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Genetics > Unit 2 > Flashcards

Unit 2 Flashcards

1
Q

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

A

True (AH Sturtevant)

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2
Q

.378 % recombinants would be how many MUs?

A

37.8 MUs, or 37.8 cM

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3
Q

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

A

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

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4
Q

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

A

interference

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5
Q

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

A

50%

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6
Q

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

A

No Recomb

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7
Q

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…

A

Recomb

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8
Q

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

A

3

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9
Q

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

A

True

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10
Q

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)

A

Curt Stern

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11
Q

What could produce the mosaic pattern seen in the flies?

A

chromosomal nondxjt or chromosomal loss during mitosis

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12
Q

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

A

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

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13
Q

name this protein important to cell cycle control which supresses tumors

A

Rb protein, a tumor supressor gene

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14
Q

loss of Rb protein/inactivation free what?

A

EF2, stimulates proliferation

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15
Q

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

A

True

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16
Q

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

A

6q21

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17
Q

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.

A

C

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18
Q

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.

A

D

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19
Q

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

A

E

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20
Q

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.

A

False

True

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21
Q

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.

A

E

22
Q

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

A

false

23
Q

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:

A

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

24
Q

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

A

metacentric

25
Q

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

A

yes

26
Q

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

A

T

27
Q

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

A

True

28
Q

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

A

D

29
Q

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

A

cystic fibrosis

30
Q

probability-based method for ascertaining linkage in human pedigree analysis

A

lod score

31
Q

results from branch migration during recombination

A

heteroduplex

32
Q

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

A

genomic imprinting

33
Q

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

A

cis or coupling configuration

34
Q

tumors can arise through mitotic recomb in mutant heterzygotes

A

RB gene

35
Q

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

A

colchine

36
Q

multiple phentypic effects caused by a single gene

A

pleitropy

37
Q

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

A

mitogen
colchicine
hypotonic solution

38
Q

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

A

G-banding

39
Q

pretreatment by high temps and controlled pH; staining with Giemsa

A

R-banding

40
Q

More bands at metaphase or prometaphae?

A

prometaphase 1500>300

41
Q

Y heterochromatin would be described as …

A

constitutive heterochromatin (always genetically inactive)

42
Q

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

A

True

43
Q

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

A

Mary Lyon

44
Q

mosaicism is a result of ?

A

early and random inactivation of X cmsm

45
Q

formed as a result of developmental event…X cmsm inactivation

A

Faculative heterochromatin

46
Q

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

A

epigenetic modifications

47
Q

dosage compensation in flies:

A

male X twice as active

48
Q

dosage compensation in worms

A

female X half as active

49
Q

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

A

Prader-Willi Syndrome

50
Q

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

A

methylation of DNA

51
Q

treatment often used to produce polyploidy in plants

A

colchicine

52
Q

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

A

e

Genetics (6 decks)

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