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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
What is oogenesis?
Asymmetrical meiotic division to produce one large ovum
26
What is spermatogenesis?
Symmetrical meiotic division to produce 4 sperm
27
When does oogenesis begin?
In the fetus
28
What is the first step of oogenesis?
Diploid germ cells, oogonia, multiply by mitosis
29
What do oogonia produce?
Primary oocytes, which under go meiosis
30
What happens when primary oocytes undergo meiosis?
Asymmetric division. Division is suspended at diplotene in fetus, not completed until ovulation
31
What is the product of meiosis I of primary oocytes?
``` Secondary oocyte (larger) First polar body (smaller) ```
32
What happens during meiosis II of the secondary oocyte?
Undergoes asymmetric division: haploid ovum and second polar body, then stops meiosis
33
When does the meiosis II occur?
Fertilization
34
What are male germ cells?
Spermatogonia
35
Where does spermatogenesis occur?
Testes
36
What does mitotic divisions of spermatogonia produce?
Diploid cells, primary spermatocytes
37
What happens when primary spermatocytes undergo symmetrical meiotic divisions?
Produce secondary spermatocytes
38
What happens to secondary spermatocytes at puberty?
Symmetrical meiosis II, produces spermatids
39
What happens to spermatids?
Differentiate into sperm
40
What are the stages of prophase I of meiosis?
``` Leptotene Zygotene Pachtene Diplotene Diakinesis (Loser Zoos Put Down Dogs) ```
41
What happens during leptotene?
Chromosomes thicken
42
What happens during zygotene?
Chromosomes seek homologous partners, | Synapsis
43
What is the zipper that holds together homologous partners during synapsis?
Synaptonemal complex
44
What happens during pachytene?
Recombination- exchange parts between non-sister chromosomes (crossing over)
45
What are synapsed chromosomes known as?
Bivalent (two chromosomes) or tetrad (4 chromatids)
46
What happens during diplotene?
Zipper complex dissolves | Homologous chromosomes remain merged at chiasmata
47
What are chiasmata?
Regions where crossing-over occured
48
What happens during diakinesis?
Further condensation | Nuclear envelope breaks down, spindle begins to from
49
What happens during interkinesis of meiosis I?
Chromosomes decondense, sometimes stay condensed. There is no S phase.
50
What happens during meisosis II?
Sister chromatids separate to produce haploid gametes
51
At the end of meisosis II, each daughter cell has the same number of chromosomes as the parental cell. Thus meisosis is termed a _______________
Equational division
52
When does nondisjunction occur?
When homologs of chromosome pairs do not segregate during meiosis I
53
Who determined X and Y chromosomes determine sex?
Walter S. Sutton
54
How did Walter S. Sutton determine X and Y chromosomes determine sex?
Followed meiotic divisions of cells from testes of great lubber grass hoppers- 2 chromosomes are unmatched
55
What does not occur in mitosis that does in meiosis?
Synapsis | Crossing over
56
Name 4 mistakes that can occur during cell division
Deletion, translocation, inversion, non-disjunction
57
Name a disease associated with deletions.
Cri-du-chat syndrome (del(5p))
58
Name a disease associated with translocation.
Charcot-Marie-Tooth disease type 1A (dup of portion of (p17)
59
Name a disease associated with inversion.
(pX) implicated in mucopolysaccharidosis type II (Hunter syndrome)
60
Name a disease associated with non-disjunction
Turner syndrome (X missing)
61
What trisomy is edward syndrome?
18
62
What trisomy is patau syndrome?
13
63
What are some characteristics of edward syndrome?
Mental/physical retardation Facial abnormalities Extreme muscle tone Early death
64
What are some characteristics of patau syndrome?
Mental/physical retardation Organ defects Large triangular nose Early death
65
Name two ways chromosomal alterations can be diagnosed prentally.
Amniocentesis | Chorionic ic villi sampling
66
What is amniocentesis?
Fetal cells are obtained from amniotic fluid
67
What is chorionic villi sampling?
Fetal cells are obtained from the chorion (fetal part of the placenta)
68
What three genetic processes can lead to genetic varation?
Recombination, aneuploidy, polyploidy

Chromosomes and genes (10 decks)

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