12 - The Cell Cycle and Cell Division (C2) Flashcards

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1
Q

What is the name of the region where chromatids join?

A

Centromere

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2
Q

What does haploid mean?

A

Having 1 complete set of chromosomes

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3
Q

What does diploid mean?

A

Having 2 complete sets of chromosomes

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4
Q

What is cytokinesis?

A

The division of the cytoplasm to form 2 daughter cells

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5
Q

What is the difference between interphase in meiosis 1 and 2?

A

In meiosis 2 DNA doesn’t replicate

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6
Q

What happens during interphase of mitosis / meiosis 1?

A
  • DNA replicates
  • Cell organelles duplicate
  • Cell builds the proteins needed for division
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7
Q

Why are interphase and cytokinesis not considered as part of mitosis / meiosis 1?

A

Because the chromosomes aren’t visible

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8
Q

What happens in prophase of mitosis?

A
  • Chromosomes condense and appear as ‘X’ shaped structures
  • Centrioles move to poles
  • Spindle fibres start to develop
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9
Q

What is the order of stages in mitosis and meiosis?

A
  • Interphase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
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10
Q

What happens in metaphase of mitosis?

A
  • Chromosomes move to and line up on equator

- Spindle fibres connect between centriole and centromea

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11
Q

What happens in anaphase of mitosis?

A
  • Spindle fibres shorten
  • 1 chromatid is pulled from each chromosome to each pole
  • Separating the centromea
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12
Q

What happens in telophase of mitosis?

A
  • Chromosomes uncoil (decondense)
  • Spindle fibres break down
  • Endo-membranes reform
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13
Q

When does prophase occur in mitosis?

A

As soon as chromosomes become visible

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14
Q

When does metaphase occur in mitosis?

A

As soon as nuclear envelope breaks down

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15
Q

When does anaphase occur in mitosis?

A

As soon as chromatids start to separate

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16
Q

When does telophase occur in mitosis?

A

As soon as chromatids reach the poles

17
Q

What happens in prophase of meiosis 1 / 2?

A
  • Chromosomes condense and line up in their homologous pairs
  • Chromatids cross over and exchange genetic information between homologous pairs
  • Centrioles move to poles and spindle fibres appear
18
Q

What happens in metaphase of meiosis 1 / 2?

A
  • Chromosomes move to and line up in their pairs on the equator
  • Spindle fibres connect between centromeas and centrioles
19
Q

What happens in anaphase of meiosis 1 / 2?

A
  • Spindle fibres shorten
  • 1 chromosome from each pair is pulled to each pole
  • Centromeas don’t separate
20
Q

What happens in telophase of meiosis 1 / 2?

A

Usually:

  • Chromosomes uncoil
  • Endomembranes reform
  • Spindle fibres break down
21
Q

Why does mitosis happen?

A

To produce genetically identical cells for growth and repair, and asexual reproduction

22
Q

Why does meiosis happen?

A

To produce cells with half the number of chromosomes which are gametes for sexual reproduction

23
Q

What causes independent assortment?

A

The random orientation of chromosomes pairs at metaphase 1 and of chromatids at metaphase 2

24
Q

What causes recombination due to crossover?

A
  • Homologous chromosomes cross over during prophase 1. Their chromatids form chiasmata which move towards the ends leading to the exchange of genes
  • If 2 genes are on the same chromosome some gametes will inherit the parental combinations, whilst others will be recombinant
25
Q

What causes chromosome mutation, leading to Polysomy (Down’s syndrome) or Polyploidy?

A

Unequal separation of chromosomes at anaphase 1 or 2

26
Q

What causes chromosome mutation, leading to duplication or inversion?

A

A failure of DNA being exchanged equally during cross over at prophase 1

27
Q

What causes point mutation during meiosis?

A

Mistake in DNA replication (base pairing) during interphase

28
Q

What happens in phase M?

A
  • DNA is condensed and splits

- 4 phases: prophase, metaphase, anaphase, telophase

29
Q

What happens in phase G1?

A

Cell grows and develops into a mature cell

30
Q

What happens in phase S?

A

The cell duplicates the DNA and centromere

31
Q

What happens in phase G2?

A

The cell prepares for mitosis. It’s still growing and making proteins and organelles

32
Q

What are G1, S and G2 collectively called?

A

Interphase

33
Q

What are differences between mitosis in animal cells and plant cells?

A

ANIMAL

  • Cell becomes rounded before mitosis
  • Centrioles present
  • Cleavage furrow, which develops from outside inwards
  • Spindle fibres degenerate at telophase
  • Occurs in epithelia, bone marrow etc

PLANT

  • No shape change
  • Centrioles absent
  • Cell plate, which develops from centre outwards
  • Spindle fibres remain throughout new cell wall formation
  • Occurs in meristems
34
Q

How is prophase 2 different to prophase 1?

A

At prophase 2 the centrioles separate and organise a new spindle at right angles to the old spindle