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Flashcards in Genetics Deck (82):
1

Whenever there's a "never" on an exam...

It's wrong

2

Medel's 2 Laws:

Segregation - gamete will have one allele or the other

Independent Assortment - alleles are mixed up

3

2 arms of a chromosome:

p - short arm

q - long arm

4

How many chromosomes in a human?

46

23 pairs

(22 pairs plus XX or XY)

5

What are the 3 positions of the Centromere:

Metacentric - in middle

Submetacentric - off center with different arm lengths

Acrocentric - centromere near top

6

What is at the end of chromosomes?

Telomeres

7

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

Sister chromatids

8

3 parts of Interphase:

G1 -

S - DNA replication (synth)

G2

9

6 phases mitosis:

Interphase (G1, S, G2)

Prophase (chromosomes condense)

Prometaphase (nuclear mem. disappears)

Metaphase

Anaphase

Telophase (cytokinesis)

10

At what point in Meiosis is there separation of centromeres?

Meiosis II

11

Describe Meiosis I:

Reduction Division

Homologues separate

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

12

Describe Meiosis II:

Sister chromatids separate

13

Where does Crossover occur in Meiosis?

Prophase I

14

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

2 parental

2 recombinant

15

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

Length

16

T/F
Decreased cross-overs are associated with increased risk of nondisjunction

True

17

What are the products of Oogenesis?

1 oocyte

2 polar bodies

*1st polar body doesn't divide again

18

4 aspects of Male Meiosis:

Puberty onset

60-65 days

4 spermatids

100-200 million/ejaculate

19

4 aspects of Female Meiosis:

3rd month embryo onset

10-50 year duration

1 ovum, 2 polar bodies

1 ovum per menstrual cycle

20

Prophase I of Meiosis (M1) 5 stages:

Leptotene - condensation

Zygotene - homologs pair

Pachytene - crossing over

Diplotene - homologs separate incompletely (still chiasma)

Diakinesis - homologs completely separate

21

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

*Homologues don't separate

2 Disomic

2 Nullisomic

*heterodisomy

22

The Disomic Gametes of M1 nondisjuction are?

Heterodisomy

23

Nondisjuction at MII will result in _____ and ______ gametes.

*homologues separate, sister chromatids don't

2 Disomic

2 Nullisomic

*isodisomy

24

The Disomic Gametes of MII nondisjunction are?

Isodisomy

25

After meiosis II, the daughter cells contain...

23 chromosomes, 23 chromatids

26

Kb =

Mb =

cM =

1% recombination =

1000 bp

1 million bp (1000 Kb)

1 Mb

1 cM

27

How do we count chromosomes?

By the number of centromeres present

28

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

46 chromosomes

29

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

92 chromatids

30

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

23 chromosomes

31

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

46 chromatids

32

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

23 chromosomes

33

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

23 chromatids

34

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

46 chromosomes

35

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

46 chromatids

36

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

46 chromosomes

37

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

92 chromatids

38

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

*immediately after mitotic division

46 chromosomes

39

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

*immediately after mitotic division

46 chromatids

40

How many chromosomes do humans have?

46 chromosomes

41

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

Metacentric

42

If the centromere is off center, the chromosome is...

Submetacentric

43

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

Acrocentric

44

P is the ____ arm

Q is the ____ arm

petite - short

long

45

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

end

middle

46

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

G1

47

DNA replication phase:

Interval between synthesis and mitosis (repair):

S

G2

48

2 aspects of Prophase:

Chromosomes condense

Mitotic spindle/centrosomes begin to form

49

What happens in Prometaphase?

Nuclear membrane disappears

50

3 aspects of Metaphase:

Chromosomes fully condense

Chromosomes line up on meta plate

Spindle fibers begin to contract

51

2 aspects of Anaphase:

Centromeres divide into 2

Spindle fibers pull chromatids apart by centromere

52

4 aspects of Telophase:

Cytokinesis

2 nuclear membranes

Spindle fibers disappear

Chromosomes revert to uncondensed form

53

Time in each:
G1

S

G2

10-12 hrs

6-8 hrs

2-4 hrs

54

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

46

92

55

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

46 chromatids

23 chromosomes

56

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

23

23

57

Sperm =

Egg =

Zygote =

23 chromosomes (23 chromatids)

23 chromosomes (23 chromatids)

46 chromosomes (46 chromatids)

58

Male gametogenesis produces:

Female gametogenesis produces:
(w/ w/out fertilization)

4 sperm cells

1 Egg, 2 Polar bodies After fertilization

1 Egg, 1 Polar body without fertilization

59

What is the average size of a gene?

Hoe many genes in the human genome?

14,000 bp (14 kb)

22,000 genes

60

cM = ____ Mb = _____ kb = ______ bp DNA

1

1000

1,000,000

61

1 cM = ___% recombination

1%

*1 million bp

62

What is at the beginning of a gene?

What sequences were previously known as junk DNA?

What are the coding sequences?

5' un-translated region

Introns

Exons

63

DNA > DNA

DNA > RNA

RNA > Protein > Translation

Replication

Transcription

Translation

64

How many codons total?

64

65

How many AA's have only 1 codon?

What are they?

2

Trp - Tryptophan - UGG

Met - Methionine - AUG - start codon

66

How many stop codons?

What are they?

3

UAA, UAG, UGA

67

Is the code the same for nucleic and mitochondrial DNA?

No.

Mitochondrial DNA uses Non-Universal codon

68

Single generation, clustered form of inheritance:

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

Autosomal recessive

2/3

69

Every generation affected, evenly distributed trait pattern:

Autosomal dominant

*Vertical Transmission

70

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

Non-penetrance of Dominant trait

71

Vertical transmission appearing out of nowhere?

New mutation - Dominant

72

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

Variable expressivity

73

Transmission that is expressed in males only?

X-linked

***female carriers

74

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

(recessive)

consanguinity

Assortative mating

Isodisomy

Lionization

Turner's syndrome

75

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

Mitochondrial

76

What are the 2 best examples of Imprinting in humans?

Prader-Willi

Angelman

77

What is the most common mechanism that causes PWS?

Minority?

Deletion of father's chromo 15 (70%)

Maternal uniparental disomy (25%)

78

What is the most common mechanism for Angelman Syndrome?

Deletion on mothers chromo 15 (70%)

79

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

Methylation Analysis

80

Uniparental Disomy has implications for what 2 types of disorders.

Recessive

Imprinted

81

6 Components of PCR:

DNA template

Primers

dNTP's

polymerase

Buffer

Mg

82

What 3 steps make up a cycle of PCR?

Denaturation

Annealing

Extension

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