Chapter 6 - Genetic Linkage and Mapping in Eukaryotes

Question 1

How is the law of independent assortment violated?

Answer 1

Transmission of genes close to each other on the same chromosome

Question 2

When two or more genes are located on the same chromosome and physically linked

Answer 2

Synteny

Question 3

When genes close together on a chromosome are transmitted as a unit

Answer 3

Genetic linkage

Question 4

Chromosomes are called…

Answer 4

Linkage groups

Question 5

Study of linkage between two genes

Answer 5

Two-factor cross

Question 6

Study of linkage between three genes

Answer 6

Three-factor cross

Question 7

Genes that are far apart on the same chromosome can independently assort due to…

Answer 7

Crossing over

Question 8

Suggested that the transmission of two traits from parents could be somewhat coupled

Answer 8

Bateson and Punnett

Question 9

Replicated sister chromatid homologues associate as

Answer 9

Bivalents

Question 10

Crossing over may produce

Answer 10

Recombinant genotypes

Question 11

Haploid cells that contain a combination of alleles NOT found in the original chromosomes

Answer 11

Recombinant cells

Question 12

Produced during the exchange of DNA between two homologous chromosomes during meiosis in one or both parents to create a novel combination of genetic material

Answer 12

Recombinant offspring

Question 13

First direct evidence of linkage came from studies by

Answer 13

Thomas Hunt Morgan

Question 14

Conducted experiments involving two linked genes to obtain evidence that genetic recombination comes from crossing over

Answer 14

Creighton, McClintock and Stern

Question 15

The specific location a gene is on a chromosome

Answer 15

Locus

Question 16

Used to determine that linear order of linked genes along the same chromosome

Answer 16

Genetic mapping

Question 17

Uses of genetic mapping

Answer 17

Understanding complexity, cloning, understanding of evolution, diagnosis of disease, odds of having children with a disease, and improvement of agriculturally important strains

Question 18

What is the relative distance between linked genes based on

Answer 18

The likelihood that a crossover would occur

Question 19

Percentage of recombinant offspring is correlated to

Answer 19

The distance between the two genes

Question 20

Genes that are far apart result in

Answer 20

Many recombinant offspring

Question 21

Close genes result in

Answer 21

Few recombinant offspring

Question 22

Map distance equals

Answer 22

Percentage of recombinant offspring out of total offspring

Question 23

Units of map distance

Answer 23

Map units, centiMorgans

Question 24

A testcross is expected to yield a maximum of…

Answer 24

50% recombinant offspring

Question 25

Separates the gene in the middle from the other two genes at either end

Answer 25

Double crossover

Question 26

When a first crossover decreases the probability that a second will occur nearby

Answer 26

Interference

Question 27

Equation for interference

Answer 27

I = 1-C

Question 28

What does C represent

Answer 28

Coefficient of coincidence

Question 29

Equation for C

Answer 29

Observed number of double crossovers / expected number of double crossovers

Question 30

Haploid cells reproduce...

Answer 30

Asexually

Question 31

In Ascomycetes, meiosis produces four haploid cells called...

Answer 31

Spores

Question 32

A group of 4 spores is a...

Answer 32

Tetrad

Question 33

The spores are enclosed in a sac called an...

Answer 33

Ascus

Question 34

Tetrad may contain four haploid cells with nonrecombinant arrangements of alleles

Answer 34

Parental ditype

Question 35

An ascus may have two nonrecombinant cells and two recombinant cells

Answer 35

Tetratype

Question 36

An ascus with a nonparental ditype contains...

Answer 36

Four cells with recombinant genotypes

Question 37

If the two genes assort independently...

Answer 37

50% recombinant spores are produced

Question 38

If the two genes are linked...

Answer 38

The type of crossover between them determines what type of ascus is produced

Question 39

The nonparental ditype can only be produced from...

Answer 39

Double crossover

Question 40

Crossing over in mitosis is expected to be much less likely than during meiosis, producing a new combination of alleles

Answer 40

Mitotic recombination

Question 41

If mitotic recombination occurs during an early stage of embryonic development...

Answer 41

Daughter cells containing recombinant chromosomes continue to divide which can result in a patch of tissue with different characteristics than the rest of the organism

Question 42

Who discovered changes from mitotic recombination?

Answer 42

Curt Stern