Monday 1/27/14

• Grab a Bellwork sheet and begin on this problem.

• Incomplete Dominance • In 4 o'clock flowers, the alleles for red and

white flowers show incomplete dominance (RR=red, WW=white, RW=pink). What would be the possible outcomes of a cross between a pink flower and a pink flower?

Today

• Punnett square mastery• Dihybrid cross• Blood Types• Quiz on Friday 1/31

Using Letters

• Complete Dominance– Use same letter as capital and lowercase• Ex. T – dominant t – recessive• Ex. R – dominant r – recessive

• Incomplete Dominance/Codominance– Use only capital letters!! Use different letters for

each allele• Ex. R – Red W – White• Ex. B – Brown T - Tan

Genotype/Phenotype

GG GG

Gg Gg

G G

G

g

Genotype = 2GG: 2Gg: 0gg

Phenotype = 4 Green pea plants: 0 yellow plants

A green pea plant (GG) is being crossed with a green pea plant (Gg). Yellow is the recessive color

Genotype/Phenotype

BB Bb

Bb bb

B b

B

b

Genotype = 1 BB: 2Bb: 1 bb

Phenotype = 3 White rabbits: 1 brown rabbit

Two heterozygous white (brown fur is recessive) rabbits are crossed

Chickens!

• In some chickens, the gene for feather color is controlled by codominance. The allele for black isB and the allele for white is W. The heterozygous phenotype is known as erminette.

• a. What is the genotype for black chickens? ____b. What is the genotype for white chickens? ____c. What is the genotype for erminette chickens? ____

• What would the offspring look like when crossing an erminette chicken and a black chicken?

Co-dominance

• In shorthorn cattle, when a red bull (RR) is crossed with a white cow (WW), all the offspring are roan— a spotted, red and white or milky red color.

• 1. What offspring are expected from mating a roan bull and a roan cow?

• 2. What phenotypes would you expect from a cross between a red bull and a white cow?

2 generations

• A pea plant homozygous dominant (RR) for round seeds is crossed with a homozygous recessive (rr) wrinkled seeds pea plant. What is the phenotype of the offspring?

• The above offspring were allowed to self-pollinate and produce offspring of their own. What are the genotypes and the phenotype ratio of this F2 generation?

Books

• Read page 317 in your books.

Dihybrid crosses

• A pea plant that is tall (TT) and has round seeds (RR) is crossed with a short plant (tt) with wrinkled seeds (rr). – What are the genotypes of the parents?– What are the possible combinations of alleles for

each parent? – What will be the genotype and phenotype ratio for

this cross? – This F1 generation is allowed to self pollinate and

creates an F2 generation. What are the phenotypes?

Tuesday 1/28/14

• In some cats the gene for tail length shows incomplete dominance. Cats with long tails and cats with not tails are homozygous for their respective alleles. Cats with one long tail allele and one no-tail allele have short tails. What are the offspring of a cross between a short tail cat with a no-tail cat?

• Draw a punnett square and list the genotypes and phenotypes.

Today

• More dihybrids• Sex linked and Multiple allele• Activity• Quiz on Friday

Homework from yesterday

Another cross

• A tall white (Ttrr) plant is crossed with a short red (ttRR) plant. – What are the combinations of alleles for each

parent?– What are the genotypes and what is the

phenotype ratio for this cross?

Blood Types

• Human Blood types follow a pattern of Codominance.

• There are two dominant alleles IA and IB.• There is one recessive allele i

Blood Type (Phenotype)

GenotypeCan donate blood to:

Can receive blood from:

O ii A,B,AB and O(universal donor)

O

AB IAIB O, AB A,B,AB and O(universal receiver)

A IAIA or IAi AB, A O, A

B IBIB or IBi AB, B O, B

ABO

• What are the possible blood types from a cross between a heterozygous A man and a heterozygous B woman?

Sex Linked Inheritance

• Genes located on a sex chromosome.– Males XY– Females XX

• Genes on Y chromosome only passed from father to son.

• Genes on X chromosome are found in both sexes. Men have only 1 X chromosome.

Color Blindness

• Females have 3 genotypes and phenotypes:– XHXH is normal female without disorder– XHXh is female who is a “carrier”– XhXh is female who has the disorder

• Males have 2 genotypes and phenotypes– XHY is a normal male without disorder– XhY is male who has disorder

• What are the genotypic and phenotypic ratios for a cross between a “carrier” female and normal male?

Problems

• Work with your table partner to solve the problems on the half-sheets.

• I will hand out these out.

Face Lab