Exam 2

Question 1

when does crossing over occur

Answer 1

prophase 1

Question 2

what happens in meiosis 2 with normally-linked genes

Answer 2

they assort independently and end up in different gametes

Question 3

what happens if there is no crossing over in meiosis 1

Answer 3

there will be no recombinant gametes…they will all be parental

Question 4

single crossover

Answer 4

50% parental, 50% recombinant

Question 5

recombination frequency equation

Answer 5

number of recombinant progeny/all progeny x 100

Question 6

% recombination white eyes yellow bodies

Answer 6

1.5%

Question 7

% recombination yellow bodies cut wings

Answer 7

17.7%

Question 8

% recombination yellow bodies vermillion eyes

Answer 8

34.5%

Question 9

what is a test cross

Answer 9

crossing an F1 with a homozygous recessive

Question 10

is there recombination in male drosophila

Answer 10

no

Question 11

why do male drosophila not have recombination

Answer 11

they don’t form synaptonemal complexes

Question 12

what is responsible for breakage of chromosomes during crossing over

Answer 12

something-ase. protease?

Question 13

can sister chromatids have crossover

Answer 13

they can but wouldn’t do anything?

Question 14

double crossover - 2 strands

Answer 14

2 crossovers occurring, all parental chromosomes

Question 15

triple crossover

Answer 15

three crossovers occurring on the four strands

Question 16

quadruple crossover

Question 17

double crossover - 3 strands

Answer 17

half parental, half recombinant

Question 18

double crossover - 4 strands

Answer 18

all recombinant

Question 19

% recombination white eyes mini wings

Answer 19

31.5%

Question 20

% recombination yellow body rudimentary wings

Answer 20

50%

Question 21

explain theoretical vs empirical map distances

Answer 21

theoretical map distance for percent recombination is always higher than empirical

Question 22

over what distance is percent recombination a good estimate

Answer 22

short distances: less than 25 MU

Question 23

over what distance is percent recombination a bad estimate

Answer 23

long distances: over 35 MU

Question 24

are far apart genes likely to be linked?

Answer 24

no

Question 25

how can you find the number of recombinant offspring in a cross

Answer 25

divide recombinant by 2 and excess by two and multiply proportion by whole number of progeny to get estimate.

Question 26

calculating recombinant percent from first gene to middle gene

Answer 26

R1 + R1 + D + D / total # x 100

Question 27

calculating recombinant percent from middle gene to end gene

Answer 27

R2 + R2 + D + D / total # x 100

Question 28

do you do count doubles twice when calculating recombination frequency

Answer 28

yes

Question 29

calculating coefficient of coincidence

Answer 29

number of doubles obs / number of doubles exp

Question 30

calculating interference

Answer 30

1-coefficient of coincidence

Question 31

probability of a crossover in region 1

Answer 31

.122

Question 32

probability of a crossover in region 2

Answer 32

.146

Question 33

probability of a double crossover

Answer 33

.018

Question 34

how do you calculate the number of expected doubles

Answer 34

you multiply .018 by the total number of progeny

Question 35

what if interference is 1

Answer 35

no doubles occured

Question 36

what if interference is negative

Answer 36

more occurred than expected

Question 37

are genetic maps linear

Answer 37

yes

Question 38

are map distances additive

Answer 38

yes

Question 39

characteristics of 3 unlinked genes

Answer 39

all phenotypic classes will be equal in frequency

Question 40

characteristics of 2 linked, 1 unlinked genes

Answer 40

parentals=doubles, 2 sets of recombinants = but less than parentals and doubles

Question 41

characteristics of 3 linked genes

Answer 41

four distinct sets of phenotypic classes

Question 42

G and Q banding

Answer 42

fluoresces karyotypes to show chromosome bands

Question 43

what are the 4 chromosome aberrations

Answer 43

deletions, duplications, inversions, translocations

Question 44

what is a chromosome deletion

Answer 44

a portion of the chromosome is deleted. usually recessive lethal. can show a dominant effect.

Question 45

what is a chromosome duplication

Answer 45

a portion of the chromosome is duplicated.

Question 46

what is a chromosome inversion

Answer 46

a portion of the chromosome is flipped 180 degrees

Question 47

what is a chromosome translocation

Answer 47

a portion of the chromosome moves to a non-homologous chromosome or another place on the same chromosome

Question 48

pseudodominance

Answer 48

when a single recessive allele is inherited but still expressed

Question 49

when does the deletion loop form on chromosome deletions

Answer 49

during prophase 1

Question 50

what are polytene chromosomes

Answer 50

they remain condensed during interphase. homologous chromosomes remain paired even though there is no meiosis. they are large and easy to see.

