Some individuals are able to bend theirthumb back at the distal joint at 50° or more

Human Heredity

PTC Taster

• The ability to detect a specific taste from the chemical phenylthiocarbamide (PTC) has been labeled as the trait PTC Tasting or Taster..

• The gene for this trait has been mapped to the long arm of chromosome 7.

Individual Phenotypes

Thumb Tongue Roll Little Finger Earlobes PTC

Bent Straight Roller Non-roller Bent Straight Free Attached Taster non

Thumb Tongue Roll Little Finger Earlobes PTC

Bent Straight

Roller Non-roller

Bent Straight

Free

Attached

Taster

non

# of student

s

% of student

s

Class Phenotypes

How do the class data compare to the actual answers?

BentPinky Straight Dominant

Roller DominantNon-roller

Thumb Bent DominantStraight

Free DominantAttached

Taster Dominantnon

Heredity

DNA- deoxyribonucleic acid, stores genetic information

NOVA Online | Cracking the Code of Life | 9 min, 6 min

Gene- a segment of DNA that codes for a trait

Heredity

Chromosome-

rod-shaped body, found in the nucleus, made of the DNA molecule

Chromatin- loosely stored, relaxed DNA 25 to 30 THOUSAND genes at “rest”

Mendel’s “factors”Are Chromosomes!video clip

Karyotyping

• In your lab tutorial, you looked at three patients who needed diagnosis.

For all three patients, what was the trouble?• Specifically A? B? C?

Last name lineup, check in Lab Notes

Genetics- field of biology, study of heredity

Heredity- how characteristics are passed from parent to offspring

These black Labrador puppies are purebred—their parents and grandparents were black Labs with very similar genetic makeups.

• The parents of these puppies were a mixture of different breeds – Their behavior

and appearance is more varied as a result of their diverse genetic inheritance

• WHO WAS HE?– Father of Genetics– Monk who lived in mid-1800s– worked with pea plants and researched heredity

Gregor Mendel

Figure 9.2A, B

FLOWER COLOR

FLOWER POSITION

SEED COLOR

SEED SHAPE

POD SHAPE

POD COLOR

STEM LENGTH

Purple White

Axial Terminal

Yellow Green

Round Wrinkled

Inflated Constricted

Green Yellow

Tall Dwarf

Mendel observed 7 different plants characteristics of peas. These characteristics were called traits…

• Three Key CHOICES-– Control over the breedings– Use of purebred plants for Parent Gen.– Written observations of “either-or” traits

G. Mendel

Figure 9.2A, B

FLOWER COLOR

FLOWER POSITION

SEED COLOR

SEED SHAPE

POD SHAPE

POD COLOR

STEM LENGTH

Purple White

Axial Terminal

Yellow Green

Round Wrinkled

Inflated Constricted

Green Yellow

Tall Dwarf

Mendel Cont.

• Peas are great to study because – Only two possible

characteristics per trait– they easily cross-pollinate– and have many offspring!

• Trait- a category that has two or more contrasting characteristics– Ex- seed color

What are each of the traits shown in the pairs below?

FlowerColor

FlowerPosition

SeedColorSeedShapePodShape

PodColor

StemLength

Mendel’s Experiments

• In Mendel’s plant experiments, he used special names to describe each generation of pea plants

• P1 generation- parent generation

• F1 generation- offspring of parent generation

• F2 generation- offspring of F1 generation

Mendel and his Experiments- Video

RESULTS 1 Removed stamensfrom purple flower

White

Stamens

Carpel

PurplePARENTS(P)

OFF-SPRING

(F1)

2 Transferred pollen from stamens of white flower to carpel of purple flower

3 Pollinated carpel matured into pod

4 Planted seeds from pod

Dominant- (capital) a trait that covers another

Recessive- (lower-case letter) trait that is hidden by a dominant gene

Survey 5 people (including yourself)Based on your data,

is a Widow’s peak dominant or recessive?

