PUNNETT SQUARES AND MORE

Chapter 9 Review

Define genotype.

The genetic makeup of an organism

Define allele.

An alternate form of a gene.

Define recessive.

An allele that is hidden unless there are two of them

Define dominant.

An allele that is fully expressed, it determines the phenotype of an organism.

What word refers to the physical appearance of an organism?

Phenotype

When doing a test cross, an organism with unknown genotype is mated with one…

That is homozygous recessive for a trait

What is a carrier?

Someone heterozygous for a disease that shows no symptoms but CAN pass it on to offpsring.

John is blind, which is recessive. His parents are NOT blind. What are their

genotypes? John’s?

Parents: Heterozygous (for example: Bb)John: homozygous recessive (bb)

Name some recessive disorders.

DeafnessAlbinismCystic FibrosisPKU Sickle CellTay Sachs

Name some dominant disorders.

DwarfismAlthzimersHuntington’s diseaseHigh (hyper) cholesterol

Name some sex linked disorders.

Color blindnessBaldnessHemophiliaMuscular dystrophy

If both alleles are expressed when someone is heterozygous, we call this ______.

Codominance

What are the sex chromosomes of a man?

XY

Is blood type codominance or incomplete?

Codominance

How many sex chromosomes are in a sperm?

One, either X or Y

Genes located on sex chromosomes are called

Sex linked genes

Why do men get sex linked genes more often than women?

Men only need to have one recessive allele (on their one X gene) in order to get the condition. Women have to inherit 2, one on each X.

What’s the name of the monk and what did he study?

Gregor Mendelpeas

What is heterozygous?

Two different alleles for the same trait, one dominant and one recessive, written Bb.

What are the 3 types of fetal screening?Which is the LEAST invasive?

Ultrasound, CVS, amniocentesisUltrasound

Skin color, due to many genes, is caused by

Polygenic inheritance

Brown eyes (B) are dominant to blue (b). What is the genotype of a heterozygous

person.

Bb

Brown eyes are dominant (B) to blue (b). White hair (W) is dominant to gray (w).

What’s the genotype of blue eyes and grey hair?

bbww

Brown eyes are dominant (B) to blue (b). White hair (W) is dominant to gray (w).

genotype. Bbww =

Brown eyes, gray hair

Purple flowers are dominant to white. Cross 2 heterozygous flowers. What’s the probability of a

white flower?

1/4

Purple flowers are dominant to white. Cross a heterozygous with a white. What’s the probability of

a white flower?

1/2

Purple flowers are dominant to white. Cross two homozygous purple flowers. What’s the probability

of a white flower?

0

Brown eyes are dominant. A blue eyed child has brown eyed parents. What are their genotypes?

Bb and Bb

Brown eyes are dominant to blue. Two heterozygous parents have a child. What is the probability that the child will have

brown eyes?

3/4

Tall plants are dominant to short. A homozygous tall and short plant are crossed. What is the expected

phenotypic ratio

4/4 tall

Purple flowers are dominant to white. Cross a heterozygous with a white. If there are 400 babies,

how many will be white?

200

Incomplete dominance: Red (RR), Pink (Rr), white (rr). Cross a red and white and show your phenotypic

ratio.

4/4 pink

Incomplete dominance: Red (RR), Pink (Rr), white (rr). Cross two pinks. How many offspring will be

red?

¼ red

Incomplete dominance: Red (RR), Pink (Rr), white (rr). Cross 2 pinks and show the phenotypic ratio

1 red: 2 pink: 1 white

Incomplete dominance: Red (RR), Pink (Rr), white (rr). Cross 2 pinks and show the genotypic ratio

1 RR: 2 Rr: 1 rr

A man has heterozygous B blood, a woman has heterozygous A blood. What can their children have?

A, B, AB, or O

Mom has type A blood. Baby has type O. Dad 1 has type AB and Dad 2 has type A. Who is the baby

daddy?

Dad 2

A person with type AB can receive what blood types?

Any, AB is the universal receiver

O is the universal donor.

Color blindness is sex-linked. Cross a normal man with a carrier woman. What are the chances a son

will be blind?

1/2

Color blindness is sex-linked. Cross a normal man with a carrier woman. What are the chances a daughter will

be blind?

0

Color blindness is sex-linked. Cross a blind man and a carrier. What are the chances a daughter will be a

carrier?

1/2

Color blindness is sex-linked. Cross a blind man and a blind woman. What are the chances a daughter

will be blind?

100%

Long (L) is dom to short (l) and yellow (Y) is dom to green (y). Cross a homozygous long heterozygous

yellow with a short ?heterozygous yellow bird. How many are LlYy?

8/16

Using the same results, what proportion of offspring will have long yellow feathers?

12/16

Dark (D) is dom to light and Brown (B) is dom to blue. Cross two people heterozygous for BOTH traits.

What is the prob of a light brown eyed child?

3/16

Dark (D) is dom to light and Brown (B) is dom to blue. Cross a heterozygous dark heterozygous brown with a light heterozygous brown. Show phenotypic

ratios.

6/16 dark brown, 6/16 light brown, 2/16 dark blue, 2/16 light blue

In pedigrees, circles represent

women

A filled in circle or square means

Someone has the condition or diseaseGenotype is homozygous recessive (aa)

Horizontal lines between people indicate

They are married or have offspring together