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OCR A BIOLOGY > 2.6 cell division, diversity and differentiation > Flashcards

2.6 cell division, diversity and differentiation Flashcards

1
Q

What events happen within the cell during M phase?

A
  • cell growth stops
  • mitosis
  • cytokinesis
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2
Q

What are the processes in mitosis?

A
  • prophase
  • metaphase
  • anaphase
  • telophase
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3
Q

How do cells reproduce?

A

By duplicating their contents then splitting into two identical daughter cells.

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4
Q

What is cytokinesis?

A

Cytoplasmic division following nuclear division, resulting in two new daughter cells.

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5
Q

What is interphase?

A

The phase of the cell Cycle, where the cell is not dividing, it is subdivided into growth and synthesis phases.

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6
Q

What is mitosis?

A

Type of nuclear division that produces daughter cells, genetically identical to each other and to the parent cell.

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7
Q

What are the two main checkpoints?

A
  • G1/S
  • G2/M
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8
Q

What is the purpose of checkpoints

A
  • prevent uncontrolled division, which leads to tumours.
  • to detect and repair damaged DNA.
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9
Q

Why do molecular events that control the cell cycle happen in a specific sequence?

A
  • the cycle can’t be reversed
  • DNA is only duplicated once in each cell cycle.
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10
Q

What is the hayflick constant?

A

The number of subdivisions cell can undergo. It is usually 50.

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11
Q

What is the P53 gene do?

A

Triggers the two main checkpoints in the regulation of the cell cycle.

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12
Q

What are the components of interphase.

A
  • Growth 1
  • synthesis
  • growth 2
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13
Q

What other components of m phase?

A
  • Mitosis
  • cytokinesis.
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14
Q

What is for G0 phase?

A

My cells undergo differentiation or apoptosis.

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15
Q

What is apoptosis?

A

The cell death

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16
Q

What events happen in the G0 phase?

A
  • apoptosis
  • differentiation
  • senescence
    some cells remain in this phase for a very long time or indefinitely.
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17
Q

What events happen in the G1 phase?

A
  • cells grow and increase in size.
  • Protein synthesis
  • organelles duplicate
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18
Q

What events happen in the synthesis phase?

A
  • DNA replicates
  • chromosomes have been duplicated, each pair has identical sister chromatids.
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19
Q

What happens during the G2 phase?

A

The cells grow

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20
Q

How is mitosis used?

A

FOR:
- growth—-> clonal expansion of B cells
- tissue repair
- asexual reproduction —>strawberries

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21
Q

What are chromatids?

A

Replicates of chromosomes.

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22
Q

What is tubulin?

A

cytoskeleton protein.

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23
Q

What is a centrosome?

A

A cellular structure made from two microtubule rings known as centrioles.

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24
Q

What is a chromosome?

A

Structures in a cell that contain genetic material.

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25
Q

What is a centriole?

A

A component of the cytoskeleton that is located near the nuclear envelope.

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26
Q

What is a centromere?

A

The structure in a chromosome that holds together the two chromatids.

27
Q

What is a simplified explanation of what happens during prophase?

A

Preparation for nuclear division.

28
Q

What is a simplified explanation of what happens during metaphase?

A

Middle. The chromosomes are at the equator.

29
Q

Why is it simplified explanation of what happened during anaphase?

A

Away- the chromosomes are at the poles.

30
Q

What is a simplified explanation of what happens during telophase?

A

Two nuclei - the membranes are forming.

31
Q

What are the 5 steps in prophase?

A
  1. Two identical cystic chromatids shorten and thick and into DNA supercoils.
  2. Nuclear envelope breaks down.
  3. centrioles divided into 2
  4. The two new centrioles moved to opposite poles of the cell
  5. tubulin threads form a spindle between the centrioles
32
Q

What happens during metaphase?

A
  1. Two sister chromatids
    line up around the middle of the cell
  2. Spindle threads attach to the centromere of each chromatid.
33
Q

What happens during Anaphase?

A
  1. the centromere of each pair of cystochromatids splits
  2. the spindles contract by motor proteins walking along the tubulin threads, which pull each of the sister chromatids towards opposite poles
  3. the centromeres go first, making chromatids into V shapes.
34
Q

What happens during telophase?

