Mitosis Flashcards

1
Q

What is a centromere

A

A small section of DNA and associated proteins that attaches the sister chromatids to each other

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2
Q

What does a chromosome consist of

A
  • Replicated one = 2 chromatids each with a DNA sequence identical to the other
    • AKA sister chromatids
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3
Q

What happens to the chromatids when the centromere splits

A

Each chromatid becomes an individual chromosome

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4
Q

What are the parts of the cell cycle

A
  • Gap 1 ( G1 )
  • Synthesis ( S )
  • Gap 2 ( G2 )
  • Mitotic stage ( M )
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5
Q

Explain what happens in G1

A

This is normally the longest period of the cell cycle and stretches from the time of cytokinesis and the next round of DNA synthesis

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6
Q

Explain what happens in G2

A

This is the preparatory stage for mitosis. Organelles are replicated and proteins required in mitosis, e.g. for the formation of microtubules, are produced

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7
Q

Explain what happens in S

A

This refers to the phase in which the chromosomes are duplicated, i.e. DNA synthesis

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8
Q

Explain what happens in M

A

This involves the division of chromosomes and the subsequent cytokinesis

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9
Q

Explain G1 checkpoint

A
  • Cell cycle checkpoint
  • Apoptosis will occur is DNA is damaged and cannot be repaired
  • Otherwise the cell is committed to divide
  • Check cell and DNA for damage
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10
Q

Explain M checkpoint

A
  • Spindle assembly checkpoint
  • Mitosis will not continue if chromosomes are not properly aligned
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11
Q

Explain what needs to be ensured in the cell for DNA replication and cell division

A

No problems with cell
DNA isn’t damaged
Replicated properly

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12
Q

Explain G2 checkpoint

A
  • Mitosis checkpoint
  • Mitosis will occur if the DNA has replicated properly
    • but if there’s any problems with DNA, apoptosis will occur
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13
Q

What type of cells undergo cell division

A

Normal and undamaged cells

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14
Q

Explain mitosis fully

A
  • Main purpose of mitosis in eukaryotes is growth and the repair of damaged tissue
  • This involves the somatic cells, i.e. All cells not involved in reproduction
  • There are, however, plant, animal, fungi and prokaryotes that reproduce through mitosis and this is called asexual reproduction
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15
Q

What are daughter cells

A
  • Outcome of mitosis which are identical to parent cell ( exact same number of chromosomes as parent cell )
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16
Q

How is the number of chromosomes in daughter cell the same as in parent cell

A

Chromosome number of parent cell is duplicated before it is halved again

17
Q

What does duplication of chromosomes result in

A

2 sister chromatids held together by the centromere

18
Q

Explain early prophase

A
  • Centrosomes have duplicated
  • Chromatin is condensing into chromosomes and the nuclear envelope is fragmenting
19
Q

Explain prophase fully

A
  • Chromosomes become shorter and thicker into distinct individual chromosomes,
  • Nuclear membrane disintegrates (prometaphase), nucleolus disappears,
  • Centrioles duplicate and migrate to opposite poles and the spindle apparatus begins to form.
  • Chromosomes are seen as two sister chromatids held together at the centromere
  • Spindle fibers then attach to kinetochores - one kinetochore for each sister chromatid – complex of proteins
20
Q

Explain metaphase fully

A
  • Centromeres of duplicated chromosomes are aligned at the metaphase plate ( centre of fully formed spindle )
  • Kinetochore spindle fibres attached to the sister chromatids come from opposite spindle poles
  • The chromosomes are arranged on the equatorial plane of the spindle
21
Q

Explain anaphase

A
  • Sister chromatids part and become daughter chromosomes that move toward the spindle poles
  • Each pole receives the same number and kind of chromosomes as the parent cell
22
Q

Explain telophase

A
  • Daughter cells are forming as nuclear envelope and nucleoli reappear
  • Chromosomes will become indistinct chromatin
  • Cytokinesis takes place
  • Cleavage furrow
23
Q

Explain cytokinesis in animal cells

A
  • Cleavage furrow formed because of contractile ring
  • Division of the cytoplasm
24
Q

Explain cytokinesis in plant cells

A
  • Has a cell wall
  • Division of cytoplasm
  • Formation of cell plate which is made up of vesicles that contain cell wall components fused together