Do Now:Do Now: 1. Certain acquired characteristics, such as 1. Certain acquired characteristics, such as

mechanical or mathematical skill may be mechanical or mathematical skill may be inheritedinherited.. 2. Certain 2. Certain thoughts or experiencesthoughts or experiences of a mother of a mother

mark or alter the hereditary makeup of an unborn mark or alter the hereditary makeup of an unborn child.child.

3. Color blindness is 3. Color blindness is moremore common in males than in common in males than in females.females.

4. A person may transmit characteristics to 4. A person may transmit characteristics to offspring which he/she does offspring which he/she does notnot show. show.

5. Certain inherited traits may be altered by the 5. Certain inherited traits may be altered by the stars, planets or moonstars, planets or moon early in development. early in development.

6. The total number of male births 6. The total number of male births exceedsexceeds female female births each year.births each year.

Objectives:Objectives: To distinguish between To distinguish between

heredity and inheritanceheredity and inheritance To describe Mendel’s To describe Mendel’s

experiments in heredityexperiments in heredity To compare To compare

heterozygous vs. heterozygous vs. homozygous and homozygous and dominant vs. recessive.dominant vs. recessive.

GeneticsGenetics

Chapter 4Chapter 4

Basic GeneticsBasic Genetics

Gregor Mendel

The Father

of Genetics

1866- Gregor Mendel1866- Gregor Mendel

•Austrian Monk

•Worked with Pea Plants

•Pure breeds

•Self-fertilization

•Discovered how traits were inherited in a population

HeredityHeredity – – transmission of transmission of traits traits from parents tofrom parents to their their

offspringoffspring

Inheritance passing of traits byheredity

Mendel’s experimentsMendel’s experiments used pea plantsused pea plants

PollinationPollination – transfer of pollen from – transfer of pollen from anthers to stigma in flowersanthers to stigma in flowers

1)1) self pollination self pollination occurs within the occurs within the same flowersame flower or or same plantsame plant

2) 2) cross pollinationcross pollination occurs between occurs between different plantsdifferent plants

Mendel’s Crosses with Pea PlantsMendel’s Crosses with Pea Plants

Pure tallplants

X Pure shortplantsP1

parentalgeneration

Cross Pollination

All Tall plantsF1

first filialgeneration

Self Pollination

787 tall plants, 277 short plants F2

second filialgeneration

3 to 1 ratio

Definitions

GeneticsGenetics – study of heredity – study of heredity

GeneGene – segment of DNA on a – segment of DNA on a chromosome that chromosome that codes for a codes for a

particular proteinparticular protein

genes genes occur in occur in pairspairs

AlleleAllele – alternative form of a gene – alternative form of a gene

g = yellow pods

G = green pods

t = short

T = tall

Dominant capital letter (shields recessive trait)

Recessive Lowercase

letter (usually hidden)

(Ex: Blue eyes or Brown Eyes)

Phenotype –physical characteristics of an organism

GenotypeGenotype – – genetic makeup genetic makeup of an organism ( of an organism (genesgenes))

(internal information Ex: BB, Bb, bb)

Where do Phenotypes come from?

Example of Genotype and Example of Genotype and PhenotypePhenotype

TT

genotype

Tall

phenotype

HomozygousHomozygous – – when when both both allelesalleles of a pair are the of a pair are the samesame

homozygous dominant

homozygous recessive

TT

tt

HeterozygousHeterozygous – – when when bothboth allelesalleles of a pair are of a pair are notnot the samethe same

heterozygous (tall)

Tt

In rabbits, In rabbits, blackblack fur color is fur color is dominant over browndominant over brown fur color fur color

B = black furb = brown fur

bb

BB or Bb

Think – Pair - ShareThink – Pair - Share If Fred Flintstone is heterozygous for black hair. If Fred Flintstone is heterozygous for black hair. (B=Black, b=blonde)(B=Black, b=blonde)

What is Fred’s genotype?What is Fred’s genotype?

What is Fred’s phenotype? What is Fred’s phenotype?

Tweety bird is YY. (Y= yellow feathers, y=brown Tweety bird is YY. (Y= yellow feathers, y=brown feathers)feathers) 1. What is his genotype?1. What is his genotype?

2. What is his phenotype?2. What is his phenotype?

3. Is he heterozygous or homozygous? Explain.3. Is he heterozygous or homozygous? Explain.

HomeworkHomework

Worksheet on homozygous/heterozygous Worksheet on homozygous/heterozygous and dominant and recessive.and dominant and recessive.

Due Tomorrow (or next time I see you!)Due Tomorrow (or next time I see you!)

