Non-Mendelian genetics

Question 1

What is the notation used in Morgans experiments?

Answer 1

We name these alleles based on the mutation being observed. The mutation gets a lower case letter and the wild type uses the same lower case letter with a + superscript.

Question 2

What were Morgan’s big contributions?

Answer 2

genes are on chromosomes
sex-linkage
Crossing over of chromosomes

Question 3

What is a sex-linked trait?

Answer 3

Sex-linked traits are found on the X chromosome, in organisms that use X and Y chromosomes.

Question 4

The Y chromosome dictates “______.”

Answer 4

male

Question 5

What disorders are recessive and carried on the X chromosome?

Answer 5

Color blindness
Duchenne muscular dystrophy
Hemophilia

Question 6

If a female is heterozygous for a particular gene located on the X chromosome, she will be a ________ for that character.

Answer 6

mosaic

Question 7

What are linked genes?

Answer 7

Genes located on the same chromosome that tend to be inherited together are called linked genes. They do not separate from each other if no crossing-over occurs between them.

Question 8

The closer genes are to each other on the same chromosome, the _______ likely they are to become separated during crossing over, resulting in more parental phenotypes than predicted.

Answer 8

less

Question 9

The farther apart two genes are:
The _______ the probability that a crossover will occur between them;
The _______ the recombination frequency.

Answer 9

higher

higher

Question 10

What is a linkage map?

Answer 10

a genetic map of a chromosome based on recombination frequencies

Question 11

What are the four types of changes to chromosomal structure?

Answer 11

Deletion
Duplication
Translocation
Inversion

Question 12

What is nondisjunction?

Answer 12

When entire chromosomes can end up in the wrong cell during meiosis.

Question 13

What is aneuploidy? What causes it?

Answer 13

Caused by nondisjunction. The cells that result will have either one extra or one too few chromosomes. When these cells participate in fertilization, we call the resulting wrong number of chromosomes aneuploidy.

Question 14

What are trisomic and monosomic zygotes?

Answer 14

A trisomic zygote has three copies of a particular chromosome
A monosomic zygote has only one copy of a particular chromosome

Question 15

What is polyploidy? Is it common or rare?

Answer 15

a condition in which an organism has more than two complete sets of chromosomes. It is common in plants, but extremely rare in animals.

Question 16

Down syndrome is an ______ condition that results from three copies of chromosome __.

Answer 16

aneuploid

21

Question 17

What syndromes result from nondisjunction of sex chromosomes?

Answer 17

Klinefelter syndrome is the result of an extra chromosome in a male, producing XXY individuals.
Monosomy X, called Turner syndrome, produces X0 females, who are sterile; it is the only known viable monosomy in humans .

Question 18

What are the two exceptions to Mendelian genetics?

Answer 18

One exception involves genes located in the nucleus, and the other exception involves genes located outside the nucleus

Question 19

What is genomic imprinting?

Answer 19

Genomic imprinting involves the silencing of certain genes that are “stamped” with an imprint during gamete production
the phenotype depends on which parent passed along the alleles for those traits