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Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics • What is genetics? – __________________ = the passing of traits from parents to offspring – Why is your combination of genes unique?

Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

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Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics. What is genetics? __________________ = the passing of traits from parents to offspring Why is your combination of genes unique?. Gregor Mendel – the Father of Genetics 1822-1884. Mendel ’ s Experiments. - PowerPoint PPT Presentation

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Page 1: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Unit 6: Genetics & HeredityCh 12 and 13: Heredity & Human

Genetics

• What is genetics?– __________________ = the passing of traits

from parents to offspring

– Why is your combination of genes unique?

Page 2: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Gregor Mendel – the Father of Genetics

1822-1884

Page 3: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Experiments• Studied garden peas – _____ different traits

with clearly different forms– Tried to determine how these traits were transmitted

from parent to offspring

Page 4: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Male & female parts in same flower–Normally

• Self pollinate–Produce pure

offspring» ______ parents

produce______ offspring

» ______ parents produce _________ offspring

Mendel’s Experiments

Page 5: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Experiments• Cross pollination of pure

purple parent & pure white parent (parent generation)• Purple offspring (________

____________ generation)• Hybrids (genes for both

purple & white in all offspring)

Page 6: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Offspring allowed to self pollinate• New offspring (F2, second filial, generation) weren’t

all purple– _______– _______

Mendel’s Experiments

Parent

First filial

Second Filial

Crossed 2 F1 plants to get F2

Page 7: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Principle of Dominance• Mendel noted that for each trait one form

dominates the other– In other words, the __________ trait prevents

the expression of the _______________ trait.• Ex. In peas, purple x white gives all purple

offspring– ____________________– ____________________

Page 8: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Punnett Squares• Helps to predict the results of crosses

– all possible resulting offspring• & the probability of each offspring’s genes

• Ea. parent can contribute 1 of 2 genes for a trait (______)- found on homologous chromosomes– Represent with letters

• ________________ = dominant gene• ________________ = recessive gene• ________________ – alleles same

– ex. AA or aa

• ________________ – alleles different– ex. Aa

Page 9: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics
Page 10: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Genotype vs. Phenotype• ____________________ = actual

genetic make-up of individual– represented by letters

• __________ = outward (physical) expression of the genotype– (due to) the protein that is produced

• Ex. Let P = purple & p = white– Genotypes PP & Pp both have the

same phenotype (purple)• PP = ________________ dominant

• Pp = ________________________

– Genotype pp has (white) phenotype:• pp = ________________ recessive

Page 11: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics
Page 12: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Principle of Segregation• During gamete formation, the

pair of genes responsible for each trait separates so that each gamete receives only 1 gene for each trait.– happens during meiosis I when

homologous chromosomes line up (randomly) @ equator (metaphase 1) & separate (anaphase 1)

Draw diagrams

Page 13: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Principle of Segregation

Page 14: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Principle of Segregation• tested segregation using

heterozygous purple flower & homozygous white flower– Predicted _______ purple

& ____ white offspring b/c:• P gene would combine w/

p gene _______ the time– producing __________

_____________ flowers

• p gene would combine w/ p gene _______ the time

– producing ___________ _____________ flowers

Draw Punnett Square

Page 15: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Mendel’s Principle of Independent Assortment• Genes for different traits segregate independently

during gamete formation when they are located on different chromosomes…– What if they are on the same chromosome?

Genes on samechromosome

Genes on samechromosome

meiosis

Page 16: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics
Page 17: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Probability• The chance an event

will occur

• What is the chance of getting heads? Tails?– If you flip two coins, of

getting 2 heads? 2 tails?

– What is the chance of a couple having a boy? A girl? Of having four boys? Five girls?

Draw Punnett Square

Page 18: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Ratios• _________________________= probable ratio

of genotypes in offspring of a cross– Ex. If cross PP & pp

• 1PP : 2Pp : 1 pp

• _________________________= probable ratio of phenotypes resulting from the genotypic ratio

• Ex. If cross PP & pp• 3 purple : 1 white

• ________________________________ = ratio expected based on probability (Punnett Square)

• ___________________ = what actually occurs– Why would these be different?

Page 19: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Phenotypegenotype

Phenotypegenotype

Pp

Pp

Pp

Pp

P p

p P

Page 20: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Monohybrid Cross• a cross where __________________________

________________________ (gene) is studied– ex. only height, flower color, eye color, etc...

T t

Draw Punnett Square

Page 21: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Dihybrid Cross• involves study of inheritance patterns for

organisms differing in _______ (ea. w/ 2 forms).– Mendel determine if different traits of pea plants,

such as flower color & seed shape, were inherited independently.

