Genetics Flashcards

1
Q

Whenever there’s a “never” on an exam…

A

It’s wrong

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2
Q

Medel’s 2 Laws:

A

Segregation - gamete will have one allele or the other

Independent Assortment - alleles are mixed up

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3
Q

2 arms of a chromosome:

A

p - short arm

q - long arm

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4
Q

How many chromosomes in a human?

A

46

23 pairs

(22 pairs plus XX or XY)

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5
Q

What are the 3 positions of the Centromere:

A

Metacentric - in middle

Submetacentric - off center with different arm lengths

Acrocentric - centromere near top

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6
Q

What is at the end of chromosomes?

A

Telomeres

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7
Q

What are 2 arms of a replicated chromosome held together at a centromere?

A

Sister chromatids

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8
Q

3 parts of Interphase:

A

G1 -

S - DNA replication (synth)

G2

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9
Q

6 phases mitosis:

A

Interphase (G1, S, G2)

Prophase (chromosomes condense)

Prometaphase (nuclear mem. disappears)

Metaphase

Anaphase

Telophase (cytokinesis)

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10
Q

At what point in Meiosis is there separation of centromeres?

A

Meiosis II

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11
Q

Describe Meiosis I:

A

Reduction Division

Homologues separate

46 > 23 / (2n > 1n) / diploid > haploid

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12
Q

Describe Meiosis II:

A

Sister chromatids separate

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13
Q

Where does Crossover occur in Meiosis?

A

Prophase I

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14
Q

In recombination, homologous chromosomes line up and crossover, producing ______ and _____ gametes

A

2 parental

2 recombinant

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15
Q

The number of cross-over events is related to the _____ of the chromosome arm.

A

Length

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16
Q

T/F

Decreased cross-overs are associated with increased risk of nondisjunction

A

True

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17
Q

What are the products of Oogenesis?

A

1 oocyte

2 polar bodies

*1st polar body doesn’t divide again

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18
Q

4 aspects of Male Meiosis:

A

Puberty onset

60-65 days

4 spermatids

100-200 million/ejaculate

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19
Q

4 aspects of Female Meiosis:

A

3rd month embryo onset

10-50 year duration

1 ovum, 2 polar bodies

1 ovum per menstrual cycle

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20
Q

Prophase I of Meiosis (M1) 5 stages:

A

Leptotene - condensation

Zygotene - homologs pair

Pachytene - crossing over

Diplotene - homologs separate incompletely (still chiasma)

Diakinesis - homologs completely separate

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21
Q

Nondisjuction at M1 (prophase I) will result in _____ and _____ gametes.

*Homologues don’t separate

A

2 Disomic

2 Nullisomic

*heterodisomy

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22
Q

The Disomic Gametes of M1 nondisjuction are?

A

Heterodisomy

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23
Q

Nondisjuction at MII will result in _____ and ______ gametes.

*homologues separate, sister chromatids don’t

A

2 Disomic

2 Nullisomic

*isodisomy

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24
Q

The Disomic Gametes of MII nondisjunction are?

A

Isodisomy

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25
Q

After meiosis II, the daughter cells contain…

A

23 chromosomes, 23 chromatids

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26
Q

Kb =

Mb =

cM =

1% recombination =

A

1000 bp

1 million bp (1000 Kb)

1 Mb

1 cM

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27
Q

How do we count chromosomes?

A

By the number of centromeres present

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28
Q

At the beginning of Meiosis I, how many Chromosomes does the cell contain?

A

46 chromosomes

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29
Q

At the beginning of M1, how many Chromatids does the cell contain?

A

92 chromatids

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30
Q

At the end of M1, how many Chromosomes does the cell contain?

A

23 chromosomes

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31
Q

At the end of M1, how many Chromatids does the cell contain?

A

46 chromatids

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32
Q

At the end of Meiosis II, how many chromosomes does the cell contain?

A

23 chromosomes

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33
Q

At the end of MII, how many Chromatids does the cell contain?

A

23 chromatids

34
Q

Immediately after fertilization, how many chromosomes does the zygote contain?

A

46 chromosomes

35
Q

Immediately after fertilization, how many Chromatids does the zygote contain?

A

46 chromatids

36
Q

The zygote prepares to divide. Immediately before the first mitotic division, the cell contains how many Chromosomes?

A

46 chromosomes

37
Q

The zygote prepares to divide. Immediately before the first mitotic division, the cell contains how many Chromatids?

A

92 chromatids

38
Q

In a 2 cell embryo, how many Chromosomes are in each cell?

*immediately after mitotic division

A

46 chromosomes

39
Q

In a 2 cell embryo, how many Chromatids are in each cell?

*immediately after mitotic division

A

46 chromatids

40
Q

How many chromosomes do humans have?

