3) The Cell Cycle

Question 1

what is the purpose of cell division

Answer 1

growth and repair

Question 2

why is important that the daughter cell produced are genetically identical

Answer 2

so there is no loss of genetic information

Question 3

what circumstances would the daughter cell not be genetically identical

Answer 3

when there us a mistake in the genetic material

Question 4

describe cell division in prokaryotic cells

Answer 4

• replication of circular chromosome
• cell growth
• ingrowth of plasma membrane and cell wall
• cell divides

Question 5

why do multicellular eukaryotes need to be able to control the rate of their cell cycle

Answer 5

• to avoid over production of cells, leading to tumours

* to avoid under production of cells, leading to degenerative disease like alzheimers

Question 6

Name and describe the 2 phases the cell cycle in eukaryotes

Answer 6

Interphase - period of cell growth and DNA replication

M phase - segregation of replicated chromosomes and division of cytoplasm to form two genetically identical cells

Question 7

Name and describe the 3 parts of INTERPHASE

Answer 7

G1 - cell growth
S - replication of DNA
G2 - cell growth

Question 8

Name and describe the 2 process that occur in M phase

Answer 8

Mitosis - separation of chromosomes and the formation of daughter nuclei

Cytokinesis - separation of cytoplasm into two daughter cells

Question 9

Name the 4 stages of mitosis

Answer 9

Prophase
Metaphase
Anaphase
Telophase

Question 10

Put these in order:

Metaphase, Telopahse, prophase, anaphase

Answer 10

Prophase
Metaphase
Anaphase
Telophase

Question 11

What happens in the:

prophase

Answer 11

• compacting of chromotin to chromotids

* put chromotids in pairs and holding them together by ‘glue’

Question 12

what happens in the:

metaphase

Answer 12

•chromosones are in the middle and spindle fibres become attached to each chromotid

Question 13

what happens in the:

anaphase

Answer 13

• division of chromsomes, as the protein holding them together is degraded
• the spindle fibres attached to each daughter chromosome shorten and pull them to opposite ends of the pole

Question 14

what happens in the:

telophase

Answer 14

• daughter chromosomes arrive at the poles and unravel

* a nuclear envelope assemble round each group creating daughter nuclei.

Question 15

how do you calculate the mitotic index

Answer 15

number of cells undergoing mitosis/total number of cells *100

Question 16

describe the process of cytokinesis in animals

Answer 16

• the cytoskeleton contracts from the inside and pinches itself together
• when they meet they are cleaved and the cell separates