Do Now:Do Now: Provide an example of the following terms:Provide an example of the following terms:

HeterozygousHeterozygous HomozygousHomozygous GenotypeGenotype PhenotypePhenotype Dominant Dominant RecessiveRecessive AlleleAllele GeneGene

Objective:Objective: To describe Mendel’s 3 laws To describe Mendel’s 3 laws

of inheritanceof inheritance

Complete a Monohybrid Complete a Monohybrid crosscross

**Take Out your Homework!!!**Take Out your Homework!!!

1) 1) Law of DominanceLaw of Dominance

Each trait is Each trait is controlled by 2 controlled by 2 factorsfactors, , one one factor factor ((dominant dominant ) ) may may mask the othermask the other factor factor ((recessiverecessive ) ) preventing it from having an effect.preventing it from having an effect.

P1 F1 F2

2) 2) Law of SegregationLaw of Segregation

Each allele a Each allele a person has person has separates into separates into different different gametesgametes

Ex. Ww – one W Ex. Ww – one W goes in one goes in one sperm and the sperm and the other w goes other w goes into another into another spermsperm

w WSperm

w W

3) 3) Law of Independent Law of Independent AssortmentAssortment

Gene pairs Gene pairs (homologous) (homologous) will separate will separate randomly into randomly into gametes gametes (metaphase I (metaphase I of meiosis)of meiosis)

Monohybrid CrossMonohybrid Cross R= Can roll your tongueR= Can roll your tongue r= Can’t roll your tonguer= Can’t roll your tongue

Genotype Ratio:Genotype Ratio:

Phenotype Ratio:Phenotype Ratio:

R r

R

r

Genotypic vs. Phenotypic Genotypic vs. Phenotypic RatiosRatios

Phenotype Ratio:Phenotype Ratio: Ratio of different physical traitsRatio of different physical traits Ex) Brown eyes ¼ or 25%Ex) Brown eyes ¼ or 25%

Genotype Ratio:Genotype Ratio: Ratio of the different possible allelesRatio of the different possible alleles Ex) Tt = ¼ or 25%Ex) Tt = ¼ or 25%

Test crossTest cross – an individual – an individual with with unknown genotypeunknown genotype is is crossed crossed withwith a a homozygous homozygous

recessiverecessive individual individual used to used to

determine the determine the genotype genotype of any of any individual whose individual whose phenotype is phenotype is dominantdominant

Lets Try a Test CrossLets Try a Test Cross

Spongebob squarepants doesn’t know Spongebob squarepants doesn’t know whether or not he is Homozygous whether or not he is Homozygous Dominant or Heterozygous for his Dominant or Heterozygous for his yellow color. The recessive trait is a yellow color. The recessive trait is a white sponge. Let’s say that we white sponge. Let’s say that we perform a “test cross” on spongebob perform a “test cross” on spongebob (spongebob + a white female sponge) (spongebob + a white female sponge) and all of the baby sponges are yellow. and all of the baby sponges are yellow. What would spongebob’s genotype be?What would spongebob’s genotype be?

Lets Try a Monohybrid together!1) Daffy Duck is heterozygous for black

feathers. Daisy Duck is homozygous for yellow feathers. Set up a punnett square and determine probabilities of their potential offspring. (Both genotype and phenotype ratios!)

2) B = Black b = yellow

Practice!Practice!

Get with a partner and work on the Get with a partner and work on the sample problems!sample problems!

DO NOW:DO NOW:Sleeping Beauty has freckles. Sleeping Beauty has freckles.

Her prince charming is Her prince charming is heterozygous for no freckles. heterozygous for no freckles. What are the chances of her What are the chances of her children having freckles? children having freckles? Please show your work.Please show your work.

Objectives:Objectives:

To set up and complete a To set up and complete a dihybrid cross.dihybrid cross.

What is a dihybrid Cross?What is a dihybrid Cross?

A dihybrid cross allows us to predict A dihybrid cross allows us to predict possible outcomes of offspring that possible outcomes of offspring that will have 2 traits simultaneously.will have 2 traits simultaneously. Ex: what would you get if you crossed a Ex: what would you get if you crossed a

Brown-haired brown-eyed male with a Brown-haired brown-eyed male with a blonde-haired blue-eyed female? How blonde-haired blue-eyed female? How many of the children would have brown many of the children would have brown hair and brown eyes? Brown hair and hair and brown eyes? Brown hair and blue eyes? Blonde hair and brown eyes? blue eyes? Blonde hair and brown eyes? Blonde hair and blue eyes?Blonde hair and blue eyes?