Dihybrid Cross Animation

Page 22: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Dihybrid Cross

2 traits with 2 forms

Page 23: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Test Cross• Used to determine

__________________

of dominant phenotype– Cross ______________

phenotype w/ ________ phenotype

• If any offspring show recessive trait, unknown parent ____________

• If all show dominant trait, then parent ________ ____________________

Show as P_

Draw Punnett Squares

Page 24: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Dominant/Recessive is Not Always the Mode of Inheritance

• Traits are not always as clearly defined as the 7 pea plant traits Mendel studied– Incomplete dominance– Codominance– Multiple alleles– Sex-linked inheritance– Polygenic inheritance

• Continuous variation

Page 25: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Incomplete Dominance• No allele is ________

__________________– results in _ phenotypes

– ________________, ___________ (mixed), __________________. • Genotypic & phenotypic

ratios same– ___________________ – ___________________

– Ex. Pink four o’clock flowers Draw Punnett Square

Page 26: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Codominance• heterozygote

displays the protein products of both alleles __________

– Ex. Roan cow has a mixture of both red & white hairs.

Page 27: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Multiple Alleles• More than _______________ different forms of

an allele exist, but individual still has just 2.

• Ex. alleles that code for human blood types– A = _____– B = _____– O = _____– exhibit both codominance & multiple alleles

• (______= ______ ) > ______•How many possible genotypes are there?

•How many phenotypes?

•Can you spot the blood type that is a product of codominance?

Copy Chart

Page 28: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

antigen

antigen

antigens

No antigens

Page 29: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Agouti rabbits– 4 alleles: C, cch, ch, c

– w/ dominance relationship to one another: _________________________________

• agouti rabbit (wild type)– Phenotype: brown, Genotype: CC, Ccch, Cch, or Cc

• “Chinchilla” (mutant)– Phenotype: silvery gray, Genotype: cchcch, cchch, or cchc

• “Himalayan” (mutant):– Phenotype: white w/ black points, Genotype: cchcch chch or chc

• “Albino” (mutant)– Phenotype: white, Genotype: cchcch cc

Multiple Alleles

Page 30: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Sex Determination• In humans chromosomes:

– Pairs 1 – 22 = ____________________– 23rd pair determine gender = __________________

• __________ = female• __________= male

What is the probability of having a son? A daughter?

Draw Punnett Square

Page 31: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Sex-linked Inheritance• X & Y chromosomes not fully homologous

– X is bigger & carries more genes

• Males will have _____________________ for traits carried only on X– called _______________________________

• Ex.: – In Drosophila (fruit flies) eye color– In humans _______________________________

___________________________________________

– X-linked traits more common in males• Why???

Page 32: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Predictions made using Punnett square– Include sex of each parent– Consider the sex chromosomes & genes they

carry together as a unit…• ex. XG (= dominant gene), Xg (= recessive gene),

Y (= no gene)

Sex-linked Inheritance

XG female Xg

Complete Punnett Square

Page 33: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Ex. In Drosophila (fruit flies) eye color– What are the sex, genotype, & phenotype of each

F2 offspring?• Are there any female carriers for the white eye gene?

Sex-linked Inheritance

Heterozygous red-eyed

carrier for white eye allele

red-eyed

P generation genotypes were XRXR & XwY

Page 34: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Sex-linked Inheritance

– If mother is carrier & father has hemophilia:

• genotypic ratio?• phenotypic ratio?

– If mother is carrier & father is normal:

• Make a Punnett square– genotypic ratio?– phenotypic ratio?

•Hemophilia is X-linked recessive

Draw Punnett Square

Page 35: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• pedigree chart showing inheritance of hemophilia

– Does hemophilia affect one gender more often?

• Why?

Sex-linked Inheritance

Page 36: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Colorblindness is X-linked recessive– In this Punnett square, what are

the genotypes & phenotypes of the parents?

