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AQA a-level biology 🧬🔬 > DNA and cells - MITOSIS > Flashcards

DNA and cells - MITOSIS Flashcards

1
Q

What is mitosis?

A

A type of cell division

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2
Q

Name 3 uses of mitosis

A

Growth, repair and asexual reproduction

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3
Q

How many daughter cells does mitosis create?

A

2

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4
Q

How many division rounds does mitosis undergo?

A

1

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5
Q

Describe the daughter cells compared to the parent cells

A

Gentically identical, 46 chromosomes

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6
Q

What is the cell cycle?

A

The sequence of events which occurs in a cell between its formation and the time when it divides to form daughter cells

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7
Q

What happens during interphase?

A
  • Phase G1: protein synthesis; cell grows, hence volume of cytoplasm increases; more organelles produced
  • Phase S: DNA replicates
  • Phase G2: proteins needed for cell division are synthesised
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8
Q

What happens during prophase?

A
  • DNA coils and condenses
  • Sister chromatids are held together at the centromere
  • Centrioles move to opposite poles of the cell
  • Microtubules assemble around each centriole
  • Nucleolus disappears
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9
Q

What happens during metaphase?

A
  • Microtubules extend between the centrioles, forming the fibres of the nuclear spindle
  • Spindle fibres attach to the centromeres of the chromosomes
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10
Q

What is the role of spindle fibres?

A
  • Made of protein
  • Centrioles make the spindle
  • Attaches to chromosomes at centromere
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11
Q

What happens during anaphase?

A
  • Centromeres divide
  • Spindle fibres contract and pull the sister chromatids to opposite poles of the cell
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12
Q

What happens during telophase?

A
  • Nuclear membrane forms around each group of chromosomes
  • Chromosomes unwind into chromatin
  • Nucleoli form in each nucleus
  • Spindle fibres disappear
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13
Q

What happens during cytokinesis?

A
  • Cytoplasm divides to fully form 2 new cells
  • Daughter cells are genetically identical to parent cells
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14
Q

What are the two joined copies of a chromosome properly called?

A

Chromatids

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15
Q

What is the point where the two chromosome copies are joined called?

A

Centromere

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16
Q

What stage of the cell cycle involves the division of the cytoplasm?

A

Cytokinesis

17
Q

What stage of the cell cycle involves DNA replication?

A

S

18
Q

Which organisms carry out mitosis?

A

All living things

19
Q

What stage of the cell cycle involves the separation of the chromatids?

A

Anaphase

20
Q

A cell divides every one minute - At this rate of division it can fill a 100ml beaker in one hour. How much time does it take to fill a 50ml beaker? (PPQ)

A

59 minutes

21
Q

When does the nuclear envelope break down?

A

Prophase

22
Q

The chemotherapy drug cytarabine is an anti-metabolite similar to the nucleotide cytosine. The drug kills cancer cells by stopping them making and repairing DNA. At which stage in the cell cycle will cytarabine be incorporated into DNA? (PPQ)

A

S

23
Q

Where in the body do you think mitosis frequently needs cells replacing?

A
  • Skin
  • Lining of the gut
  • Red blood cells
24
Q

Give one advantage of mitosis in asexual reproduction

A

As the genetic make up of the parent has enabled it to survive and reproduce, if the offspring have the same genetic material, they are also likely to survive and reproduce

25
Q

Give one disadvantage of mitosis in asexual reproduction

A

Genetic variety is limited - if environmental conditions change the species may not have individuals with the necessary genes to survive in the new conditions, failing to adapt and becoming extinct

26
Q

How do you calculate mitotic index?

A

Mitotic index = Cells in mitosis (PMAT) / Total number of cells

27
Q

What is the mitotic index if there are 20 cells with visible chromosomes, and a further 50 cells without visible chromosomes?

A

20/75 = 0.267

28
Q

Give two processes which occur during interphase that enable cell division to occur (PPQ)

A
  • Increase in : volume of cell/volume of cytoplasm/mass/number of organelles
  • Protein synthesis
  • DNA replication
  • ATP synthesis
29
Q

Describe the appearance and behaviour of chromosomes during mitosis? (PPQ)

A

DURING PROPHASE
–>chromosomes condense and become visible
–>chromosomes appear as two sister chromatids joined by the centromere
DURING METAPHASE
–>chromosomes line up on equator
–>attached to spindle fibres by the centromere
DURING ANAPHASE
–>centromere splits
–>sister chromatids pulled to opposite poles
DURING TELOPHASE
–>chromatids uncoil

AQA a-level biology 🧬🔬 (32 decks)

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