What is your genotype?(Hint: assign letters for Widow’s peak and no Widow’s peak)

• different forms of a gene that code for a trait• reside at the same place on homologous chromosomes

Example- Bb

Alleles

GENE

Figure 9.4

P a B

DOMINANTallele

RECESSIVEallele

P a b

GENOTYPE: PP aa Bb

HOMOZYGOUSfor thedominant allele

HOMOZYGOUSfor therecessive allele

HETEROZYGOUS

P= purplep = whiteA = axiala= terminalB= budsb= no buds

Mendel’s Laws, Genotype vs. Phenotype- Video

Genotype- genetic makeup of an organism (alleles) Example- PP

Phenotype – physical appearance of an organism

Example- purple colored petals

Figure 9.4

P a B

RECESSIVEallele

P a b

GENOTYPE: PP aa Bb

HOMOZYGOUSfor thedominant allele

HOMOZYGOUSfor therecessive allele

HETEROZYGOUS

gene

P= purple

p = white

A = axial

a= terminal

B= buds

b= no buds

For those with a widow’s Why is your genotype W?

Homozygous= Purebred = having two copies ofthe same allele; BB or bb

Heterozygous= Hybrid = two different alleles; Bb

Figure 9.4

P a B

RECESSIVEallele

P a b

GENOTYPE: PP aa Bb

HOMOZYGOUSfor thedominant allele

HOMOZYGOUSfor therecessive allele

HETEROZYGOUS

gene

P= purple

p = white

A = axial

a= terminal

B= buds

b= no buds

Review Question

What is the difference between genes and alleles?

Example: Blood type is the gene, what would the alleles be? Pg.205

Should this Dog be named Spot?

L t H A

l T H a

Hair length

Short L Long l

Hair texture

Wiry T Silky t

Hair curliness

Curly H Straight h

Coat pattern

Spot A Solid a

What is his GENOtype?

What is his PHENOtype?

What trait is he Homozygous for?

Mendel: Law of Segregation

From his pea experiments, Mendel believed:

• Each individual inherits 2 copies of every gene.

• During the formation of gametes, the 2 copies of a gene separate “segregate” (1 copy in every gamete).

Parent 1 Parent 2

What happens when the F1s cross?

Law of Segregation Cont.

MONOHYBRID CROSSES

• Monohybrid Cross- involves one pair of contrasting traits– Example- Cross a male

and female, determine the gender of offspring

• Punnett Square- Who? R.C.Punnett, geneticist What? tool used to predict the

outcomes of crosses

Punnett squares Who? P.183

• The Punnett square: grid system for predicting all possible genotypes from a mating (cross).– axis- each parent

possible gametes

– inside grid possible

offspring genotypes

• Punnett square yields ratio of potential genotypes and phenotypes.

Law of Independent Assortment-

Factors for different

characteristics are

distributed to gametes

independently

A dihybrid cross involves two traits.

• Mendel’s dihybrid crosses led to his second law,the law of independent assortment.

• The law of independent assortment states that allele pairs separate independently of each other during meiosis.

• Mendel’s dihybrid crosses with heterozygous plants yielded a 9:3:3:1 phenotypic ratio.

Dragon Lab

Mom Dad Alleles in

Egg

Alleles in

Sperm

Baby

Phenotype

Genetics and Probability• Probability- the likelihood that a specific

outcome will occur– Expressed as: a fraction, decimal ratio, or %– In a basic Punnett Square, you have four 4

boxes so your ratios could be 1:4 (25%) , 2:4(50%) , 3:4(75%) , 4:4 (100%)

Mendel’s works : 126 red: 122 white 126/248 = 50.8 % P(red)

Your Notes look like this…

EACHWILLBE A SEPARATEEXAMPLE

PunnettSquares

Example 1: Homozygous x Homozygous

Homozygous for purple PP = purple Homozygous for white pp = white

Genotypic Ratio: Phenotypic Ratio:

Example 2: Homozygous x Heterozygous

Homozygous for black coat BB Heterozygous for black coat Bb

Genotypic Ratio: Phenotypic Ratio:

Example 3: Heterozygous x Heterozygous

Heterozygous for black coat Bb Heterozygous for black coat Bb

Genotypic Ratio: Phenotypic Ratio:

Example 4: Testcross- individual of unknown genotype is crossed

with a homozygous recessive individual

Genotypic Ratio:

Phenotypic Ratio:Homozygous

Recessive

UNKNOWN!Is he BB or Bb?

TEST CROSS

Results tell whether tested individual is PUREBRED or HYBRID dominant.

---Test Cross Ex. Would give 100% Dominant offspring if the individual was PURE for the dominant trait.

