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NSFC AQA A level Biology Year 1 > 3.2.2 Cell Cycle and Mitosis (Unit 2 Cells) > Flashcards

3.2.2 Cell Cycle and Mitosis (Unit 2 Cells) Flashcards

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1
Q

What are the 4 stages of mitosis?

A

Prophase

Metaphase

Anaphase

Telophase (cytokinesis)

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2
Q

What does the diagram show?

A

Anaphase

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3
Q

Cancer is caused by uncontrolled mitosis. How do most cancer drugs work?

A
  1. Preventing DNA replication/
  2. Inhibiting metaphase stage of mitosis by interfering with spindle formation.
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4
Q

What happens during prophase?

A
  • DNA condenses into chromosomes (becomes visible)
  • Centrioles move to opposite poles of cell and spindle fibres are released to form a spindle apparatus.
  • The nucleolus and nuclear envelope break down.
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5
Q

What does the diagram show?

A

Telophase (leading to cytokinesis)

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6
Q

Describe the process of bacterial binary fission

A
  • Circular DNA and plasmids replicate.
  • The cell membrane begins to grow and pinches in around the two circular DNA molecules.
  • A new cell wall forms between the two circular DNA molecules dividing the cell into 2 idenitcal daughter cells.
  • The cells have variable numbers of plasmids.
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7
Q

What does the diagram show?

A

Metaphase

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8
Q

When would mitosis not result in 2 identical daughter cells?

A

If there was a mutation (very rare)

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9
Q

Gametes (eggs and sperm) are haploid cells. What is meant by this?

A

They contain only 1 set of unparied chromosomes.

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10
Q

What is mitosis important for?

A
  • Growth
  • Replacement of damaged cells.
  • Reproduction (single celled organisms)
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11
Q

What happens during metaphase?

A

Chromosomes are positioned along equator of cell by spindle fibres.

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12
Q

What is the product of mitosis?

A

2 daughter cells that have the same number of chromosomes as the parent cell and each other.

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13
Q

What does the diagram show?

A

Prophase

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14
Q

The regular cycle of division separated by periods of cell growth is called…

A

the cell cycle

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15
Q

How much of a single cell cycle is spent in interphase?

A

approximately 90%

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16
Q

Bacterial cells replicate in a similar way to mitosis. What do we call their method of replication?

A

Binary Fission

17
Q

The rate of mitosis is controlled by…

A
  1. The environment of the cell
  2. ‘Growth factors’.
  3. Two genes.
18
Q

What happens during telophase?

A
  • Chromatids reach opposite poles.
  • Nucleas envelope and nucleolus reforms around chromosomes.
  • Spindle apparatus disintegrates.
  • Cytoplasm divides to complete cell division (cytokinesis).
19
Q

What are the 3 stages of the cell cycle?

A

Interphase

Nuclear division

Division of cyctoplasm (cytokinesis)

20
Q

How can we remember the order of the stages of mitosis?

A
  • Prophase - (Preparation - condensing and spindle formation)
  • Metaphase - (Middle - chromosomes lined up along middle of cell)
  • Anaphase - (Action - chromatids pulled apart)
  • Telophase - (Two - two new cells after division)
21
Q

How long does a mammalian cell to undergo 1 complete cell cycle?

A

24 hours

22
Q

What happens during anaphase?

A
  • Spindle fibres contract to pull sister chromatids apart at the centromere.
  • Chromatids move towards opposite poles.
23
Q

When a chromosome (DNA) replicates, the new stand is initially joined to the old at a place called the…

A

centromere.

24
Q

What are the advantages of reproducing via mitosis?

A

Only 1 parent required.

Beneficial qualities are more likely to be passed on to offspring.

25
Q

A zygote is a diploid cell. What is meant by this?

A

A cell containing 2 complete sets of chromosomes (one from each parent)

26
Q

What are the disadvantages of reproducing by mitosis?

A

Less variation in offspring.

Reduced ability to adapt to changing environment.

27
Q

What does the diagram show?

A

Interphase

28
Q

Describe a cell that is in interphase

A

Cell is actively synthesising proteins

DNA replication

Chromosomes are invisible

29
Q

why do you take cells from the root tip when studying mitosis?

A

Region where mitosis/cell division occurs;

30
Q

When when studying mitosis do you firmly squash the root tip?

A

To allow light through / make tissue layer thin;

31
Q

A cell under goes mitosis, the first division takes 24 hours and each subsequent one takes 8hours, how many cells are there after 3 days?

A

128

32
Q

How can you tell a cell has just under gone DNA replication?

A

Chromosomes are visiable as X shaped structures - 2 sister chromatids joined by a centromere

33
Q

During a root tip experiment why do we use the first 5mm of the root tip?

A

where the cells are under going mitosis

34
Q

during a root tip experiment why do we press firmly down on the cover slip?

A

make it single layer of cells SO light can pass through

35
Q

when counting cells during a root tip experiment - how can we be sure the mitotic index we calculate is accurate?

A

Look at many cells

to ensure it is representative

36
Q

when growing bacteria, equipment must be sterile before use - suggest a way of sterilising equipment and why this is important?

A

boil in water/autoclave/wash in disinfectant

to kill bateria thay may contaminate

37
Q

Describe the Cell Cycle

A

Interphase is split into G1,S and G2 phases – then the cell divides by mitosis and cytokinesis
G1 - Proteins are made, organelles are sythesised and the cell grows
S phase – DNA is replicated by semi-conservative replication
G2 – Organelles grow and divide and ATP is synthesised
Mitosis – Nuclear division
Cytokinesis – Division of the cytoplasm, two new cells are formed

38
Q

Describe how eukaryotic cells make copies of themselves

A

DNA is replicated in S-phase of interphase
Prophase – Chromosomes condense and become visible, nuclear membrane dissolves
Metaphase – Spindle fibres pull chromosomes line up at the middle of the cell
Anaphase – Sister chromatids are pulled to the opposite poles of the cell as spindle fibres contract
Telophase – Chromosomes decondense and the nuclear envelope starts to reform around the two nuclei
Cytokinesis – The cytoplasm and surface membrane splits forming two new cells that are genetically identical

NSFC AQA A level Biology Year 1 (29 decks)

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