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Chromosomes and genes > Lecture 3 and 4 > Flashcards

Lecture 3 and 4 Flashcards

1
Q

What aneuploidy occurs in down syndrome?

A

Extra chromosome 21

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2
Q

What is non-disjunction?

A

The failure of homologous chromosomes to separate properly during cell division

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3
Q

What are the 4 types of centromere position?

A

Metacentric (centre)
Submetacentric (offset from centre)
Acrocentric (severely offset)
Telocentric (at the very end)

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4
Q

What are the names given to the different length arms of a chromosome on either side of a centromere?

A 
p arm (Short)
q arm (long)
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5
Q

How long is M phase in humans?

A

2 hours

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6
Q

How long is G1 in humans?

A

11 hours

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7
Q

How long is S phase in humans?

A

7 hours

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8
Q

How long is G2 in humans?

A

4 hours

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9
Q

What are the stages of the cell cycle?

A

Prophase, metaphase, anaphase, telophase, interphase

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10
Q

What happens during prophase?

A

Chromosomes condense and thicken, appear as identical sister chromatids, mitotic spindle starts to form

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11
Q

What is the structure of the kinetochore?

A

Inner plate, middle layer, outer plate, kinetochore microtubules

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12
Q

What happens during prometaphase?

A

Nuclear envelope fragments
Centrosomes move to opposite ends
Spindle fibres attach at kinetochore

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13
Q

What happens during metaphase?

A

Sister chromatids aline along metaphase plate

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14
Q

What triggers anaphase?

A

Separase

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15
Q

How does separase trigger anaphase?

A

Hydrolyses cohesin

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16
Q

What happens during anaphase?

A

Spindle fibres contract
Pull sister chromatids apart
Daughter chromosomes at each pole

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17
Q

What happens during telophase?

A

Nuclear envelopes begin to reform, nucleoli reappear

Chromosomes decondense

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18
Q

When does cytokinesis begin?

A

Anaphase

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19
Q

When does cytokinesis end?

A

After telophase

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20
Q

How do animal cells achieve cytokinesis?

A

Contractile ring pinches cell into equal halves

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21
Q

How do plants achieve cytokinesis?

A

Membrane enclosed disk (cell plate) forms inside cell near equator

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22
Q

What is an animal cell containing two or more nuceli known as?

A

Syncytium

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23
Q

What is multinucleate plant tissue known as?

A

Coenocyte

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24
Q

What is a disadvantage of sexual reproduction?

A

Only half the genes are transmitted from each parent (less efficient to pass on genome)

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25
Q

What is oogenesis?

A

Asymmetrical meiotic division to produce one large ovum

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26
Q

What is spermatogenesis?

A

Symmetrical meiotic division to produce 4 sperm

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27
Q

When does oogenesis begin?

A

In the fetus

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28
Q

What is the first step of oogenesis?

A

Diploid germ cells, oogonia, multiply by mitosis

29
Q

What do oogonia produce?

A

Primary oocytes, which under go meiosis

30
Q

What happens when primary oocytes undergo meiosis?

A

Asymmetric division. Division is suspended at diplotene in fetus, not completed until ovulation

31
Q

What is the product of meiosis I of primary oocytes?

A 
Secondary oocyte (larger)
First polar body (smaller)
32
Q

What happens during meiosis II of the secondary oocyte?

A

Undergoes asymmetric division: haploid ovum and second polar body, then stops meiosis

33
Q

When does the meiosis II occur?

A

Fertilization

34
Q

What are male germ cells?

A

Spermatogonia

35
Q

Where does spermatogenesis occur?

A

Testes

36
Q

What does mitotic divisions of spermatogonia produce?

A

Diploid cells, primary spermatocytes

37
Q

What happens when primary spermatocytes undergo symmetrical meiotic divisions?

A

Produce secondary spermatocytes

38
Q

What happens to secondary spermatocytes at puberty?

A

Symmetrical meiosis II, produces spermatids

39
Q

What happens to spermatids?

A

Differentiate into sperm

40
Q

What are the stages of prophase I of meiosis?

A 
Leptotene
Zygotene
Pachtene
Diplotene
Diakinesis
(Loser Zoos Put Down Dogs)
41
Q

What happens during leptotene?

A

Chromosomes thicken

42
Q

What happens during zygotene?

A

Chromosomes seek homologous partners,

Synapsis

43
Q

What is the zipper that holds together homologous partners during synapsis?

A

Synaptonemal complex

44
Q

What happens during pachytene?

A

Recombination- exchange parts between non-sister chromosomes (crossing over)

45
Q

What are synapsed chromosomes known as?

A

Bivalent (two chromosomes) or tetrad (4 chromatids)

46
Q

What happens during diplotene?

A

Zipper complex dissolves

Homologous chromosomes remain merged at chiasmata

47
Q

What are chiasmata?

A

Regions where crossing-over occured

48
Q

What happens during diakinesis?

A

Further condensation

Nuclear envelope breaks down, spindle begins to from

49
Q

What happens during interkinesis of meiosis I?

A

Chromosomes decondense, sometimes stay condensed. There is no S phase.

50
Q

What happens during meisosis II?

A

Sister chromatids separate to produce haploid gametes

51
Q

At the end of meisosis II, each daughter cell has the same number of chromosomes as the parental cell. Thus meisosis is termed a _______________

A

Equational division

52
Q

When does nondisjunction occur?

A

When homologs of chromosome pairs do not segregate during meiosis I

53
Q

Who determined X and Y chromosomes determine sex?

A

Walter S. Sutton

54
Q

How did Walter S. Sutton determine X and Y chromosomes determine sex?

A

Followed meiotic divisions of cells from testes of great lubber grass hoppers- 2 chromosomes are unmatched

55
Q

What does not occur in mitosis that does in meiosis?

A

Synapsis

Crossing over

56
Q

Name 4 mistakes that can occur during cell division

A

Deletion, translocation, inversion, non-disjunction

57
Q

Name a disease associated with deletions.

A

Cri-du-chat syndrome (del(5p))

58
Q

Name a disease associated with translocation.

A

Charcot-Marie-Tooth disease type 1A (dup of portion of (p17)

59
Q

Name a disease associated with inversion.

A

(pX) implicated in mucopolysaccharidosis type II (Hunter syndrome)

60
Q

Name a disease associated with non-disjunction

A

Turner syndrome (X missing)

61
Q

What trisomy is edward syndrome?

A

18

62
Q

What trisomy is patau syndrome?

A

13

63
Q

What are some characteristics of edward syndrome?

A

Mental/physical retardation
Facial abnormalities
Extreme muscle tone
Early death

64
Q

What are some characteristics of patau syndrome?

A

Mental/physical retardation
Organ defects
Large triangular nose
Early death

65
Q

Name two ways chromosomal alterations can be diagnosed prentally.

A

Amniocentesis

Chorionic ic villi sampling

66
Q

What is amniocentesis?

A

Fetal cells are obtained from amniotic fluid

67
Q

What is chorionic villi sampling?

A

Fetal cells are obtained from the chorion (fetal part of the placenta)

68
Q

What three genetic processes can lead to genetic varation?

A

Recombination, aneuploidy, polyploidy

Chromosomes and genes (10 decks)

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