Cell cycle, Mitosis and Meiosis Flashcards

1
Q

What happens during G1

A

Protein synthesis
Replication of organelles
cell increases in size

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2
Q

What happens during S

A

Chromosomes are duplicated / DNA is replicated

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3
Q

What happens during G2

A

Increase in cell size
increase in energy stores
Duplicated DNA from S phase is checked for errors

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4
Q

What is G0

A

When the cell leaves the cell cycle permanently or temporarily.

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5
Q

Why would the cell leave the cycle?

A

DNA may be damaged - The cell should no longer divided, so the cell enters a state of arrest.

Age - As you get older you have more cells, therefore by leaving the cycle they can’t replicate, this decreases the chances of problems such as arthritis

Differentiation - Once a cell has specialised it may no longer divided and re-enter the cell cycle.

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6
Q

What is the G1 checkpoint

A

Makes sure the cell is the correct size
Makes sure the cell has the correct nutrients
Checks DNA for damage before entering S phase

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7
Q

What is the G2 checkpoint

A

Makes sure the cell is the correct size

Checks if the replicated DNA has any errors after S phase

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8
Q

What is the spindle assembly checkpoint

A

Checks the spindle fibres are connected to the chromosomes

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9
Q

Uses of mitosis

A

Asexual reproduction
Growth of Multicellular organisms
Tissue repair

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10
Q

What does it produce?

A

Two identical daughter cells

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11
Q

What occurs during S phase (mitosis)

A

The chromatids are. separated via the centromere they must stay together so each can go into a daughter cell

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12
Q

Acronym for the stages of mitosis

A

People (Prophase)
Must (Metapahse)
Attack (Anaphase)
Teachers (Telophase)

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13
Q

What happens during Prophase of mitosis

A
  1. Chromatin begins to coil and condenses to form chromosomes and become visible under the microscope
  2. The nuclear membrane breaks down
  3. Microtubules form spindle fibers
  4. Centrioles move to opposite ends of the poles
  5. Spindle fibres connect to the centromeres of the chromatins
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14
Q

What happens during Metaphase of mitosis

A

Chromosomes are pulled to the centre of the cell to form a line called the Metaphase plane where is stays until Anaphase

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15
Q

What happens during Anaphase of mitosis

A

The centromeres holding the chromatids together pull the chromatids to opposite sides of the cell. They form a ‘V’ like shape making the easily identifiable

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16
Q

What happens during Telophase of mitosis

A
  1. The two new set of chromosomes assemble at the end of each pole, and a nuclear envelope forms around them.
  2. The chromosomes uncoil and a nucleolus forms
  3. Cytokinesis begins
17
Q

What is cytokinesis

A

The actual split off the cell.

18
Q

What happens in animal cells during cytokinesis

A
  1. A cleavage forms at the centre of the cell.

2. The cell surface membrane is pulled inwards by. the cytoskeleton until it fuses in the middle forming two cells.

19
Q

What happens in Plant cells during cytokinesis

A
  1. Vesicles from ht Golgi form where. the metaphase plate was.
  2. The vesicles eventually fuse together.
  3. A new cell wall is formed essentially making a new cell.
20
Q

How many chromosomes are present during mitosis

A

There are 46 chromosomes throughout however during prophase there are 96 chromatids.

21
Q

Uses of meiosis

A

The formation of gametes / sex cells

22
Q

What is a homologous chromosome

A

A matching pare of chromosomes, one inherited from each parent.

23
Q

What does diploid mean

A

The normal number of chromosomes (46)

24
Q

What does haploid mean

A

Half the number of normal chromosomes (23)

25
What is Meiosis 1
The first division = reduction division | Homologous chromosomes go into two cells
26
What is Meiosis 2
Secondary division = similar mitosis | Everything is halved again
27
What happens during Prophase 1 of meiosis and what is the difference
Chromosomes condense Nuclear envelope dissolves Nucleolus disappears Spindle begins to form Difference: Homologous chromosomes pair up forming bivalent, when the chromosomes flow through their liquid they entangle.
28
What happens during Metaphase 1 of meiosis and what is the difference
Chromosomes are pulled to the middle the cell and form along the metaphase plate Differences: Homologous chromosomes form up against. the metaphase line instead of individual chromosomes. The position of the chromosomes are random, this is called independent assortment.
29
What happens during Anaphase 1 of meiosis
The homologous chromosomes are separated and are pulled to the opposite poles via spindle fibres The bivalent entangled chromosomes are pulled. apart. and re join at the chiasma, this is an exchange of DNA
30
What happens during Telophase 1 of meiosis
Chromosomes assemble together Nuclear membrane form around them The chromosomes uncoil. Cytokinesis occurs
31
What happens during Prophase 2 of meiosis
Chromosomes condense Nuclear membrane breaks down Spindle fibres form
32
What happens during Metaphase 2 of meiosis
Individual chromosomes area aligned along the metaphase plate like in mitosis
33
What happens during Anaphase 2 of meiosis
The individual chromosomes are pulled to opposite ends of the poles.
34
What happens during telophase 2 of meiosis
Nuclear membrane forms around the chromosomes Chromosomes uncoil and nucleolus forms Cytokinesis coccus forming 4 genetically different daughter cells.