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CCEA AS Biology Units 1, 2 And 3 > (U1) Continuity Of Cells > Flashcards

(U1) Continuity Of Cells Flashcards

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1
Q

What are somatic cells?

A

Non-sex cells

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2
Q

What are gametes?

A

Sex cells

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3
Q

What are the parts of a chromosome called? (2)

A
  • chromatids
  • the centromere (centre where 2 chromatids are joined)
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4
Q

Name the stages of the cell cycle in order

A
  • mitotic (M) phase
  • G1 (gap) phase
  • S (DNA synthesis) phase
  • G2 phase
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5
Q

What does the mitotic phase consist of?

A
  • mitosis
  • then cytokinesis
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6
Q

What is mitosis? In simple terms (2)

A
  • Division of the nucleus
  • during eukaryotic cell division
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7
Q

What is cytokinesis? In simple terms (2)

A
  • division of cytoplasm
  • during eukaryotic cell division
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8
Q

What does the Synthesis phase consist of? (2)

A
  • DNA replication
  • histone production
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9
Q

What does the G1 phase consist of? (2)

A
  • synthesis of structural proteins and enzymes to perform its functions
  • organelles develop e.g. Mitochondria
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10
Q

What does the G2 phase consist of?

A

Tubulin production (protein)

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11
Q

What are the 4 stages of mitosis?

A
  • prophase
  • metaphase
  • anaphase
  • telophase
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12
Q

Outline the events of the prophase of mitosis (5)

A
  • chromatin (DNA) condenses around histones into chromosomes
  • nucleolus disintegrates
  • nuclear envelope disappears
  • centrioles migrate to opposite poles and
  • the microtubules of spindle fibres form
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13
Q

Outline the events of the metaphase of mitosis. (2)

A
  • microtubules of spindle fibres attach to the kinetochore of centromeres
  • chromosomes are lined along the equator of the cell
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14
Q

What are kinetochores? (3)

A
  • protein complexes
  • that bind to the centromeres of chromosomes
  • to allow microtubules of the spindle fibre to attach
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15
Q

Outline the events of the anaphase of mitosis. (3)

A
  • microtubules of the spindle fibres contract
  • centromere splits
  • sister chromatids are pulled to opposite poles (sides of the cell)
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16
Q

Outline the events of the telophase of mitosis. (3)

A
  • nuclear envelope reforms around each new set of chromosomes
  • chromosomes de-condense into chromatin (not visible under a light microscope)
  • microtubules of spindle fibres disperse as they are broken down
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17
Q

How does cytokinesis occur in animal cells? (5)

A
  • protein microfilaments (actin) contract along the centre of the cell
  • A cleavage furrow forms
  • as the cell surface membrane invaginates
  • eventually this spilts the cell in 2
  • leaving 2 genetically identical daughter cells
18
Q

How does cytokinesis occur in plant cells? (4)

A
  • golgi vesicles fuse to form a cell plate
  • which is laid down along the equator (centre) of the cell
  • Golgi apparatus helps synthesise materials needed to form a new cell wall
  • the cell splits in 2
19
Q

Give another name for a cell membrane

A

Cell envelope

20
Q

Put the following structures in order of origin:

  • spindle fibres
  • microtubules
  • centrioles
A
  • centrioles
  • spindle fibres
  • microtubules
21
Q

What effect does the Synthesis phase have on:

  • the amount of DNA
  • the volume of the cell
A
  • DNA doubles (due to replication)
  • volume of the cell increases slightly
22
Q

What effect does end of a cell cycle have on:

  • the amount of DNA
  • the volume of the cell
A
  • DNA halves
  • volume halves

(Nucleus splits after mitosis - cell splits after cytokinesis)

23
Q

What is the name of the 2 broad divisions in meiosis

How many phases do each contain?

