Unit 2

Question 1

T/F: Number of crossovers is directly proportional to distance between gene loci

Answer 1

True (AH Sturtevant)

Question 2

.378 % recombinants would be how many MUs?

Answer 2

37.8 MUs, or 37.8 cM

Question 3

Who’s lab showed linkage experiments in Drosophilia support cmsm theory of inheritance?

Answer 3

TH Morgan
genes are linked through generations-no random mixing
Genes are arrayed in a linear order along the length of a chromosome.
Homologs carry the same array of gene loci, but not necessarily the same alleles

Question 4

Evidence that crossing-over in one area can decrease the likelihood of an exchange in an adjacent area

Answer 4

interference

Question 5

if genes are located far apart on the same chromosome, what would we expect RF to be?

Answer 5

50%

Question 6

A 4:4 pattern indicates RECOMBINATION/NO RECOMBINATION has occurred between the centromere and the gene in question

Answer 6

No Recomb

Question 7

A 2:2:2:2 pattern or a 2:4:2 pattern indicates RECOMBINATION/NO RECOMBINATION has occurred between the centromere and the gene in question…

Answer 7

Recomb

Question 8

When two pairs of alleles are segregating, how many asci patterns are possible…

Answer 8

3

Question 9

T/F: If A and B loci are linked, PD»NPD

Answer 9

True

Question 10

In 1936, who demonstrated somatic cell crossing over during development
Studied the X-linked genes yellow and singed
y+ sn/y+ sn females x y sn+/Y males
(singed females x yellow males)

Answer 10

Curt Stern

Question 11

What could produce the mosaic pattern seen in the flies?

Answer 11

chromosomal nondxjt or chromosomal loss during mitosis

Question 12

adjacent patches of both yellow cuticle and signed bristles (twin spots) could only arise if…

Answer 12

both patches of mutant tissue arose from the same event…crossing over during mitosis

Question 13

name this protein important to cell cycle control which supresses tumors

Answer 13

Rb protein, a tumor supressor gene

Question 14

loss of Rb protein/inactivation free what?

Answer 14

EF2, stimulates proliferation

Question 15

T/F: Heterozygotes for an RB gene mutation are at increased risk of retinal cancer…

Answer 15

True

Question 16

The gene for the enzyme superoxide dismutase II is located at band 1 in region 2 on the long arm of chromosome 6. This would be abbreviated

Answer 16

6q21

Question 17

In analyzing a human karyotype:
a) test results can be obtained in several hours, using mitotic cells taken directly from blood; b) all chromosomes are easily identified simply on the basis of size and centromere position; c) colchicine is added to arrest cells in metaphase; d) all of the above; e) none of the above.

Answer 17

C

Question 18

The successful mapping of a gene to a human chromosome by somatic cell hybridization requires that:
a) the parental cells will be preferentially killed in a selective media; b) human chromosomes are randomly lost from the hybrid cells; c) the human gene products can be identified in hybrid cells; d) all of the above; e) none of the above.

Answer 18

D

Question 19

In Neurospora, a first division segregation pattern:
a) represents a single crossover between a gene and the centromere; b) identifies a recombinant ascus; c) will produce non-parental ditype asci; d) all of the above; e) none of the above

Answer 19

E

Question 20

True or false. The Delbruck-Luria fluctuation test is a probability technique designed to aid in assembling linkage information from human pedigree data.
True or false. In most organisms, mutation rates are harder to measure than mutation frequencies.

Answer 20

False

True

Question 21

The idea that genes control the ability to produce enzymes was first suggested from observations in which organism?
a) pea plants; b) fruit flies; c) E. coli; d) mice; e) humans.

Answer 21

E

Question 22

True or false: All genes located on the same chromosome must be within 50 map units of one another.

