Mitosis Flashcards

1
Q

What is mitosis?

A

The division of the cell (the nucleus), producing 2 genetically identical daughter cells

Daughter cells are identical to parent cell + contain same num of chromosomes

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2
Q

What is mitosis used for?

A
  • Growth
  • Replacement + repair of tissues in multicellular organisms
  • Asexual reproduction (in some unicellular + multicellular organisms)
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3
Q

What are examples of multicellular organisms?

A

Animals, plants, fungi

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4
Q

What are the 4 stages of mitosis?

A
  • Prophase
  • Metaphase
  • Anaphase
  • Telephase
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5
Q

How are the stages of mitosis described?

A

Distinct, but flow seamlessly from 1 to the other

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6
Q

How can each stage be identified?

A

Using a light microscope - based on characteristic features of chromosomes as they move

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7
Q

Where are dividing plant cells easily found?

A

In root tips of plants, part of meristems (actively dividing regions of plants)

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8
Q

How can the DNA within cells be seen?

A

Using staining - usually methylene blue

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9
Q

What happens in prophase (part 2)?

A
  1. 2 Centrioles migrate to opposite parts of cell
  2. Spindle fibres attack to specific parts on centromere + move chromosomes to centre of cell
  3. Nuclear envelope disappears
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10
Q

What happens in prophase (part 1 - creating chromosomes)?

A
  1. Chromatin fibres coil + condense to form chromosomes (that take up staining). Nucleolus disappears, nuclear membrane starts breaking down
  2. Protein microtubules form spindle-shaped structures, linking poles of cell
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11
Q

What happens during the metaphase?

A

Chromosomes moved by spindle fibres to form plane in centre of cell (called metaphase plate), then held in position

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12
Q

Explain the anaphase:

A
  • Centromeres holding together chromatids divide, separating them to opposite poles of cell
  • Characteristic “V” shape of chromatids moving towards poles is result of them being dragged by centromeres through liquid cytosol
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13
Q

What happens during the telophase?

A
  • Chromatids have reached poles, now called chromosomes
  • 2 new sets of chromosomes for, at each pole + nuclear envelope reforms around them
  • Chromosomes uncoil + nucleolus formed
  • Cell division/cytokinesis begins
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14
Q

What happens during cytokinesis in animal cells?

A
  • Cleavage furrow forms around middle of cell
  • Cell-surface membrane pulled inward by cytoskeleton until its close enough to fuse around middle, making 2 cells
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15
Q

Why cant a cleavage furrow be formed during cytokinesis in plant cells?

A

They have a cell wall

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16
Q

What happens during cytokinesis in plant cells?

A
  • Vesicles from golgi apparatus form in same place as metaphase plate formed
  • Vesicles move with each other + cell-surface membrane, dividing cell into 2
  • New sections of cell wall form across new sections of cell membrane
17
Q

In cytokinesis (plant cells), what happens if dividing cell wall forms before daughter cells have separated?

A

They would immediately undergo osmotic lysis from surrounding water