---ANY recessive phenotype offspring mean the tested parent must have been HETEROZYGOUS

Test Cross example 2

P1 - ?Unknown Dominant? X Homozygous RecessiveROUND wrinkle

? RR -or- Rr ? We know is [[ rr ]]

F1 - If offspring are ALL round, then unknown parent was ______________

If some offspring phenotype shows wrinkles,then the unknown parent was ___________

Smiley : Genotype vs. Phenotype

• Finished product - Word doc• DUE: Print/Color by Hand = HALL

– POST TO WIKI - Go to YOUR HOUR’s PAGE, Upload Tool

• Title at top : Genotype vs. Phenotype Smiley» Draw Smiley by “INSERT” > Pictures > AutoShapes

– At Bottom: Name your Smiley» Give names: yours & partners» List Hour #

CROSS OFFSPRING ACTUAL RATIO

APPROXIMATE RATIO

Long stem x long stem

787 long 277 short

Green pods x green pods

428 green 152 yellow

CROSS OFFSPRING ACTUAL RATIO

APPROXIMATE RATIO

Peas with axial flowers x peas with terminal flowers

652 axial flowers

206 terminal flowers

Fruit flies, normal wings x curly wings

103 normal wings

92 curly

Oval radishes x oval radishes

25 long radishes

52 oval radishes

28 round radishes

Tongue rollers x tongue rollers

755 tongue rollers

245 non-rollers

Beyond Mendel

More Complex Inheritance& Sex-Linked Traits

Incomplete Dominance

• An inheritance relationship in which a “mix” or blend of the two alleles is produced

Incomplete Dominance

• A cross between round radishes and long radishes produces oval radishes. (incomplete dominance).

A cross between round radishes and long radishes produces oval radishes. (incomplete dominance). If oval radishes were selling for the most money, what would you cross for highest profit?

a. round x round b. round x longc. oval x oval d. long x oval

Co-Dominance

-Both alleles are visible in the phenotype

-examples- Lubber grasshopper or a roan horse--- or my sable corgi !

The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes.

A. What is the expected genotypic ratio of the F1 generation?

B. What is the expected phenotypic ratio of the F1 generation?

C. What percent is expected to be white?

D. How do incomplete dominance and co-dominance differ?

E. Using your text, explain how blood typing illustrates both complete dominance and co-dominance?

1 RW: 0

1 roan: 0

0%

Example 1: Homozygous x Homozygous

Round (RR) Yellow (YY) seeds crossed with Wrinkled (rr) green (yy) seeds

Genotypic Ratio: Phenotypic Ratio:

Dihybrid Cross

• Mono = One… so Monohybrid cross we were only focusing on ONE trait.

• Di = Bi = Two

Example 1 XSo DiHybrid

cross considers two traits at the same time.

Dihybrid Cross pg. 171Round= R wrinkle= r // Yellow = Y green=y

RY Ry rY ry

RY

Ry

rY

ry

Example 2: Heterozygous x Heterozygous

Round (Rr) Yellow (Yy) seeds crossed with Round (Rr) Yellow (Yy) seeds

Genotypic Ratio: Phenotypic Ratio:

Dihybrid cross GgNn x GgNn

GN Gn gN gn

GN GGNN GGNn GgNN GgNn

Gn GGNn GGnn GgNn Ggnn

gN GgNN GgNn ggNN ggNn

gn GgNn Ggnn ggNn ggnn

Phenotypic ratio: 9 green, smooth:

3 green, wrinkled

3 yellow smooth

1 yellow wrinkled

REVIEW Genetic Crosses

homozygous = having two copies of the same allele

heterozygous = having two different alleles

Genotype- genetic makeup of an organism (alleles)

Phenotype – physical appearance of an organism

1. Guinea pigs1. Black - 2. ____ x ____

white –

3. Punnett square –

4. Genotypic ratio:

5. Phenotypic ratio:

2. Curly vs Straight

C= curly Cc x cc

c = straight

genotypic ratio: 1 Cc : 1 cc

phenotypic ratio : 1 curly: 1 straight

Cc Cc

cc cc

C

c

c c

3. In peas. . .1. Tall - 2. ____ x ____

dwarf –

3. Punnett square –

4. Genotypic ratio:

5. Phenotypic ratio:

The following traits are dominant: +brown eyes+curly hair+attached earlobes+curling tongue.

Which one is Wanda’s mom?

Dad = Brown B?

curly C?

unattached aa

roller R?

Wanda= Brown B?

curly C?

attached A?

roller R?

