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Molecular Test 3 > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

When is homologous recombination important?

A

Meiosis: generating diversty and chromosome segregation
Mitosis: repair DNA damage and stalled replication forks

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2
Q

What does crossing over take place between?

A

Non sister chromatids

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3
Q

Recombination

A

reassortment of genetic material already present

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4
Q

Meiotic recombination

A

aspect of sexual reproduction that can enhance genetic variability

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5
Q

Sister chromatids

A

each of 2 identical copies of a replicated chromosome. Must be linked at the centromere.

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6
Q

bivalent

A

4 chromatids

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7
Q

Diad

A

2 chromatids

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8
Q

Monad

A

one chromatid

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9
Q

First stage of prophase one

A

Leptotene

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10
Q

Leptotene

A

means thread

chromosomes become visible

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11
Q

2nd stage of prophase one

A

Zygotene

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12
Q

Zygotene

A

zygo=pair
Chromosomes pair
Synapsis occurs

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13
Q

synapsis

A

pairing of homologous chromosomes

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14
Q

3rd stage of prophase I

A

Pachytene

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15
Q

Pachytene

A

bivalents appear

Synaptonemal complex

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16
Q

Synaptonemal complex

A

forms between synapsed chromosomes and allows homologous pairing along the entire length
believed to be necessary for recombination to occur

17
Q

4th stage of prophase I

A

Diplotene

18
Q

Diplotene

A

Chiasmata form

19
Q

Chiasmata

A

sites of contact

20
Q

5th stage of prophase I

A

Diakinesis

21
Q

Terminalization

A

Chiasmata move out to the termini of chromosomes

22
Q

Axial element

A

proteinaceous structure around chromsomes that condenses at the start of synapsis

23
Q

Lateral element

A

structure in the synaptonemal complex that forms when a pair of sister chromatids condense

24
Q

Holiday Model steps

A
  1. Endonuclease nicks strand & denaturation occurs
  2. Joint molecule forms (complex strands reassociated and are sealed by ligase)
  3. Strands opposite crossover strands are nicked by endonuclease
  4. Rotation of the axis (branch migration can occur)
  5. New DNA synthesis & gaps filled
  6. Seals by ligase
  7. Have heteroduplex DNA
25
Q

Basic holliday model steps

A
  1. breakage
  2. reunion
  3. reciprocal exchange
26
Q

Branch migration

A

recombinant joint can move along the chromosome

27
Q

Topoisomerases

A

relieve tension from the twisting of DNA by breaking then remaking bond

28
Q

Type 1 topoisomerase

A

breaks single strand of DNA

29
Q

Type 2 topisomerase

A

breaks double strand of DNA

30
Q

Robertsonian fusion

A

2 acrocentric chromosomes recombine and fuse to metacentric

31
Q

Chromosome fusion

A

2 NON homologous chromosomes fuse into 1

32
Q

Chromosome fission

A

A chromosome splits into 2 chromosomes

33
Q

Where are robertsonain changes common?

A

plant and animal kingdom

Molecular Test 3 (9 decks)

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