ExampleExample

Setting up Dihybrid CrossesSetting up Dihybrid Crosses

1. Determine parent genotypes1. Determine parent genotypes 2. Determine alleles to be passed 2. Determine alleles to be passed

downdown 3. Set up punnet square3. Set up punnet square 4. Determine outcome4. Determine outcome

Phenotype RatioPhenotype Ratio Genotype RatioGenotype Ratio

Dihybrid CrossesDihybrid Crosses Looking at two different traitsLooking at two different traits

Ex. Hair color and eye colorEx. Hair color and eye color

B=brown eyesB=brown eyes b=blue eyesb=blue eyes

R=Brown hairR=Brown hair r=blonde hairr=blonde hair

Mother is heterozygous for both traitsMother is heterozygous for both traits Father is heterozygous for eye color and homozygous Father is heterozygous for eye color and homozygous

dominant for hair colordominant for hair color

What could the phenotypes What could the phenotypes and genotypes be of their and genotypes be of their

children?children?

More PracticeMore Practice

Mickey Mouse is heterozygous for Mickey Mouse is heterozygous for Round ears and homozygous for Round ears and homozygous for Black eyes. Minnie Mouse also is Black eyes. Minnie Mouse also is homozygous for Floppy ears and homozygous for Floppy ears and heterozygous for Black eyes. heterozygous for Black eyes. Determine genotype and phenotype Determine genotype and phenotype ratios. (B=black, b=brown, R=round, ratios. (B=black, b=brown, R=round, r= floppy.)r= floppy.)

Practice!Practice!

It’s Harry Potter time!! Get with a It’s Harry Potter time!! Get with a partner and work on the sample partner and work on the sample problems involving some of my problems involving some of my favorite fictional characters!favorite fictional characters!

DO NOWDO NOW

Take out your Harry Potter Take out your Harry Potter Homework!Homework!

What is the phenotypic ratio for a What is the phenotypic ratio for a dihybrid cross where each parent is dihybrid cross where each parent is heterozygous for both traits?heterozygous for both traits?

Objectives:Objectives:

To define gene To define gene linkage and linkage and polypoidy.polypoidy.

To understand To understand pedigrees and figure pedigrees and figure out how to use one.out how to use one.

10.3 Gene Linkage and 10.3 Gene Linkage and PolyploidyPolyploidy

Several genes on a chromosomeSeveral genes on a chromosome Gene Linkage:Gene Linkage:

When two genes are close to each other When two genes are close to each other on the same chromosome on the same chromosome

Gene LinkageGene Linkage

Linked genes on a chromosome Linked genes on a chromosome results in an results in an exceptionexception to Mendel’s to Mendel’s law of independent assortment law of independent assortment

Linked genes usually do not Linked genes usually do not segregate independentlysegregate independently

Drosophila (Fruit Flies)Drosophila (Fruit Flies)

First organism with linked genesFirst organism with linked genes Linked genes Linked genes typicallytypically travel travel

together during crossing overtogether during crossing over

Chromosome MapChromosome Map

Crossing over occurs more frequently Crossing over occurs more frequently between genes that are far apartbetween genes that are far apart

Map of genes on a chromosomes and Map of genes on a chromosomes and frequency of crossing overfrequency of crossing over

PolyploidyPolyploidy Occurrence of one or more extra sets Occurrence of one or more extra sets

of all chromosomes in an organism.of all chromosomes in an organism. Ex. A triploid organism (3Ex. A triploid organism (3n) -n) - means means

that it has three complete sets of that it has three complete sets of chromosomes.chromosomes.

True or False – Correct false True or False – Correct false statementsstatements

_______   1_______   1.. Crossing over occurs more frequently Crossing over occurs more frequently between genes that are close together on a between genes that are close together on a chromosome.chromosome.

_______   2_______   2.. Gene linkage was first studied by Gene linkage was first studied by using garden peas.using garden peas.

_______   3_______   3.. Scientists call a drawing like the one Scientists call a drawing like the one shown below a chromosome map.shown below a chromosome map.

_______   4_______   4.. Chromosome map percentages Chromosome map percentages represent actual chromosome distances.represent actual chromosome distances.

MatchingMatching

PedigreePedigree

Shows history of a trait in a familyShows history of a trait in a family Allows researchers to analyze traits Allows researchers to analyze traits

within a familywithin a family

Symbols for PedigreeSymbols for Pedigree

Lets try to figure out their Lets try to figure out their genotypes!genotypes!

Dominant or RecessiveDominant or Recessive Pedigrees can depict both dominant Pedigrees can depict both dominant

and recessive traits… and recessive traits…

HomeworkHomework

Pedigree worksheet! Due next class! Pedigree worksheet! Due next class! – worth 5 points!!– worth 5 points!!

Do NowDo Now

Take out pedigree homework!Take out pedigree homework! Fill in the genotypes for the following Fill in the genotypes for the following

pedigreepedigree B=brown eyesB=brown eyes b = blue eyesb = blue eyes

ObjectivesObjectives

To understand incomplete To understand incomplete dominance and be able to do dominance and be able to do incomplete dominance monohybrid incomplete dominance monohybrid crosses.crosses.

