Mitosis

Question 1

In which type of cells does mitosis occur?

Answer 1

Eukaryotes

Question 2

What’s the outcome of mitosis?

Answer 2

A parent cell divides to form 2 genetically identical daughter cells (containing an exact copy of DNA).

Question 3

When is mitosis needed?

Answer 3

Fr the growth of multicellular organisms (eg humans) and for repairing damaged tissues.

Question 4

What is interphase?

Answer 4

G1 + S + G2

Question 5

What happens in G1?

Answer 5

The cell carries out its normal activities.
New organelles produced.

DNA content: 20 arbitrary

Question 6

What happens in S?

Answer 6

Cell replicates its DNA, ready to divide by mitosis.
Checked for errors.

DNA content: 40 arbitary.

Question 7

What happens in G2?

Answer 7

Cell continues growing.
Cytoskeleton of cell breaks down and all of the protein microtubule components begin to reassemble into spindle fibres.

DNA content: 40 arbitrary.

Question 8

What are the stages is mitosis?

Answer 8

Prophase, Metaphase, Anaphase, Telophase

PMAT

Question 9

What happens in prophase?

Answer 9

• chromosomes first become visible, they condense; getting shorter and fatter.
• chromosomes move to poles of cell.
• from each of the centrioles, spindle fibres develop, which span the cell pole to pole
• nucleolus disappears
• nuclear envelope breaks down, leaving the chromosomes free in the cytoplasm

Question 10

What happens in metaphase?

Answer 10

• chromosomes seen to be made up of 2 chromatids
• chromatids are joined by the centromere
• the spindle fibres are pulled along by the spindle apparatus and arrange themselves across the equator of the cell

Question 11

What happens in anaphase?

Answer 11

• centromeres divides into 2, separating each pair of sister chromosomes
• spindles contract, pulling chromatids to opposite poles of the spindle which make chromatids appear V-shaped
• energy for this is provided by the mitochondria, which gather around the spindle fibres

Question 12

What happens in telophase?

Answer 12

• chromatids reach the opposite poles on the spindle
• chromatids become longer and thinner and are new chromes again
• nuclear envelope forms around each group of chromosomes
• spindle fibres disintegrate
• nucleolus re-forms
• cytoplasm divides (cytokinesis) and there are now 2 daughter cells which are genetically identical to the original cell and each other.

Question 13

How does cell division by non prokaryotes take place?

Answer 13

By binary fission