cell cycle

Question 1

name and summarise the 3 phases of cell cycle

Answer 1

Interphase – takes up majority of the time (12-24hrs to complete)
- Growth and development of cell
- prepare for reproduction-DNA synthesis, etc.

Mitotic Phase = division of nucleus and cell
- 4 phases involved

Cytokinesis (final phase)= division of cell – where newly produced daughter cells physically separate and new membranes form around the 2 cells

Question 2

which type of cells mainly undertake cell cycle

Answer 2

eukaryotic cells

Question 3

what is the cell cycle

Answer 3

n ordered series of events where the cell duplicates its condense and duplicates into 2 new cells

Question 4

how is fidelity of multicellular organism maintained in this process

Answer 4

by highly ordered and tightly regulated process

Question 5

in interphase what is between the G phases

Answer 5

the S (synthetic) phase and that’s where chromosomes duplicate

Question 6

what is the first stage of mitosis and explain

Answer 6

is prophase.
This can be separated into early and late stages and is where duplicated chromosomes condense and outside the nucleus the mitotic spindle starts to assemble

Centrosomes hold onto the mitotic spindle. Centrosome is an organelle, that serves as a microtubule organising centre, and are involved in attachment to the sister chromatids. Which is seen in late prophase

Question 7

explain the Prophase/Prometaphase

Answer 7

• Centrioles move to opposite ends
• Nuclear envelope disappears
• Chromosomes appear with centromeres
• Chromosomes move to spindles

So we see the movement of sister chromatids so they can be divided and taken to poles of the cell so new cells can be produced

Question 8

describe metaphase

Answer 8

Chromosomes lined up in centre, On the Metaphase plate

spindles attached to the sister chromatids, which are connected to the centrosomes at the opposite poles of the spindles.

Question 9

describe anaphase

Answer 9

Sister chromosomes move to opposite ends of spindle, to form the 2 new sets of daughter chromatids

The cell elongates and cleavage furrow forms in late anaphase. Helping to facilitate the separation of the 2 new daughter cells during the last phase of mitosis.

Question 10

describe telophase

Answer 10

• Nuclear envelopes reappear
• Cytokinesis is completed

This is the last phase

At telophase, the cell continues to elongate as free spindle fibres from each centrosome push off each other.

Two nuclei begin to form, surrounded by the fragments of the parent’s nuclear envelope.

Chromatin becomes less tightly coiled.

Question 11

name the stages in mitotic phase

Answer 11

prophase
prometaphase
metaphase
anaphase
telophase

Question 12

what happens during cytokinesis

Answer 12

the cytoplasm divides

Question 13

what happens once cytokinesis is finished

Answer 13

the cell splits into 2 daughter cells which return to interphase and the process repeats

Question 14

when does cell division stop

Answer 14

Cell division only stops when cells leave the cell cycle. Sometimes done intermittently, so for short period of time or for a long period of time.

Question 15

what are the 2 G phases involved in in interphase

Answer 15

involved in doubling the cytoplasm and centrosomes and other organelles (everything apart from DNA replication occurs in the G stages).

Chromatin is still condense but once moves into S phase we see DNA replication.

Question 16

what is ageing

Answer 16

As a cell ages it becomes less able to carry out the processes of interphase, mitosis and cytokinesis.

Question 17

what things impact upon aging

Answer 17

• May be programmed genetically (not be amenable to multiple rounds of cell division genetically)
  A number of factors contribute:
• Protein cross-links by glucose - diabetes
• Free radical damage – antioxidants on cell DNA
• Cessation of mitosis - Hayflick Limit ( a property all cells have – the limit of cell replication, imposed by the shortening of the telomeres with each division)

Question 18

what is controlled cell death call and explain it

Answer 18

known as apoptosis,

this is a normal and natural way for cells to be disposed of once at end of their cell life. To prevent them from doing damage to the cells in which they’re contained