male’s X

chromosome (X-linked) are expressed.

Complete Dominance

►Rule #1: Some alleles _________________ over others:– B= brown eyes– b=blue eyes– Bb= brown eyes, so B is

completely dominant.– One allele capital, the

other lower case

Incomplete Dominance

►Rule #2: Some alleles _______________________, so they ____________:– R= red flowers– R = white flowers– Rr = pink flowers– One allele capital, the other

lower case

PINK FLOWERS!!! BLENDING!!!

Codominance►Rule #3: Some alleles __________________ so they

BOTH are shown– H = brown hair on horses– H’ = white hair on horses– HH’ = both brown and white hairs, so the horse is roan

color.– Blood types are like this, too.

Antigens-markers on cells

Blood type determined by your markers on your red blood cells

4 blood group phenotypes:Type A has A antigens

Type B has B antigens

Type AB has A and B antigens

Type O has no antigens

Blood Types

Multiple Alleles

Multiple alleles- 3 different forms of the gene code for blood types IA, IB, and i– Allele IA codes for “A”

antigen – IB codes for “B” antigen– i codes for none

Multiple Alleles

• 6 blood group genotypes• ___________________-

IA and IB dominate over i• ____________- IAIB

genotype shows BOTH A and B antigens

• Both alleles that codominate are written with capital letters!

Blood Types►Your body’s immune systems creates antibodies

against anything foreign– Antibodies-proteins produced by your immune system

to fight off things that look “foreign.”►Type A--makes anti-B antibodies►Type B--makes anti-A antibodies►Type AB--makes NO antibodies— universal receiver►Type O--makes anti-A and anti-B antibodies—

universal donor

Sex-Linked Genes

►Rule #4: sex-linked genes: ALL alleles on a male’s X chromosome (X-linked) are expressed.– Male sex chromosomes?

_________– Female sex chromosomes?

_________– We also call sex-linked genes by

another name, X-linked, because the X chromosome has the majority of the genes.

Sex-Linked Genes

► In males, EVERY gene on their X chromosome is expressed. The Y doesn’t have the same genes.

► In females this is not the case because they have another copy on their other X chromosome to overcome it.

Genes: _____ _____ _____ ___

Sex-Linked Genes

►Examples of sex-linked disorders:– Colorblindness

– Hemophilia– Fragile X Syndrome– Duchene Muscular Dystrophy – Cleft Palate– Vitamin D Resistant Ricketts– 3 types of deafness– Male Pattern Baldness

X-linked recessive disorder

Sex-Linked Genes►Genes that occur on sex

chromosomes are written with X’s and Y’s to show this special situation.– I.e. red-green colorblindness is a

recessive trait. It is found on the X chromosome, not the Y.

– We write the alleles this way:►X¢ = colorblindness►XC = normalThe slash indicates it is a lower case

letter so there is no confusion

Sex-Linked Genes

►Try to complete this table:

PhenotypesPhenotypes GenotypesGenotypes

Normal MaleNormal Male

Colorblind MaleColorblind Male

Normal FemaleNormal Female

Normal Normal ““carriercarrier”” FemaleFemale

Colorblind femaleColorblind female

What is a Karyotype? Karyotype- __________

____________________ in a somatic cell.

46 chromosomes in a normal, human karyotype 23 pairs of

homologous chromosomes – pairs of chromosomes with similar structure and function

Amniocentesis Method for obtaining fetal cells

from fluid surrounding fetus. Chromosomes can be obtained

from these cells for a karyotype.

This is a “risky” procedure. Should ONLY be performed on

women who:a) Are in their mid 30’s or older.b) Have had a previous child

with a chromosomal defect.

What can be determined from looking at a

karyotype?

_____________________ Autosomes-all

chromosomes except sex chromosomes

Sex chromosomes -either XX (female) or XY (male)

_____________________

Two Types of Mutations Gene mutation- ___________________________________ Chromosomal mutation- ____________________________

__________________________________________ Either type of mutation can involve autosomes

(chromosomes 1-22) or sex chromosomes (X & Y)

Gene Mutations Gene mutation- single gene

defective _____________ _____________ _____________

Insertion

Deletion

Subtitution

Chromosomal Mutations

Chromosomal mutation- missing or extra entire chromosome and ALL its genes ___________—having one less chromosome

(45) ___________—having an extra chromosome

(47) ___________—missing part of a chromosome

Autosomal Disorders _________________- disease involving the 22

pairs of chromosomes that are NOT sex chromosomes (X,Y) and any genes on them.

Can result from Gene mutation: defective gene

on autosome Chromosomal mutation: loss

or gain of autosome

Aa

Aa Aa

aaAaAA

Autosomal DisordersGene Mutations

1- Cystic Fibrosis Recessive disorder Mutated gene on chromosome

17. Characterized by excessive,

THICK secretion of the mucus in the body.

Autosomal DisordersChromosomal Mutations

Down Syndrome 1 in 1,000 live births. Trisomy-extra

Chromosome 21 Risk increases with mom’s

age Mild to severe mental

retardation

Sex-Linked Disorders Sex-linked disorder – _________________________________

__________________________________________________. Recessive gene on the X chromosome is ____________

to be expressed in males ***Y chromosome has no 2nd allele that might

counteract the gene on the X chromosome!

Sex-Linked DisordersGene Mutations

1- Color Blindness X-linked recessive disorder Gene mutation on X

chromosome 1 of 10 males

2- Hemophilia X-linked recessive disorder Gene mutation on X

chromosome. 1 of 5,000 males Interfere with normal blood

clotting

ONLY THE SEX CHROMOSOMESARE INVOLVED

Sex-Linked DisordersChromosomal Mutations

1- Klinefelter Syndrome (XXY) 1 of 1,000 males. Trisomy- extra X chromosome

Sex-linked DisordersChromosomal Mutations

2- Turner’s Syndrome (XO) 1 of 10,000 females Monosomy- one of X chromosomes

is either missing or inactive Have immature female appearance

and lack internal reproductive organs.

GENETIC DISORDERS

________________Chromosomes 1-22

_____________________Sex Chromosomes X and Y

Gene Mutations_______________ ______________________________

ChromosomalMutations

______________________________________

_______________1 gene mutated

on X chromosome

______________________________

Extra or missing Sex chromosome

EXAMPLES?

How Do We Know About Our Genes?

Human Genome Project Began in 1990; complete 2003

Goals: Determine complete sequence of the 3

billion DNA bases in human DNA Identify all human genes for further

biological study

The Unknown

________________, exact locations and functions Gene ______________ _______________ organization Chromosomal structure and organization

Ethical, Legal and Social Issues

Fears Genetic information used to harm or

discriminate Deny access to health insurance Deny employment Deny education Deny loans? Cloning?

DNA Databases

Cloning

_____________ -creating many genetically identical cellsfrom one cell.

Creation of genetically identical organisms

Why Clone Animals?

To answer questions of basic BiologyFive genetically identical cloned pigs.

For herd improvement.

To satisfy our desires (i.e. pet cloning)

For pharmaceutical production.

Is Animal Cloning Ethical?

The first cloned horse and her surrogate mother/genetic twin.

As with many important questions, the answer is beyond the scope of science.

Biotechnology

Dolly and surrogate

Mom

Genetically modified rice.Embryonic stem cells and gene therapy