To explain codominance, multiple To explain codominance, multiple alleles, sex-linked traits, and alleles, sex-linked traits, and polygenic inheritence.polygenic inheritence.

Test CrossTest Cross

When the genotype of an individual When the genotype of an individual is unknown, cross the individual with is unknown, cross the individual with a homozygous recessive a homozygous recessive

The outcome of the cross determines The outcome of the cross determines the genotype of the unknownthe genotype of the unknown

11.2 11.2 Incomplete Incomplete Dominance:Dominance: Heterozygous Heterozygous phenotypephenotype is an is an

intermediate phenotype between the intermediate phenotype between the two homozygous phenotypes.two homozygous phenotypes.

Two alleles are Two alleles are blendedblended Ex) Four O’clock FlowersEx) Four O’clock Flowers RedRed + + WhiteWhite = = PinkPink

Incomplete Incomplete DominanceDominance

CodominanceCodominance

Neither trait is dominant instead, Neither trait is dominant instead, both traits are shown (No Blending)both traits are shown (No Blending)

Ex) Roan CowsEx) Roan Cows RedRed + + WhiteWhite = = RREEDD AANNDD WWHHIITTEE

Sickle Cell DiseaseSickle Cell Disease Affects red blood cells and ability to Affects red blood cells and ability to

transport oxygen.transport oxygen.

Homozygous recessive alleles=Homozygous recessive alleles=

Heterozygous=Heterozygous=

Homozygous dominant alleles=Homozygous dominant alleles=

Sickle Cell and MalariaSickle Cell and Malaria

People who are People who are heterozygous for heterozygous for sickle cell, have a sickle cell, have a higher resistance to higher resistance to malaria.malaria.

Multiple allelesMultiple alleles – – 3 or more3 or more alleles alleles that control a trait that control a trait

ExampleExample – blood type (I – blood type (IAA,I,IBB,i,ioo))

GENOTYPESGENOTYPES IIAAIIAA IIAAiioo

RESULTING PHENOTYPESRESULTING PHENOTYPES Type AType A Type AType A

IIBBIIBB IIBBiioo

Type BType B Type BType B

IIAAIIBB Type ABType AB

iiooiioo Type OType O

Universal Donor?Universal Donor?

Sample ProblemSample Problem

Determine the possible offspring of Determine the possible offspring of the following crossesthe following crosses

1. AB and O1. AB and O 2. AA and BO2. AA and BO 3. AB and AB3. AB and AB

Coat Color of RabbitsCoat Color of Rabbits Rabbits have a hierarchy of coat colorRabbits have a hierarchy of coat color 4 alleles (4 alleles (CC,, c cchch,, c chh,, and and cc)) Dominant CDominant C > > ccchch>> c ch h >> c c Recessive Recessive

C Full colorC Full color ccchch Chinchilla Chinchilla cchh Himalayan Himalayan c albino c albino

Coat Color of Rabbits

Full Color Himalayan

Albino

Chinchilla

Let’s try a sample problemLet’s try a sample problem

cc x Cccc x Ccchch

Genotype and phenotype ratiosGenotype and phenotype ratios

What do you see?What do you see?

What do you see?What do you see?

Sex Linked TraitsSex Linked Traits

Traits located on the sex Traits located on the sex chromosomes (X or Y)chromosomes (X or Y)

X linked:X linked: gene is located on the X gene is located on the X chromosomeschromosomes

Y linked:Y linked: gene is located on the Y gene is located on the Y chromosome chromosome

What are the chances of having a What are the chances of having a girl?girl?

How would you go about solving it?How would you go about solving it?

Sex-Linked TraitsSex-Linked Traits

A man who is color blind marries a A man who is color blind marries a woman that is heterozygous for color woman that is heterozygous for color blindness. What is the chance of blindness. What is the chance of having a color blind boy?having a color blind boy?

Polygenic Traits

Polygenic traits arise from the interaction of multiple pairs of genes.

Objectives:Objectives:

To define test crossTo define test cross

To define incomplete To define incomplete dominancedominance

To define codominanceTo define codominance

CodominanceCodominance – condition in – condition in which which both allelesboth alleles of a gene are of a gene are

expressedexpressed

exampleexample – roan coat in horses – roan coat in horses

white hair (Hwhite hair (HWW)) is codominant with is codominant with redred hair (hair (HHRR))

horses with genotype (horses with genotype (HHRRHHWW) ) have have coats with a mixture of coats with a mixture of redred andand whitewhite hairshairs (roan) (roan)

Roan CoatRoan Coat

Objectives:Objectives:

To predict the results of To predict the results of dihybrid crosses by using dihybrid crosses by using a Punnett squarea Punnett square

dihybrid crossdihybrid cross – cross – cross between individuals that involves between individuals that involves two pair of contrasting traitstwo pair of contrasting traits