Answer 22

false

Question 23

What is important to know about this question?
A geneticist crosses two yellow mice with straight hair and obtains the following progeny: ½ yellow, straight; 1/6 yellow, fuzzy; ¼ agouti, straight; 1/12 agouti, fuzzy. This cross indicates:

Answer 23

YY are never born. YY is recessive lethal, so yellow mice are obligate heterozygotes Yy

Question 24

If a cmsm has arms of equal length is is termed?

Answer 24

metacentric

Question 25

If genes are linked, would they be on the same chromosome homolog?

Answer 25

yes

Question 26

Regarding the Xist pic: T/F: Once a specific Xist DNA locus is expressed, all progeny of that cell will express the same locus; ie the decision will be clonally propagated

Answer 26

T

Question 27

T/F regarding …if the DNA in the electrophoretic gel used in this experiment was visualized with a fluorescent dye, no clear individual bands would be visible, due to the large number of DNA fragments produced on digesting genomic DNA

Answer 27

True

Question 28

RNA interference: a) can inhibit translation by leading to mRNA degradation; b) can inhibit translation by blocking ribosome movement c) was discovered first in nematodes, leading to the Nobel Prize d) all of the above

Answer 28

D

Question 29

one of the first genes to be localized using linkage to a polymorphic DNA marker locus

Answer 29

cystic fibrosis

Question 30

probability-based method for ascertaining linkage in human pedigree analysis

Answer 30

lod score

Question 31

results from branch migration during recombination

Answer 31

heteroduplex

Question 32

epigenetic activation of specific genes depending on the parent that transmits them

Answer 32

genomic imprinting

Question 33

where wild type genes at linked loci are found on the same homolog in a heterozygote

Answer 33

cis or coupling configuration

Question 34

tumors can arise through mitotic recomb in mutant heterzygotes

Answer 34

RB gene

Question 35

drug used to increase the number of cells in metaphase in karyotype analysis

Answer 35

colchine

Question 36

multiple phentypic effects caused by a single gene

Answer 36

pleitropy

Question 37

how do we examine human tissues for cmsm abnormalities?
Peripheral WBCs must be stimulated by ? to divide…
? increases number of cells at metaphase plate
? aids in spreading chromosomes

Answer 37

mitogen
colchicine
hypotonic solution

Question 38

pretreatment by 1)concentrated salt solutions at high temps (eg 60 C) or 2) proteloytic enzymes

Answer 38

G-banding

Question 39

pretreatment by high temps and controlled pH; staining with Giemsa

Answer 39

R-banding

Question 40

More bands at metaphase or prometaphae?

Answer 40

prometaphase 1500>300

Question 41

Y heterochromatin would be described as …

Answer 41

constitutive heterochromatin (always genetically inactive)

Question 42

T/F: number of Barr bodies observed is one less than the number of X chromosomes

Answer 42

True

Question 43

Who experiemented with sex linked coat color genes in mice, and discovered X inactivation?

Answer 43

Mary Lyon

Question 44

mosaicism is a result of ?

Answer 44

early and random inactivation of X cmsm

Question 45

formed as a result of developmental event…X cmsm inactivation

Answer 45

Faculative heterochromatin

Question 46

‘outside the genes alteration in DNA and associated protein leading to changes in gene expression - but potentially heritable

Answer 46

epigenetic modifications

Question 47

dosage compensation in flies:

Answer 47

male X twice as active

Question 48

dosage compensation in worms

Answer 48

female X half as active

Question 49

the result of inheriting a deletion on cmsm 15 when the deletion cmsm is contributed by the male and the female cmsm is “imprinted”

Answer 49

Prader-Willi Syndrome

Question 50

Inactivation seems to be associated with ____ of the imprinted site; this chemical tag may be a signal for deactivation/activation

Answer 50

methylation of DNA

Question 51

treatment often used to produce polyploidy in plants

Answer 51

colchicine

Question 52

Constitutive heterochromatin:

a) contains a greater region of genes than euchromatin
b) represents chromosomal regions that stain densely
c) is often found adjacent to the cmsm centrometers
d) a and b are correct
e) b and c are correct

Answer 52

e