Tuesday April 4, 2017 Agenda - PowerPoint Presentation

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TuesdayApril 4, 2017

Agenda(10) Catalyst(25) GN and Board Work: Co-dominance and Blood Types(40) Who’s the Daddy? Genetics(10) Co-dominance Practice

I can:predict offspring ratios for co-dominant traits

CatalystHow many phenotypes do you see in incomplete dominance? How does the heterozygote compare to the homozygotes?Show all steps. Blue beetles and yellow beetles mate to produce green beetles. What is the likely outcome of a cross between a green beetle and a blue one?

HW: Co-dominance Practice

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Exit Ticket Review1. In mice, a certain species displays incomplete dominance in coat coloring. The offspring of a black (BB) mouse and a white (bb) mouse are gray (Bb) mice. A cross between two gray mice will most likely produce offspring with which percent of coat colors?

A. 25% black, 75% gray B. 25% gray, 75% white C. 25% white, 25% black, 50% gray D. 25% gray, 25% black, 50% whiteDraw a completed Punnett Square for the problem above.

B

B

b

b

BB

Bb

Bb

b

b

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Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.

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Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.

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Co-dominance

is a pattern of inheritance in which both dominant alleles contribute to the phenotype. The heterozygous phenotype shows both traits.

B = blackW = white

BWBBwhite

black

erminette

(black AND white)

When there are two dominant alleles in one genotype, both are expressed.

WW

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red cow + white cow = roan cow

(red and white)

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B = blackW = white

Coat color in mice exhibits co-dominance.

BB

?black

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B = blackW = white

Coat color in mice exhibits incomplete dominance.

WW

?white

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B = blackW = white

Coat color in mice exhibits co-dominance.

BW

?checkered(black and white)

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R = red

B = blueRR

?

redFlowers exhibit co-dominance for petal color.

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R = red

B = blueBB

?

blueFlowers exhibit co-dominance for petal color.

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R = red

B = blueRB

?

red and blueFlowers exhibit co-dominance for petal color.

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R = red

W = whiteRR

?

redCow coat color follows a pattern of co-dominance.

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R = red

W = whiteWW

?

whiteCow coat color follows a pattern of co-dominance.

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R = red

W = whiteRW

?

roanCow coat color follows a pattern of co-dominance.

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The two alleles for fish scale color, red and yellow, are co-dominant. If a red fish mates with a speckled red-and-yellow fish, what percentage of their offspring will be yellow?

Solving

a Co-dominance

Problem

R

R

R

Y

R

R

R

R

R

Y

R

Y

1.

Read the problem. Underline the known alleles. Identify the type of inheritance as co-dominance.

3.

Circle and/or write down the genotypes of the parents.

4

.

Set up and solve

Punnett

Square.

5.

Highlight and answer what the question is asking.

2.

Choose a letter to represent each allele in the problem.

Y

= yellow;

R

= red

parents:

RR

x

R

Y

yellow

=

0/4

=

0%

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)Red flowers are crossed with white flowers. All the flowers produced are red.

How do you know what type of inheritance it is?

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)Red flowers are crossed with white flowers. All the flowers produced are pink.

How do you know what type of inheritance it is?

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)Red flowers are crossed with white flowers. All the flowers produced are speckled red-and-white.

How do you know what type of inheritance it is?

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)A black cat mates with a white cat. All of their children are white with black spots.

How do you know what type of inheritance it is?

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)A red flower is crossed with a yellow flower. All of the flowers produced are orange.

How do you know what type of inheritance it is?

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What type of inheritance? (Complete, Incomplete, or Co-Dominance)A red flower is crossed with a yellow flower. All of the flowers produced are red-and-yellow.

How do you know what type of inheritance it is?

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An important example of co-dominance AND multiple alleles is human blood groups. The proteins on the surface of red blood cells determine your blood type, and those are determined by genes.

both A and B proteins are expressed =

codominance!

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Human blood type is determined by 3 alleles (2 dominant, 1 recessive):

phenotypes:

IA

= IB = i =

type A (dominant)

type B (dominant)

type O (recessive)

Just like with any other trait, you must have two alleles for blood type. You still inherit one allele from each parent.

genotypes:

I

A

I

A

or

I

A

i

I

B

I

B

or

I

B

i

I

A

I

B

ii

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What’s the blood type?ii

type O

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What’s the blood type?IAi

type A

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What’s the blood type?IAIB

type AB

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What’s the blood type?IBIB

type B

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What’s the blood type?IAIA

type A

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What’s the blood type?IBi

type B

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Write the genotype for the phenotype described:heterozygous type A

IAi

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Write the genotype for the phenotype described:homozygous type B

IBIB

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Write the genotype for the phenotype described:homozygous type A

IAIA

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Write the genotype for the phenotype described:heterozygous type B

IBi

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Write the genotype for the phenotype described:type O

ii

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Write the genotype for the phenotype described:type AB

IAIB

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Write the genotype(s) for the phenotype described:type A

IAIA or IAi

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Write the genotype(s) for the phenotype described:type B

IBIB or IBi

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Solving Blood Type ProblemsA woman who is heterozygous for blood type B has a child with a man with heterozygous type A blood. What are the possible genotypes of their children?