Mandelian Genetics

Question 1

___(scientist)___ bred pea plants and studied the patterns of inheritance.

Answer 1

Gregor Mendel

Question 2

Each chromosome contains DNA segments that code for the basic units of heredity and are transmitted from one generation to the next. These DNA segments are called ______.

Answer 2

genes

Question 3

Each gene has its own location on a chromosome called a gene _______.

Answer 3

locus

Question 4

What is the difference between a genotype and phenotype?

Answer 4

A genotype is the genes making you up

A phenotype is the physical and physiological traits of an organism. (the observable traits)

Question 5

What is the Law of Segregation?

Answer 5

when gametes (egg or sperm) are made, the two traits carried by each parent separate.

Question 6

Define Mendel’s Second Law: Law of Independent Assortment

Answer 6

Genes located on different chromosomes assort independently of each other.

In other words, during the forming of gametes the alleles for height segregate independently from the alleles for a trait such as color. The genes for height and color are on different chromosomes and will assort independently.

The closer the genes are located on a chromosome, the more likely they will be linked. Genes on the same chromosome are said to be linked genes.

Question 7

What is the difference between incomplete dominance and codominance?

Answer 7

Incomplete dominance will show a “blended” phenotype (red + white = pink)

Codominance: If a person has AB blood type, one parent gave A and the other parent gave B.

The A and B alleles are said to be codominant

Question 8

An ______ gene is a gene that covers up the expression of another gene in the phenotype.

Answer 8

epistatic

eg. In Labrador Retrievers, we see many different colored dogs.

Question 9

What does pleiotropy refer to?

Answer 9

a SINGLE gene that can affect an organism in various ways.

eg. in sickle cell anemia, a single mutation occurs, and gives rise to a defective hemoglobin molecule

Question 10

Describe polygenic inheritance:

Answer 10

In polygenic inheritance we see TWO or MORE genes contributing to a single trait. Hair color, skin color, and height result from the interactions of several genes.

Question 11

Describe the term Multiple alleles:

Answer 11

When a gene has more than two given alleles

eg. blood type ABO

Question 12

What antigens and antibodies are present in the following?

Blood type: A
Blood type: B
Blood type: AB
Blood type: O

Answer 12

Blood type: A (A antigen and B antibody)

Blood type: B (B antigen and A antibody)

Blood type: AB (A and B antigens and NO antibodies)

Blood type: O (NO ANTIGENS but A and B antibodies)

“THIS IS AN IMPORTANT DAT TOPIC, MAKE SURE YOU UNDERSTAND THIS”

Question 13

Females (mammals) have 1 chromosome that is inactivated in embryonic development by methylation… called a _______.

Answer 13

Barr body

Question 14

Males are hemizygous… meaning they contain ____.

Answer 14

XY

Question 15

What is the difference between alleles in a female who is colorblind and a female who is just a carrier?

Answer 15

Colorblind female: Xc, Xc

Female carrier: Xc, X

(A colorblind female will have the allele on both X chromosomes)

Question 16

What is the difference between autosomal recessive and autosomal dominant?

Answer 16

Autosomal recessive skips generations!!!

Autosomal dominant: If one gene is affected (X Xc), you have the disease. (does NOT skip generations)

Question 17

Males give sex-linked genes to their _______.

Females give sex-linked genes to both sons and daughters.

A male gets a sex-linked disease from his ______.

Answer 17

Males give sex-linked genes to their daughters. not their sons

Females give sex-linked genes to both sons and daughters.

A male gets a sex-linked disease from his mother.

Question 18

The probability of a ______ is proportional to the distance separating the genes!!

Answer 18

crossover

Question 19

An offspring containing the wrong number of chromosomes as seen in Down syndrome is referred to as ____________.

Answer 19

Aneuploidy

Question 20

Discuss each of the following:

• Down syndrome
• Turner syndrome
• Kleinfelter syndrome

Answer 20

Down syndrome: Trisomy 21

Turner syndrome: female that is just 1 X (not XX)

Kleinfelter syndrome: a male with XXY

Question 21

Give examples of polyploidy:

Answer 21

polyploidy is very common in plants. We see a 3N or 4N cell

Many weeds, and dandelions are polyploidy

Endosperm of plant seeds: 3N

Human liver cell are occasionally 3N, 4N, etc.!!!!

Question 22

A deleted chromosome fragment is joined to a nonhomologous chromosome. This is referred to as ______.

Answer 22

Translocation

The key word here is nonhomologous

Question 23

How many gametes can be made given the following genotype: Xx Yy Zz WW BB

Answer 23

2^n

n = number of heterozygotes

2^3 = 8

“THE DAT LOVES THIS TYPE OF PROBLEM!”