Mitosis (and binary fission) 3.2.2

Question 1

How many daughter cells are created with mitosis

Answer 1

2

Question 2

How does the genetic information compare to the parent cell

Answer 2

It is an exact copy

Question 3

How is cytokinesis proceeded

Answer 3

By interphase

Question 4

What are the three stages of interphase

Answer 4

G1. growth, new organelles formed, proteins synthesised
S. DNA replication - DNA is doubled
G2. growth and proteins synthesised

Question 5

What are the stages of mitosis

Answer 5

Prophase
Metaphase
Anaphase
Telophase

Question 6

Describe the stage of prophase

Answer 6

Chromosomes become visible, they shorten and thicken
Centrioles moved to opposite poles of the cell
Spindle fibres develop, which is banned from pole to pole (collectively known as spindle apparatus)
Nucleolus disappears and the nuclear envelope breaks down, leaving the chromosomes free in the cytoplasm of the cell

Question 7

Describe the stage of metaphase

Answer 7

Chromosomes are seen to be made up of two chromatids. Each chromatid is an identical copy of DNA from the parent cell. The chromatids are joined together by the centromere. It is to this centromere that some microtubules from the poles are attached, and the chromosomes are pulled along to spindle apparatus and the range themselves across the equator of the cell

Question 8

Describe the stage of anaphase

Answer 8

The centromere is divided to 2 and the spindle fibres pull the individual chromatids making up the chromosome apart. Chromatids move rapidly to their respective, opposite poles of the cell and we now refer to them as chromosomes. The energy for the process is provided by mitochondria, which gather around the spindle fibres. If the cell is treated with chemicals that destroy the spindle, the chromosomes remain at equator, unable to reach the poles.

Question 9

Describe Telophase

Answer 9

The chromosomes reach their respective polls and become longer and thinner, finally disappearing altogether, leaving only widely spread chromatin. The spindle fibres disintegrate and the nuclear envelope and nucleolus reform.

Question 10

Describe cytokinesis

Answer 10

The dividing of the cytoplasm

Question 11

Where does mitosis occur in plants

Answer 11

In meristematic cells

Question 12

Differences of mitosis in plants

Answer 12

• During prophase the spindle forms without centrioles
• Cytokinesis begins at the centre of a cell with the seller plate. This is a double membrane which secretes materials needed to make to sell walls. The cell walls begin to form in the centre and the outwards until they meet the perimeter.

Question 13

Describe binary fission

Answer 13

• The circular DNA molecule replicates and both copies attach to the cell membrane.
• The plasmids also replicate.
• The cell membrane begins to grow between the two DNA molecules and begin to pinch inward, dividing the cytoplasm into two.
• A new cell wall forms between the two molecules of DNA, dividing the original into two identical daughter cells, each with a single copy of circular DNA and a variable number of copies of the plasmids.

Question 14

How do viruses replicate

Answer 14

Viruses are nonliving they can’t go under cell division.

They replicate by attaching themselves to their host cell with the attachment proteins on their surface.
They then inject their nucleic acid into the host cell. The genetic information on the injected viral nucleic acid then provides the instructions for the host cells metabolic processes to start producing the viral components, nucleic acids, enzymes and structural proteins which are then assembled into new viruses