Ch 6 Genetic Linkage and Mapping - Exam 2!

Question 1

Define a linkage group

Answer 1

group of genes that located on the same chromosome

Question 2

Linkage groups correspond to?

Answer 2

the number of haploid chromosomes

Question 3

When genes A and B are on two different chromosomes, gametes are produced in?

Answer 3

equal proportions

Question 4

When genes A and B are on the same chromosome and are very, very close together, this is known as __ __.

Answer 4

complete linkage

Question 5

When genes A and B are on the same chromosome and are very, very close together, gametes are produced in ?

Answer 5

equal proportions

Question 6

When genes A and B are on the same chromosome not so close, this is known as __ __

Answer 6

incomplete linkage

Question 7

Incomplete linkage produces gametes in?

Answer 7

unequal proportions

Question 8

When genes A and B are on the same chromosome and are very, very far apart, this is known as __ __ ___

Answer 8

complete incomplete linkage

Question 9

Complete incomplete linkage produces gametes in?

Answer 9

equal proportions

Question 10

What do new alleles often change?

Answer 10

activity of the cellular product of the gene; phenotype

Question 11

When genes are in lowercase form they are usually?

Answer 11

recessive mutations

Question 12

When genes are in uppercase form they are usually?

Answer 12

dominant mutations

Question 13

What were Morgan’s two key proposals?

Answer 13

crossing over occurs
closer the gametes, the less likely a chiasma forms

Question 14

Morgan proposed a __ array of genes on a chromosome

Answer 14

linear

Question 15

Recombinant frequency is dependent on?

Answer 15

distance between genes

Question 16

What is the equation for recombinant frequency (RF)?

Answer 16

of recombinant offspri5ng/ total # of offspring x 100%

Question 17

What does recominbant frequency provide information on?

Answer 17

The physical location of genes on chromosomes

Question 18

yy ww notates?

Answer 18

unknown linkage

Question 19

yw/yw notates?

Answer 19

loci on the same chromosome

Question 20

y/y w/w notates?

Answer 20

loci on different chromosomes

Question 21

Alleles can be __ or __ on the chromosome

Answer 21

cis; trans

Question 22

Define crossing over

Answer 22

physical exchange between non-sister chromatids of homologus chromosomes

Question 23

Crossing over occurs duing __ __ of ___

Answer 23

prophase I; meiosis

Question 24

When are two times crossing over is not detectable?

Answer 24

1. if it occurs outside the two gene markers region
2. If crossing over occurs and even number of times between the two marker genes

Question 25

T/F: crossing over occurs more randomly along the length of chromosome pairs.

Answer 25

True

Question 26

T/F: crossing over involves reciprocal exchange of unequal and corresponding segments

Answer 26

FALSE; equal

Question 27

T/F Multiple crosses are not possible in crossing over

Answer 27

false

Question 28

What is the purpose of genetic mapping?

Answer 28

to determine the gene loci on chromosomes

Question 29

If genes are far, there are __ recombinant offspring

Answer 29

many

Question 30

If genes are close, there are __ __ recombinant offspring

Answer 30

very few

Question 31

Map distance =

Answer 31

of total recombinant offspring / total # of offspring x 100

Question 32

1 map unit (mu) = _ centiMorgans (cM) = _% recombinant frequency

Answer 32

1;1

Question 33

What is a test cross?

Answer 33

heterozygous crossed with a recessive homozygous to determine an unknown genotype

Question 34

Recombinant offspring __ nonrecombinant offspring

Answer 34

<

Question 35

Genetic mapping utilizes a __ cross

Answer 35

test