Question 51

genetic vs cytological maps

Answer 51

co-linear but not co-metric

Question 52

cri-du-chat syndrome

Answer 52

cat-like cry, intellectually challenged, small head, small jaw, wide-set eyes

Question 53

deletions are consistently found where

Answer 53

in patients with solid tumors

Question 54

duplications in wild-type chromosomes

Answer 54

chromosomes don't align properly, so unequal crossing over

Question 55

pericentric inversion

Answer 55

includes the centromere

Question 56

paracentric inversion

Answer 56

does not include the centromere

Question 57

inversion characteristics

Answer 57

no gene imbalance, can have position effects, if moved next to heterochromatin position effects can be patchy

Question 58

dna + proteins

Answer 58

chromatin

Question 59

euchromatin

Answer 59

stains normally, thought to contain genes, loosely packed

Question 60

heterochromatin

Answer 60

densely staining, condensed chromatin thought to be genetically inert. mostly repetitive dna, tightly packed

Question 61

constitutive

Answer 61

always on

Question 62

facultative

Answer 62

occurring sometimes

Question 63

result of a crossover inside a paracentric inversion

Answer 63

gametes containing chromatin involved in crossover are non-viable. gametes containing chromatin not involved in crossover are viable.

Question 64

result of a crossover inside a pericentric inversion

Answer 64

gametes containing chromatin involved in crossover are non-viable. gametes containing chromatin not involved in crossover are viable.

Question 65

coadapted gene complex

Answer 65

a group of genetic traits with high fitness when they occur together, but without each other have low fitness

Question 66

reciprocal translocation

Answer 66

no predictable phenotypes, pairing of homozygotes is normal, pairing of heterozygotes will result in a cross shape

Question 67

how chromosomes separate in anaphase 1 - alternate segregation

Answer 67

viable gametes

Question 68

how chromosomes separate in anaphase 1 - adjacent 1 segregation

Answer 68

non-viable gametes

Question 69

how chromosomes separate in anaphase 1 - adjacent 2 segregation (rare)

Answer 69

non-viable gametes

Question 70

5:11 translocation

Answer 70

Cr- du Chat

Question 71

8:14 reciprocal translocation

Answer 71

Burkitt's lymphoma

Question 72

Reciprocal Translocations in Oenothera

Answer 72

ring chromosomes

Question 73

polyploid

Answer 73

any organism with more than 2 sets of chromosomes

Question 74

autopolyploids

Answer 74

have multiple of the species' original sets of chromosomes

Question 75

allopolyploids

Answer 75

contain sets of chromosomes from different species

Question 76

pairing possibilities in tetraploids

Answer 76

two bivalents, one quadrivalent, univalent + trivalent

Question 77

in allopolyploids who is viable

Answer 77

F1 will make non-viable progeny

Question 78

why are hybrids sterile

Answer 78

meiosis is highly unstable

Question 79

Karpechenko's Experiments

Answer 79

there can be a few fertile offspring of hybrids

Question 80

XO

Answer 80

Turner's Syndrome

Question 81

XXX

Answer 81

Trisomic X

Question 82

XXXX

Answer 82

Tetrasomic X

Question 83

XXXXX

Answer 83

Pentasomic X

Question 84

XYY

Answer 84

Jacob's Syndrome

Question 85

XXY

Answer 85

Kleinfelter's Syndome

Question 86

XXYY

Answer 86

Kleinfelter's Syndome double trisomic

Question 87

XXXY

Answer 87

Kleinfelter's Syndome tetrasomic

Question 88

2N

Answer 88

normal

Question 89

2N-1

Answer 89

monosomic

Question 90

2N-1-1

Answer 90

double monosomic

Question 91

2N-2

Answer 91

nullosomic

Question 92

2N+1

Answer 92

trisomic

Question 93

2N+1+1

Answer 93

double trisomic

Question 94

2N+2

Answer 94

tetrasomic

Question 95

Barr Body

Answer 95

condensed, inactivated X chromosome

Question 96

Barr Bodies in X0

Answer 96

0

Question 97

Barr Bodies in XX

Answer 97

1

Question 98

Barr Bodies in XXX

Answer 98

2

Question 99

Barr Bodies in XXXX

Answer 99

3

Question 100

Barr Bodies in XXXXX

Answer 100

4

Question 101

Barr Bodies in XY

Answer 101

0

Question 102

Barr Bodies in XYY

Answer 102

0

Question 103

Barr Bodies in XXY

Answer 103

1

Question 104

Barr Bodies in XXYY

Answer 104

1

Question 105

Barr Bodies in XXXY

Answer 105

2

Question 106

Barr Bodies in XXXXY

Answer 106

3

Question 107

mechanism of x-chromosome inactivation

Answer 107

repressor of inactivation binds to one x chromosome

Question 108

Down Syndrome

Answer 108

trisomic 21

Question 109

Edward Syndrome

Answer 109

trisomic 18

Question 110

Patau Syndrome

Answer 110

trisomic 13

Question 111

Warkany Syndrome

Answer 111

trisomic 8