Punnett SquaresAnd Meiosis!

Meiosis:A type of cell division in which a diploid cell(two copies of each gene) divides to form a haploid cell (one copy of each gene). = SPERM and EGG!

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Dominant T - curved thumb/allele Recessive t - not curvedallele

Dominant T - curved thumballele

Recessive t - not curvedallele

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Tt

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Tt

T

tT

t

Punnett Square: A method to determine the likely genotypes and phenotypes of offspring

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T

t

T

teggs

sperm

ttTt

TtTTCurved thumb

Straight thumbCurved thumb

Curved thumb

How to fill in a punnett square

Using the Punnett Square below, correctlycross a heterozygous brown haired person with a homozygous blonde haired person.          

Bb x bb

B = brown hair alleleb = blonde hair allele

B

b

b

b

bbBb

Bb bb

b b

B

b

Bb Bb

bb bb

Phenotype: 2 brown hair and 2 blonde hairGenotype: 2 Bb and 2 bb

Solve the following problems:GIVE THE PHENOTYPE & GENOTYPE!

Cross EE x ee (brown eyed person with blue eyed)

Cross a wrinkled seed with a homozygous round seed (W = wrinkled w = round)

Cross a heterozygous tall person with a heterozygous tall person.

Cross a homozygous tall person with a short person

Mendel’s Laws

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Law of Segregation

Two alleles separate from each other during meiosis!

Each homologous chromosome pair separates during the formation of the sperm and egg (meiosis!)

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Law of Segregation

Law of segregation

Incomplete Dominance Hh (heterozygote)

where the functioning allele makes less protein

Example: in snapdragon flowers, red is dominant, but less protein pigment is made w/ Rr; the flower is pink (Rr) = pink

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Incomplete Dominance Practice

In the budgerigars bird (“budgie”), olive feather color is dominant (GG), dark green is heterozygous (Gg), and light green is recessive (gg).

Cross an olive bird and a light green bird.

Cross two heterozygous birds

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Codominance When both alleles

(forms of a gene) are expressed

Blood type is an example of codominance

Blood type A is codominant with B

Blood type O is recessive to A and B

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Codominance Practice Cross a person with

type O blood (oo) with a person who has type A blood (Ao).

What are the possible genotypes and phenotypes of their children?

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G: 2 Ao: 2 oo P: 2: type A blood : 2 type o blood

Sex-Lined Traits gene carried only

on the X chromosome

there is no corresponding gene on the y chromosome

Cross a non-colorblind male (XBY) with a “carrier” female (XBXb)

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Law of Independent Assortment

The distribution of alleles for one trait does not affect the distribution for of alleles for other traits

Law of Independent Assortment

Law of Independent Assortment

Law of Independent Assortment