B4 pt 1

Question 1

What happens when we grow

Answer 1

When we grow our cells need to divide in order to make new cells. These stem cells need to specialise into different types of cells as stem cells are unspecialised

Question 2

What is mitosis for

Answer 2

Growth and repair of cells

Question 3

What is meiosis for

Answer 3

Used to make sex cells (gametes)

Question 4

What is interphase?

Answer 4

Between cell divisions, all cells undergo interphase. During interphase, the cell still carries out the function of the cell that is dividing.

Question 5

G1 phase

Answer 5

Cellular contents, excluding the chromosomes, are duplicated. For the organelles to duplicate, a lot of protein is required. Transcription and translation is the body’s way of making proteins so we can duplicate our organelles. Also, the size of the cell increases. This is to make sure that the daughter are the correct size after duplication.

Question 6

S phase (synthesis)

Answer 6

Each of the 46 chromosomes is duplicated by the cell. DNA synthesis occurs and DNA is used to duplicate the chromosomes

Question 7

G2 phase

Answer 7

The cell double checks the duplicated chromosomes for error, making any needed repair. Transcription and translation also occurs to repair any damaged chromosomes and replace the energy stores used in the S phase. The size of the cell increases to make sure that the daughter cells are the correct size after duplication

Question 8

Mitotic phase

Answer 8

This is the phase where the cell splits in 2. Firstly, mitosis is where the chromosomes split into 2 separate nuclei within the same cell. Cytokinesis is where the cell divides into 2, each with one nuclei.

Question 9

The 3 checkpoints

Answer 9

G1 checkpoint
G2 Checkpoint
Metaphase/spindle checkpoint

Question 10

G1 checkpoint

Answer 10

This takes place before the S Phase and checks for 2 things:
1-There is a check to make sure that the cell has grown to the correct size
2-There is a check to see if there is any damaged DNA

Question 11

G2 checkpoint

Answer 11

This takes place at the end of G2 and before the mitotic phase and also checks 2 things:
1-There is a check to make sure that the cell has grown to the correct size
2-There is a check to see if there is any damaged cells

Question 12

Metaphase/Spindle checkpoint

Answer 12

Takes place before the mitotic stage. There is a check to see if the chromosomes are aligned on the mitotic spindle. If they are aligned properly, mitosis and cytokinesis can take place. However if they are not aligned properly, mitosis and cytokinesis cannot take place.

Question 13

G0 phase

Answer 13

G0 is when cell cycle arrest happens and is entered for 3 reasons:
1-When the cell has been fully differentiated e.g. adult neurons
2-If they have damaged DNA e.g. senescent cells
3-B-memory cells