Sex-linked Inheritance

Ishiharatest forred-greencolorblindness

Page 37: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Polygenic Inheritance• ______________

______________ affect a single trait– shows range of

phenotypes from one extreme to another (_______ ______________)• Ex. in humans:

hair color, height, skin color

Page 38: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Expression of Genes• Genes can _______________________ to

control various other patterns of inheritance– Most characteristics that make up individual’s

phenotype not inherited in Mendelian patterns• Ex. Modifier genes affect eye color

– influence amount, intensity, & distribution of melanin (color pigment) in eye cells

Page 39: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• ____________________________ in which organism develops is another factor that affects expression– Probably due to how enzymes (proteins) operate at different

temperature• Higher temps may “deactivate” enzyme & prevent a reaction form

occurring (therefore, changing phenotype)

• Examples:– temp & size of fruit fly wings: Warmer temps = larger wings

& colder temps = smaller wings– __________: Low altitudes = taller & high altitudes = shorter– ____: Poor soil or drought may produce shorter (or no) ears– _______ seedlings: Green (dominant) & albino (recessive)…

• however green color is also affected by environment– No sunlight green color cannot be expressed due to lack of chlorophyll production– Put in light green will appear b/c chlorophyll being produced

Expression of Genes

Page 40: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Human Genetic Disorders

Page 41: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Pedigree Charts• A ____________________________

______________________________ of family over several generations–Scientist or a genetic counselor would

find out about your family history & make this chart to analyze.• used to find out probability of a child having

a disorder in a particular family–To begin to interpret a pedigree, determine if

the disease or condition is autosomal or X-linked and dominant or recessive.

Page 42: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Pedigree Chart

Square = ___________________________

Circle = ____________________________

Shaded = __________________________

Marriage = _________________________

Offspring = _________________________

Page 43: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Due to DNA mutation (usually recessive) or chromosome abnormalities (# or structure)– Causes production of abnormal proteins

• Examples:– ______________________________ (***most genetic disorders)

» Cystic Fibrosis

» Sickle-cell Anemia

» Tay-Sachs Disease

– _________________________________________________________

» Huntington’s Disease

– _____________________________________________________

» Hemophilia

» Color Blindness

– _________________________________________________________

» Down Syndrome (trisomy 21)

» Klinefelter’s Syndrome

Human Genetic Disorders

Page 44: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Autosomal Recessive• Must be _____________ b/c allele

needed to produce trait is _______– Cystic Fibrosis

– Sickle-cell Anemia (A normal, S sickle-cell trait)

– Tay-Sachs Disease A female S

Complete Punnett Squares

Page 45: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Autosomal Dominant• Can be homozygous or heterozygous b/c allele

needed to produce trait is dominant– Huntington’s Disease

Draw Punnett Square

Page 46: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Sex-linked Disorders•Hemophilia•Color blindness

Complete Punnett Squares

Page 47: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Chromosomal Abnormalities• Affects ________

____________ of chromosomes– #:

• Down Syndrome (____________ … _______ copies of chromosome # __)

– Cause _______ ______________ (failure of paired chromosomes to ______________ during meiosis 1 or meiosis 2)

Page 48: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• Klinefelter’s Syndrome– Sex chromosome disorder

» Males have ________ __________________ _______ chromosome *XXY (or 47, XXY b/c 47

total chromosomes)

» Cause __________ __________________ (failure of paired chromosomes to __________________ during meiosis 1 or meiosis 2)

Detecting Abnormalities

Page 49: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Chromosomal Abnormalities• Affects # or

structure of chromosomes– Structure:

• Added, deleted, inverted, or translocated pieces

Page 50: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Detecting Abnormalities• ______________

– “picture of human chromosomes”• From blood

sample– Can detect _____

______________ ______________ ______________ ______________ (additions, deletions, inversions, translocations)

Page 51: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

• _________________– sample of fluid

surrounding fetus (karyotype then made)

• Can detect _________ __________________

– 14th + week of preg.

• _________________ _____ sample of cells from chorion (part of structure by which fetus linked to mother)

– 9th + week of preg.

Detecting Abnormalities

Page 52: Unit 6: Genetics & Heredity Ch 12 and 13: Heredity & Human Genetics

Review & Animations• Vocab interactive

– http://nortonbooks.com/college/biology/animations/ch10a02.htm

• Crosses– http://www.sonefe.org/online-biyoloji-dersleri/grade-12/monohybrid-

cross/

• Drag & drop genetics– http://www.zerobio.com/drag_gr11/mono.htm

• Various– http://www.abpischools.org.uk/page/modules/genome/dna4.cfm?

coSiteNavigation_allTopic=1

• Pedigrees– http://www.learnerstv.com/animation/animation.php?ani=13&cat=biology

• Genetic disorders– http://www.humanillnesses.com/original/Gas-Hep/Genetic-Diseases.html