The following traits are dominant: brown eyescurly hairattached earlobesrolling tongue

MOM 1

Wanda got a from dad, had to get the A from mom, Mom one has a A to give

Probability of 2 coins

Coin #1Coin #2

H H

H T

T H

T T

HH HT

HT TT

1/4

1/4

¼ + ¼ = ½ OR

H

T

H T

Test cross- an unknown genotype is crossed with a homozygous recessive individual

TESTCROSS:

B_GENOTYPES bb

BB Bbor

Two possibilities for the black dog:

GAMETES

OFFSPRING All black 1 black : 1 chocolate

B

b

B

b

b

Bb Bb bb

?

6. In mice, black coat is dominant over white. Outline possible crosses to determine whether a black mouse is homozygous or heterozygous. ___ = black

___ = white

_______ x _bb___(black) (testcross)BB or Bb

Pg 10 #7

If two black mice are mated several times. . .

Results: 23 black : 8 white

What do you know about the parents?

Lubber Grasshopper (co-dominant)

The lubber grasshopper is a very large grasshopper, and is black with red and yellow stripes.

RR = red stripes

YY = yellow stripes

RY = red and yellow stripes

4. Cross two lubbers, both with red and yellow stripes. List phenotypic ratio. 1 red: 2 red and yellow: 1 yellow

In mice. . .Running mice =

Waltzing mice =

Black =

brown =

1. hom. run/hom.black x

hetero run/hetero blk

________ x ________

Phenotypic ratio:

RB

RB

Rb

rB

rb

RRBB

RRBb

RrBB

RrBb

2. ___________ x _____________hetero run hetero run

hetero black pure brown

Answer: 3 run black:

1 waltz black:

3 run brown:

1 waltz brown

Answers to dihybrid practice problems

1. Phenotypic ratio: 4 run black :0

2. Phenotypic ratio: 3 run black

1 waltz black:

3 run brown:

1 waltz brown

3. Phenotypic ratio: 1 run black: 1 run brown

4. Phenotypic ratio: 3 run black: 1 waltz black

Genetic corn

What phenotypes do you see on your cob?

Brown & Smooth (A),

Brown & wrinkled (B),

Yellow & Smooth (C)

Yellow & Wrinkled (D).

Which is dominant?          

Brown = Smooth =Yellow = wrinkled =

If the P1 generation was heterozygous for both traits, hypothesize what will be your phenotypic ratio?

Phenotypes 1 2 3 4

Description

Number present llll ll ll l

Class Results

Ratios

brown brown yellow yellow

smooth wrinkled smooth wrinkled

Class Results

brown smooth

Brown

wrinkled

Yellow smooth

Yellow wrinkled

Corn Punnett Square

BS Bs bS bs

BS

Bs

bS

bs

Phenotypic ratio: 9 brown, smooth:

3 brown, wrinkled

3 yellow, smooth

1 yellow, wrinkled

Dihybrid Lab

• In corn, brown kernels are dominant over yellow kernels.

• Smooth texture is dominant over wrinkled.

• Cross a hybrid brown, wrinkled corn with a yellow, heterozygous smooth corn.

• What percent will be brown and smooth?

Pg 22 # 5 Aliens from Mars

_______________ x _______________ hetero for both hetero for both

Aliens from Mars

1. E= 2 eyes

e = 1 eye

T = triangle

t = pentagon2. EeTt x EeTt

A. What is the expected genotypic ratio of the F1 generation?

B. What is the expected phenotypic ratio of the F1 generation?

C. What percent is expected to be white?

D. If for Valentine’s Day a florist wanted all pink flowers, what would be the phenotypes for the parents?

1 RW: 0

Red x white

1 pink: 0

0%

Genetic Word Problems

1. Red is INCOMPLETELY dominant over white

Red = ________ x ________White = pink white

Pink =

RR

WW

RW

RW WW

R W

W RW WW

W RW WW

Genetic Word Problems

2.

Red = ________ x ________White = roan roan

roan =

1. Genotype ratio: 1RW : 1WWPhenotype ratio: 1 pink: 1 white

2. Genotypic ratio 1 RR: 2 RW: 1WWPhenotypic ratio 1 red : 2 roan: 1 white% dominant 50%

3. Genotypic ratio 1 AA: 1AaPhenotypic ratio 1 dominant: 0% dominant 100%

4. Genotypic ratio 1 YyWw: 1 YywwPhenotypic ratio 1 yellow web: 1 yellow hoof% dominant yes 50%