A
    • Meiosis 1
    • Meiosis 2
  2. 4 each + 2 cytokinesis (10 total)
24
Q

Outline the phases of meiosis 1 and 2

A
  1. Meiosis 1:
  • prophase 1
  • metaphase 1
  • anaphase 1
  • telophase 1
  1. Cytokinesis 1
  2. Meiosis 2:
  • prophase 2
  • metaphase 2
  • anaphase 2
  • telophase 2
  1. Cytokinesis 2
25
Q

Outline prophase 1 of meiosis (6)

A
  • Chromatin becomes short and dense (forms chromosomes)
  • Homologous chromosomes form bivalents
  • Non-sister chromatids meet at chiasmata and exchange recombinant alleles – genetic crossover
  • Centrioles migrate to opposite poles
  • Microtubules develop
  • Nuclear envelope disintegrates
26
Q

Outline metaphase 1 of meiosis (2)

A
  • Bivalents attach to spindle fibres by kinetochores at centromere
  • Bivalents align at equator in a random order – independent assortment
27
Q

Outline anaphase 1 of meiosis (2)

A
  • Microtubules contract
  • Bivalents separate – whole chromosomes pulled to opposite poles – haploid no. of chromosomes formed
28
Q

Outline telophase 1 of meiosis (4)

A
  • Cluster of chromosomes go to each pole
  • Spindle disintegrates
  • 2 nuclear envelopes form – 1 for each set of chromosomes (at each pole)
  • Nucleoli reappear
29
Q

What are the only differences between meiosis 2 and meiosis 1? (4)

A
  • prophase 2: spindle fibres form at right angles to original
  • metaphase 2: individual chromosomes rather than bivalents
  • anaphase 2: non-sister chromatids pulled to opposite poles - not whole chromosomes
  • telophase 2: 2 nuclear envelopes form around each set of chromatids
30
Q

What is the purpose of checkpoints in the cell cycle? (3)

A
  • Prevents cell being the wrong size
  • Prevents DNA having errors when replicating
  • Ensures chromosomes were arranged properly in metaphase
31
Q

Where are the checkpoints in the cell cycle?

A

The end of:

  • G1
  • G2
  • Mitotic phase
32
Q

What does the G1 checkpoint check for? (4)

A
  • DNA damage
  • Cell size (i.e. organelles, macromolecules etc.)
  • Supply of nutrients (e.g. glucose)
  • Presence of growth factors
33
Q

What does the G2 checkpoint check for?

A
  • if DNA replication was done properly
  • Cell size (organelles, macromolecules etc)
34
Q

What does the mitotic checkpoint check for?

A

Number and alignment of chromosomes

35
Q

If a cell doesn’t meet the requirements of checkpoints, what happens? (3)

A
  • cell enters G0 (purgatorial phase), therefore can’t replicate
  • errors are corrected
  • cell is allowed to replicate
36
Q

How can cancer occur in the cell cycle? (2)

A
  • due to a mutation in bases in DNA – coding for wrong amino acid –> wrong protein (e.g. growth factor)
  • This can cause cells to divide uncontrollably and bypass G0
37
Q

In the cell cycle, where are cancer drugs used? (2)

A
  • synthesis phase
  • Mitotic phase
38
Q

In S phase, what types of cancer drug are used?

Describe how each work and name an example

A
  1. unzipping inhibitors:
  • inhibit enzymes like DNA Helicase so replication can’t occur
  • e.g. adriamycin and cytoxan
  1. Antimetabolites:
  • inhibit synthesis of nucleotides
  • e.g. 5-flurouracil and methotrexate
39
Q

In M phase, what type of cancer drug is used?

Describe how they work and name an example

(3)

A

Microtubule formation blockers:

  • bind to tubulin
  • chromatids can’t separate - anaphase can’t occur
  • e.g. vincristine and taxol
40
Q

How does vincristine slow down the growth of a tumour? (3)

A
  • vincristine inhibits tubulin
  • prevents microtubules being formed
  • no spindle fibre is formed

CCEA AS Biology Units 1, 2 And 3 (15 decks)

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