B9 Cell cycle Flashcards

1
Q

Describe the steps in DNA replication.

A
  • DNA helicase breaks hydrogen bonds
  • Both strands act as templates
  • Free DNA nucleotides align via complimentary base pairing
  • DNA polymerase joins nucleotides via phosphodiester bonds
    (condensation reaction)
  • New DNA double helix, one template is the original strand and one is the new strand (semi-conservative replication)
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2
Q

Describe binary fission in bacteria.

A
  • Replication of plasmids and circular DNA
  • Division of the cytoplasm to produce daughter cells
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3
Q

Describe the appearance and behaviour of chromosomes during mitosis.

A

(During prophase)
1. Chromosomes
coil / condense / shorten / thicken / become visible;
2. (Chromosomes) appear as (two sister) chromatids joined at the
centromere;
(During metaphase)
3. Chromosomes line up on the equator / centre of the cell;
4. (Chromosomes) attached to spindle fibres;
5. By their centromere;
(During anaphase)
6. The centromere splits / divides;
7. (Sister) chromatids / chromosomes are pulled to opposite poles /
ends of the cell / separate;
(During telophase)
8. Chromatids / chromosomes
uncoil / unwind / become longer / thinner.

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4
Q

What is cancer?

A
  • Cells that have damaged DNA (mutations)
  • Uncontrolled growth of cells which results in abnormal group of cells called tumours
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5
Q

What does cancer look like?

A
  • Irregular shape cell
  • Cells have more than one nucleus
  • Different antigens on their surface
  • Divide faster
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6
Q

What are the three stages of the cell cycle

A
  1. interphase
  2. Mitosis
  3. cell division (cytokinesis)
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7
Q

Describe the stages in the cell cycle.

A
  1. Interphase
    - DNA replicates and cell grows in size
    - Normal functions take place
  2. Prophase
    - DNA condenses into chromosomes
    - Nuclear membrane breaks down
    - Centrioles form spindle fibres
  3. Metaphase
    - Chromosomes line up in the centre
    - Spindle fibres attach to centromere
  4. Anaphase
    - Spindle fibres contract
    - Chromosomes split and centromeres divide
  5. Telophase
    - Nucleus reforms and chromosomes move to either ends
    - Chromosomes uncoil into DNA strands
  6. Cytokinesis
    - Cell cytoplasm and cell membrane split
    - Two genetically identical cells are formed
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8
Q

What is the definition of Oncogenes?

A

They code for proteins that stimulate division. If mutated, the proteins may over stimulate cell division

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9
Q

What is a Proto-oncogene?

A

They stimulate the cell cycle and if mutated, the cell cycle is continually active

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10
Q

What is the function of Tumour suppressor genes?

A

They code for a tumour suppressor protein which stops or slows the cell cycle, if this gene mutates it may lead to there being no way to slow mitosis, causing cance

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11
Q

What does treatment for cancer cause in the cell cycle?

A
  • ## Interfere with DNA replication and mitosis ( prevent spindle formation)
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12
Q

What normal cells are most commonly effected by chemotherapy?

A
  • Blood cells in bone marrow
  • Cells in mouth and stomach
  • Hair follicles
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13
Q

What is the reason we use acid in the required practical with garlic cloves?

A

Breaks down cell walls to get more stain in

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14
Q

Why do we stain cells in the required practical?

A

To stain the chromosomes and make them visible

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15
Q

Why do we use root tips?

A

Cells are dividing here so you will see stages of mitosis

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16
Q

Why do the cells need to be squashed?

A

To provide a single layer of cells to allow light through

17
Q

How do you work out the mitotic index?

A

number of cells in mitosis / total number of cells in view