A

46 chromosomes

41
Q

If short arms and large arms are about the same length and the centromere is in the middle, the chromosome is said to be…

A

Metacentric

42
Q

If the centromere is off center, the chromosome is…

A

Submetacentric

43
Q

If the centromere is extremely off center, the chromosome is…

A

Acrocentric

44
Q

P is the ____ arm

Q is the ____ arm

A

petite - short

long

45
Q

Telomeres are at the _____, centromeres are in the ____.

A

end

middle

46
Q

What is the Growth stage between mitosis and replication (preparing to replicate)?

A

G1

47
Q

DNA replication phase:

Interval between synthesis and mitosis (repair):

A

S

G2

48
Q

2 aspects of Prophase:

A

Chromosomes condense

Mitotic spindle/centrosomes begin to form

49
Q

What happens in Prometaphase?

A

Nuclear membrane disappears

50
Q

3 aspects of Metaphase:

A

Chromosomes fully condense

Chromosomes line up on meta plate

Spindle fibers begin to contract

51
Q

2 aspects of Anaphase:

A

Centromeres divide into 2

Spindle fibers pull chromatids apart by centromere

52
Q

4 aspects of Telophase:

A

Cytokinesis

2 nuclear membranes

Spindle fibers disappear

Chromosomes revert to uncondensed form

53
Q

Time in each:
G1

S

G2

A

10-12 hrs

6-8 hrs

2-4 hrs

54
Q

At the beginning of M1, a human cell contains ______ chromosomes and ______ chromatids.

A

46

92

55
Q

In M2, 2 cells have _____ chromatids each containing _______ chromosomes

A

46 chromatids

23 chromosomes

56
Q

At the end of M2, 4 cells have ___ chromosomes and __ chromatids.

A

23

23

57
Q

Sperm =

Egg =

Zygote =

A

23 chromosomes (23 chromatids)

23 chromosomes (23 chromatids)

46 chromosomes (46 chromatids)

58
Q

Male gametogenesis produces:

Female gametogenesis produces:
w/ w/out fertilization

A

4 sperm cells

1 Egg, 2 Polar bodies After fertilization

1 Egg, 1 Polar body without fertilization

59
Q

What is the average size of a gene?

Hoe many genes in the human genome?

A

14,000 bp (14 kb)

22,000 genes

60
Q

cM = ____ Mb = _____ kb = ______ bp DNA

A

1

1000

1,000,000

61
Q

1 cM = ___% recombination

A

1%

*1 million bp

62
Q

What is at the beginning of a gene?

What sequences were previously known as junk DNA?

What are the coding sequences?

A

5’ un-translated region

Introns

Exons

63
Q

DNA > DNA

DNA > RNA

RNA > Protein > Translation

A

Replication

Transcription

Translation

64
Q

How many codons total?

A

64

65
Q

How many AA’s have only 1 codon?

What are they?

A

2

Trp - Tryptophan - UGG

Met - Methionine - AUG - start codon

66
Q

How many stop codons?

What are they?

A

3

UAA, UAG, UGA

67
Q

Is the code the same for nucleic and mitochondrial DNA?

A

No.

Mitochondrial DNA uses Non-Universal codon

68
Q

Single generation, clustered form of inheritance:

If sister expresses an Autosomal Recessive disorder, the chances of being a carrier are:

A

Autosomal recessive

2/3

69
Q

Every generation affected, evenly distributed trait pattern:

A

Autosomal dominant

*Vertical Transmission

70
Q

What inheritance pattern looks like vertical recessive because it skips generations?

A

Non-penetrance of Dominant trait

71
Q

Vertical transmission appearing out of nowhere?

A

New mutation - Dominant

72
Q

A genetic disease that can be mild in one pt and severe in another may be exhibiting what?

A

Variable expressivity

73
Q

Transmission that is expressed in males only?

A

X-linked

***female carriers

74
Q

5 ways a female can have an X-linked disorder:

recessive

A

consanguinity

Assortative mating

Isodisomy

Lionization

Turner’s syndrome

75
Q

If mother passes trait on to all, and sons don’t pass but daughters do…

A

Mitochondrial

76
Q

What are the 2 best examples of Imprinting in humans?

A

Prader-Willi

Angelman

77
Q

What is the most common mechanism that causes PWS?

Minority?

A

Deletion of father’s chromo 15 (70%)

Maternal uniparental disomy (25%)

78
Q

What is the most common mechanism for Angelman Syndrome?

A

Deletion on mothers chromo 15 (70%)

79
Q

______ is the most efficient way to test PWS and AS.

A

Methylation Analysis

80
Q

Uniparental Disomy has implications for what 2 types of disorders.

A

Recessive

Imprinted

81
Q

6 Components of PCR:

A

DNA template

Primers

dNTP’s

polymerase

Buffer

Mg

82
Q

What 3 steps make up a cycle of PCR?

A

Denaturation

Annealing

Extension