A
  1. the separated chromosomes reach opposite poles
  2. a new nuclear envelope forms around each set of chromosomes
  3. the cell now contains two nuclei, each genetically identical to each other and the parent cell.
35
Q

What happens after mitosis?

A

Cytokinesis.

36
Q

What happens during cytokinesis in animal cells?

A

Plasma membranes fold inwards and into the cytoplasm

37
Q

What happens during cytokinesis in plant cells?

A

An end plate forms where the spindle equator was, a new plasma membrane and cellular cell wall form either side of the plate.

38
Q

How do eukaryotic cells divide?

A

mitosis and meiosis

39
Q

How do prokaryotic cells divide?

A

binary fission

40
Q

how do viruses replicate?

A

by injecting their nucleic acid into the host cell to replicate virus particles.

41
Q

what is the longest stage of the cell cycle?

A

interphase (95%)

42
Q

what are the stages of the cell cycle?

A
  • interphase
  • nuclear division—-> mitosis, meiosis
  • cytokinesis
43
Q

what are diploid cells?

A

cells with 2 copies of each chromosome

44
Q

What does haploid mean?

A

Having only one set of chromosomes, it is represented by the symbol n.

45
Q

What homologous chromosomes?

A

Matching chromosomes contain the same genes at the same place.

46
Q

What are alleles

A

Alternative forms of a gene.

47
Q

What is meiosis?

A

a type of nuclear division that results in the formation of cells containing half the number of chromosomes of the parent cell

48
Q

What is the significance of meiosis in life cycles?

A

It increases genetic variation within a species allowing an increased chance of survival in the environment changes.

49
Q

Where is the diploid cell?

A

a cell with two sets of chromosomes represented by the symbol 2N.

50
Q

How many chromosomes do human cells have?

A

46 chromosomes
—> 23pairs.

51
Q

Why do the chromosomes only become visible in prophase?

A

Because they begin to condense.

52
Q

What are the 5 stages in meiosis?

A
  • interphase
  • meiosis 1
  • short interphase
  • meiosis 2
  • cytokinesis.
53
Q

What happens during prophase one of meiosis?

A
  • chromatin condenses so each chromosome supercoils.
  • nuclear envelope breaks down and Spindle fibres form the centriole
  • the chromosomes come together in their homologous pairs, each consisting of two chromatids.
54
Q

What happens during metaphase one with meiosis?

A
  • pairs of homologous chromosomes attach along the equator of the spindle by their centromere.
  • Homologous pairs are arranged randomly with the members of each pair facing opposite poles of the cell.
55
Q

What happens during anaphase one of meiosis?

A
  • The members of each pair of homologous chromosomes are pulled apart.
  • The centromeres do not divide
  • each chromosome consists of two chromatids - The crossover area separate from each other, resulting in swapped areas of chromosome and allele shuffling.
56
Q

What happens during telephase one of meiosis?

A
  • Two nuclear envelopes form around each set of the chromosomes in a cell divides by cytokinesis.
  • Each new nucleus contains half the original number of chromosomes, but each chromosomes consist of two chromatids.
57
Q

What happens during prophase two of meiosis?

A
  • Nuclear envelope breaks down.
  • Chromosomes coil and condense
  • the chromatids of each chromosome are no longer identical
  • Spindles form.
58
Q

What happens during metaphase two of meiosis?

A
  • Chromosomes attached by their centromere to the equator of the Spindle.
  • The chromatids are randomly arranged.
59
Q

What happens during anaphase Two of meiosis.

A
  • Centromeres divide
  • Chromatids of each chromosomes are pulled apart towards opposite poles.
60
Q

What happens during telephase two of meiosis?

A
  • nuclear envelope forms around each other for haploid nuclei.
  • The two cells now divide to give four haploid cells.
61
Q

How many haploid cells are produced in meiosis?

A

4.

62
Q

How can meiosis produce genetic variation?

A
  • The crossing over during prophase one shuffles the alleles
  • Independent assortment of chromosomes leads to further random distribution
63
Q
A

OCR A BIOLOGY (11 decks)

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