+

Genetics Review

+In pigs, the dominant trait is short snouts. Using the letter “N,” write the three possible genotypes for pigs. Then, write the matching phenotypes for those genotypes.

NN = Short snoutNn = Short snoutnn = Long snout

+Identify the following as homozygous or heterozygous:(1) AA (4) jj(2) Hh (5) Pp(3) RR (1)Homozygous

(2)Heterozygous(3)Homozygous(4)Homozygous(5)Heterozygous

+1) What does it mean for a trait to be dominant?

2)What is the only way for a recessive trait to show in an organism’s phenotype?

Dominant traits overpower or cover-up the recessive trait. Dominant traits occur more often in an organism.

The only way for a recessive trait to show up is for BOTH alleles in the organism to be recessive. The recessive traits have to “gang up” together to show through. For example: ff – both alleles (letters) in the genotype are recessive.

+1) What does DNA stand for?

2) What is the shape of DNA?

3) Where is DNA found in a cell?

4) What does RNA stand for?

5) Where does our DNA come from?

Deoxyribonucleic Acid

Double Helix

Nucleus

Ribonucleic Acid

Our parents – half from mom and half from dad

+In tigers, long claws are a dominant trait over short claws. A female tiger, who is heterozygous, has offspring with a male tiger who has short claws. Complete the Punnett Square.

C c

c

c

Cc cc

Cc cc

+In leprechauns, having pointy ears is a dominant trait. A female leprechaun that is homozygous for the dominant trait has offspring with a male leprechaun who is homozygous for the recessive trait. Complete a Punnett square to show their possible offspring.E E

e

e

Ee Ee

Ee Ee

+In tulips, the color red is a recessive trait and the color white is the dominant trait. A white tulip (Ww) is crossed with a red tulip. Create a Punnett Square to predict the color of the plants created from the cross. W w

w

w

Ww ww

Ww ww

+In the Simpson family, yellow skin is the dominant trait. If Lisa (YY) marries a boy from another town who has pink skin (yy), what would be the probability of their offspring having yellow skin? Create a Punnett Square to show your work. Y Y

y

y

Yy Yy

Yy Yy

+Two dogs have a litter of puppies. All of the puppies are heterozygous, showing the dominant trait of brown hair. What must the genotypes of the parents be?

b b

B

B

Bb Bb

Bb Bb

+In mice, the dominant color is brown. The recessive color is tan. Two mice, that are both brown, have a baby mouse that is tan. What must the genotypes of the parents be for this to occur?B b

B

b

BB Bb

Bb bb