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Genetics L1 > Lecture 2 - asexual cell cycle > Flashcards

Lecture 2 - asexual cell cycle Flashcards

1
Q

What does cell division give in the asexual cell cycle?

A

identical daughter cells

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2
Q

What type of products come from asexual cell division?

A

mitotic nuclear division gives clonal products in eukaryotes

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3
Q

What does mitosis of single-celled organisms lead to?

A

clones, derived from a single ancestral cell

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4
Q

What does mitosis of multicellular organisms lead to?

A

genetically identical cells derived from a single fertilised egg

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5
Q

What are the 2 types of cells that can be found in a multicellular organism?

A

soma (body) cells
gametes (stemming from the germline)

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6
Q

What is a semidiscontinuous DNA replication?

A
  • a double-stranded chromosome which is copied to give 2 identical daughter molecules.
  • leading & lagging strand
  • complimentary DNA meaning it ends up identical
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7
Q

How do bacteria replicate?

A

binary fission

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8
Q

Describe the steps in binary fission

A
  1. DNA duplicates - cell gets bigger
  2. Replicated chromosomes move apart
  3. Protein called FtsZ marks the middle
  4. New cell wall
  5. 2 daughter cells
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9
Q

What is the structure of the cell cycle?

A

Interphase:
- G1
- S phase
- G2
Mitosis:
- PPMAT (prophase, prometaphase, metaphase, anaphase, telophase) *cytokinesis

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10
Q

In what stage of the cell cycle does the cell spend most of its time?

A

Interphase

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11
Q

What occurs during G1 phase?

A
  • cell increases in size
  • ribosomes, RNA produced
  • preparation for DNA synthesis
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12
Q

What occurs during S phase?

A
  • DNA synthesised (chromosomes duplicated)
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13
Q

What occurs during G2 phase?

A
  • cell checks fidelity (accuracy) of DNA
  • preparation for nuclear division
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14
Q

What occurs during G0 phase?

A

cell steps out of the cell cycle - inactive (quiescent) - don’t divide

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15
Q

What is the overall purpose of gap phases?

A

cell growth, protein synthesis, etc.

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16
Q

What are sister chromatids?

A

identical copied versions of chromosomes, which segregate during mitosis into new nuclei, meaning the overall amount of DNA ends up the same.

17
Q

How many sister chromatids are present between interphase & mitosis?

A

2

18
Q

What occurs during prophase?

A

chromosomes condense so they are now visible (thread-like structures), with each chromosome compromised of 2 sister chromatids and a single centromere

19
Q

What holds sister chromatids together?

A

Cohesin

19
Q

During what phase does the nuclear membrane break down?

A

prometaphase

20
Q

What is the mitotic spindle made of?

A

cytoskeleton structure - microtubules (polymers of small tubulin protein subunits)

21
Q

What is the role of the mitotic spindle?

A

to separate sister chromatids to different daughter cells

22
Q

How does the mitotic spindle separate the sister chromatids?

A

the microtubules get shorter - pulling chromosomes towards the poles

23
Q

What are centromeres?

A

specialised chromosome regions that direct the equal segregation of chromosomes during mitosis (& meiosis)

24
Q

What joins to sister chromatids together?

A

centromeres

25
Q

Where can centromeres be found?

A

at any point along the chromosome

26
Q

What connects centromeres to the microtubules?

A

a large protein complex - kinetochore

27
Q

What occurs during metaphase?

A
  • centromeres align at spindle equator (midway between the 2 poles)
  • microtubules attach to each pole - tension between these keep chromosomes in the centre
28
Q

What occurs during anaphase?

A
  • sister chromatid cohesion breaks down, separating chromatids to become separate chromosomes
  • centromeres start moving to opposite poles
  • depending on position of the centromere - each chromosome can form a V shape as it’s dragged behind the centromere
29
Q

What occurs during telophase?

A
  • chromosomes arrive at the cell poles and decondense - no longer recognisable thread structures - before the daughter nuclei then reform
30
Q

What occurs during cytokinesis?

A

division of the rest of the cell
- cleavage furrow (animals) or cell plate (plants) forms in-between the 2 poles, creating 2 daughter cells

30
Q

What is a bridge chromosome?

A

a chromosome that erroneously has 2 centromeres is pulled towards both poles at once - ends up being broken

30
Q

What are 2 examples of mitosis going wrong?

A
  • bridge chromosome
  • acentric chromosome
31
Q

What is an acentric chromosome?

A

lacking a centromere, unable to segregate properly

32
Q
A

Genetics L1 (19 decks)

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