B2.1 Supplying the Cell - Cell cycle & Mitosis Flashcards

Mitosis, differentiation, stem cells.

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1
Q

Define Mitosis

A

A type of nuclear cell division that is used by cells for growth, repair, and healing and asexual reproduction. A stage within the cell cycle.

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2
Q

What is the cell cycle?

A
  • The process of cell growth and division for growth and repair of body cells
  • It has three main stages interphase, mitosis and cytokinesis,
  • Results in two identical daughter cells.
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3
Q

Why is interphase important?

A
  • It it the stage of growth (G1) and replication (S)
  • Before a cell can divide it needs to grow and duplicate all of its cellular contents
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4
Q

What are homologous chromosomes?

A
  • A pair of chromosomes, one from the mother, and one from the father, which are very similar to one another and have the same size and shape.
  • Most importantly, they carry the same type of genetic information: that is, they have the same genes in the same locations
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5
Q

What do the terms ‘diploid’ and ‘haploid’ mean?

A
  • Diploid = full set of chromosomes, 23 pairs/46 strands in humans
  • Haploid = half of the full set of chromosomes, 23 strands in humans
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6
Q

What is the name given to the two identical copies of each chromosome?

A

Sister chromatids

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7
Q

What is the name of the attatchment between sister chromatids?

A

Centromere.

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8
Q

What is the name given to the way in which DNA replicates?

A

Semi-conservative

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9
Q

What is meant by semi-conservative replication?

A

After replication each strand has one original strand, and one new ‘complementary’ strand

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10
Q

List the key stages in DNA replication.

A
  • Double helix untwists
  • Hydrogen bonds between bases broken, DNA ‘unzips’
  • Bases exposed on each of the two strands
  • Free nucleotides form hydrogen bonds with the exposed base (A-T, C-T)
  • Covalent bonds form between nucleotides to form ‘backbone’
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11
Q

What happens during the cell cycle after DNA replication but before mitosis?

A

The replicated DNA is checked for errors and corrections made to avoid mutations being pass on to new cells

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12
Q

Explain what happens in each of the key stages of mitosis

A
  • Prophase - Chromosomes align in the middle of the cell
  • Metaphase - Spindle fibres pull the arms of each chromosome to opposite ends of the cell.
  • Anaphase - Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells – the nucleus has divided.
  • Telophase - Cytoplasm and cell membrane divide to produce two identical daughter cells, each containing the same chromosomes.
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13
Q

What is cytokinesis?

A

The formation of the two new nuclear membrane, and pinching in of the cell membrane to separate and enclose the two new nuclei, to separate the two new cells.

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14
Q

Explain why the chromosome number must stay the same when cells divide by mitosis?

A

The chromosome number must stay the same when cells divide by mitosis to ensure the cells produced are normal body cells, identical to their parent cell.

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15
Q

When do the sister chromatids condense>

A

During prophase the sister chromatids condense to form x-shaped chromosomes linked by a centromere.

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16
Q

What is the longest stage of the cell cycle called?

A

Interphase

17
Q

During what stage does the G1, S, and G2 phases happen?

A

Interphase

18
Q

Where in a plant does mitosis take place?

A

The tips of roots and shoots

19
Q

How can mitosis be easily observed in a school laboratory?

A

Be preparing a ‘root squash’.

20
Q

What is a root tip squash?

A

A method of preparing root tip meristem cells to observe them using a light microscope at different stages of the cell cycle