Cell Cycle & Mitosis

Question 1

Which phase of the cell cycle does DNA replication occur?

Answer 1

interphase of the cell cycle.

Question 2

What is mitosis?

Answer 2

Mitosis is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication.

Question 3

What can uncontrolled mitosis lead to?

Answer 3

Mitosis is a controlled process.

Uncontrolled cell division can lead
to the formation of tumours and of cancers.

Question 4

What to cancer treatments target?

Answer 4

Many cancer treatments are directed at controlling the rate of cell division.

Question 5

Describe the process of binary fission.

Answer 5

• replication of the circular DNA and of plasmids
• division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids

Question 6

How do viruses replicate?

Answer 6

Being non-living, viruses do not undergo cell division.

Following injection of their nucleic acid, the infected host cell replicates the virus particles.

Question 7

How do eukaryotic cells divide?

Answer 7

Mitosis and Meiosis (gametes)

Question 8

What are the 3 stages of the cell cycle?

Answer 8

-Interphase (G1, S, G2)
-Nuclear Division (Mitosis/Meiosis)
-Cytokinesis

Question 9

Describe what each (G1, S, G2) in Interphase stands for.

Answer 9

G1- Growth - cell doubles and grows in size
S - DNA synthesis
G2 - growth and preparation for mitosis; error checking stage

(And M is mitosis in the cycle)

Question 10

Name the 4 stages of MITOSIS

Answer 10

Prophase
Metaphase
Anaphase
Telophase

Question 11

Describe Mitosis from GCSE

Answer 11

One round of division

Genetically identical cells are made

Diploid cells are made

Growth and repair- e.g. clonal expansion of B cells

Question 12

Describe Interphase

Answer 12

Interphase is the longest stage in the cell cycle.

Interphase is when the organelles double, the cell grows and then DNA replicates.

Question 13

Describe Nuclear division in cell cycle.

Answer 13

Mitosis:
-creating two identical diploid cells
-identical DNA for growth and repair

Meiosis
- creating four genetically different haploid cells.
- where as meiosis creates gametes.

Question 14

What is cytokinesis in the cell cycle?

Answer 14

Cytokinesis is the final stage.

It is the division of the cytoplasm to create the new cells.

Question 15

Describe Prophase, and how it is different in animal cells and plant cells.

Answer 15

• chromosomes condense and become visible
• Animal cells: the centrioles separate and move to opposite poles of the cell
• The centrioles are responsible for creating spindle fibres which are released from both poles to create a spindle apparatus

these will attach to the centromere and chromatids on the chromosome in later stages

• Plant cells: have a spindle apparatus, but lack the centrioles.

Question 16

Describe Metaphase in Mitosis

Answer 16

The chromosomes align along the equator of cell.

The spindle fibres released from the poles now attach to the centromere and chromatid.

[Chromosomes line up
along metaphase plate
(imaginary plane)]

Question 17

Describe Telophase & Cytokinesis

Answer 17

Telophase:

The chromosomes are now at each pole of the cell and become longer and thinner again.
The spindle fibres disintegrate, and the nucleus starts to reform.

Cytokinesis:

The final stage in the cell cycle is when the cytoplasm splits in two to create the two new genetically identical cells.

Question 18

Describe Anaphase in Mitosis

Answer 18

The spindle fibres start to retract and pull the centromere and chromatids they are bound to towards the opposite poles.

This causes the centromere to divide in two and the individual chromatids and pulled to each opposite pole.

These separated chromatids and now referred to as chromosomes.

This stage requires energy in the form of ATP which is provided by respiration in the mitochondria.