Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BB10005 > Meiosis > Flashcards

Meiosis Flashcards

1
Q

goal of meiosis

A

Produce haploid cells with genetic material for sexual reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

diploid

A

two copies of every chromosome maternal and paternal 2n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Haploid

A

one copy of each chromosome 1n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Meiosis is

A

cell division with 2 rounds of chromosome segregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Meiosis is after

A

dna replication

2n- 4n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Meiosis 1

A

segregate homologous chromosomes

4n-2n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Meiosis 2

A

segregate sister chromatids

2n-1n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Genetic diversity in meiosis

A

Mix up paternal and maternal dna: homologous recomb
Shuffle maternal and paternal sets of chromosomes
All Mixing occurs in first round

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Mitosis review

A

See mitosis review diagram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Meosis 1 vs mitosis

A

1 vs 2 stages
Meiosis 1 is the most different from mitosis

Main difference is that in prophase there is pairing of the maternal and paternal chromsomes (homologous pair)
In anaphase these move to opposite poles of the cell

SIster chromatids (each set) have only 1 kinetochore compared to in mitosis, where they have 2

In anaphase 1 sister chromatids stay together
Instead homologous pairs move apart

Telophase 1 no cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When is homologous recomb?

A

prophase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Meiosis II

A

no further dna repl, goes straight into metaphase 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Meiosis I stages

A

interphase, prophase, metaphase 1, Anaphase 1, Telophase 1 (2 new nuclei formed- not new cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Meiosis 2 stages

A

Metaphase 2, Anaphase 2, Telophase 2, Cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Prophase I: five stages

A 
Leptotene,
 Zygotene
Pachytene
Diplotene
Diakinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Zygotene

A

Homologous chromosomes pair up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Pachytene

A

Pairing complete

Homologous chromosomes begin to exchange genetic material in homologous recomb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Diplotene

A

Pairing becomes less tight, sister chromatid pairs are visible
See evidence of crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Diplotene

A

Pairing between homo chromosomes becomes less tight, sister chromatid pairs are visible
See evidence of crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Diakinesis

A

Chromatid pairs begin to separate

nuclear envelope breaks down, spindle begins to form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Homologous chromosome pairing

A

Pair via complementary DNA sequences

Line up at the metaphase plate independently and become paired there

22
Q

What do the 2 pairs of sister chromatids form and what are they joined by

A

Form a four chromosome bivalent

Joined by synaptonemal complex (proteins)

23
Q

What is the process of pair of sister chromatids joining called

A

synapsis

- at this point the chromosome pairs can swap material

24
Q

Heteroduplexes

A

DNA double helix composed of strands that originate from 2 different duplexes (helixes)
Rapid zippering when complementary sequences meet

25
Synaptonemal complexes are tripartite
3 elements: cohesins, axial cores and transverse fibres see useful diagram chromatid-cohesin-axial core- transverse filament- axial core-cohesin- chromatid
26
How do the homologous strands find each other?
rare unless double stranded break- both threads of dna double helix severed Meiosis 1 induces programmed double strand breaks to allow homologous recomb
27
Repair of broken dna using
Homologous chromosome as a template - adv of having 2 sets of each chromosome Often occurs after dna repl in mitosis (lots of double stranded breaks) eg if something happens to maternal chromosome 2, you have paternal chromosome 2 as a template
28
Meiosis specific double strand break repair process
Nucleases induce DSBs (double strand breaks) | Favour the maternal-paternal heteroduplexes ( over normal sister chromatids eg maternal-maternal)
29
How does double strand break repair work
1. Broken end processing: - nucelases chew broken ends to leave ssDNA overhangs 2. Strand exchange: - protein complex binds the ssDNA and a double helix, which pulls it apart - if sequences match, pairing of different strands can occur see useful diagram 3. DNA synthesis to fill in gaps 4. Cut and ligate repaired strands
30
Junctions where dna crosses over each other and is cut
Holliday junction
31
Crossed over dna is in what configuration
open
32
When you cut at holiday junctions you get
crossover or conversion
33
Chiasma (crossover)
crossing, intersection | Bridges at crossover points
34
What do cells ensure with crossovers
That they don't happen too near each other | Would destabilise chromosome and incr chance of unfavourable deletion, translocation etc
35
Gene conversion
Bit of maternal strand copied into paternal, or vice versa May be some mismatched bases due to differences in DNA sequence The cell will fix this later on in its cell cycle: mismatch repair- 50 % chance of choosing either strand?
36
Metaphase 1
kinetochores in homologous pairs are monooriented - pointing in same direction
37
Prophase 1
synaptonemal complex is degraded- digest between homologous pairs Chromosomes only linked by crossover points
38
Cohesins near kinetochores protected from what in meiosis
separase which cuts through cohesins | In anaphase 1 you get cleavage of all cohesins except ones near kinetochores
39
Anaphase 1
Microtubules pull homologous pair away from each other, crossover points break
40
Metaphase II
reorientation of kinetochores: become bioriented, pointing in opposite directions Instead of being fused in a pair of chromatids, they break apart and go with the sister chromatids to each pole
41
Reorinentation of kinetochores from metaphase I to II involves
Cohesin depletion of cohesin holding chromatids together (by separase) Pulling force from microtubules in anaphase II
42
Cohesin cleavage in meiosis II
special versions of cohesin are used in meiosis- slightly different to mitosis cohesin Cohesin protected near centromere by binding to Sgo1 in meiosis 1
43
Sgo is a target of what and when
APC meiosis II to allow sister chromatids to be pulled apart
44
What is Sgo1 also involved in
sensing tension at kinetochores
45
independent assortment gives
2^n possible combos
46
Crossing over
swap large segments of homologous chromosomes- get unique combos
47
gene conversion
non-crossing over homologous recomb | Mis-match repair may copy maternal sequence into paternal chromosome, or vice versa
48
Non disjunction
chromosome segregation goes wrong | eg down syndrome
49
Spermatogenesis
formation of sperm cells | spermatogonium under goes meiosis to form 4 haploid sperm
50
oogenesis
oocyte forming egg cells one haploid egg cell formed per meiosis Half the chromosomes disposed of in polar bodies in metaphase 1 and 2 OOcyte meiosis arrests in metaphase II util fertilisation

BB10005 (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions