Cell cycle

Question 1

Nuclear division (mitosis) and cytoplasmic division (cytokinesis) are 2 phases known as ___ phase and can be seen in a microscope

Answer 1

M

Question 2

Interphase can be divided into phases. The only phase that can be seen microscopically is ___ phase. The other main phases are called ___ (because under a microscope not much is happening)

Answer 2

S

Gaps

Question 3

What are the three distinct periods in interphase?

Answer 3

Gap period (G1)
Synthetic period (S)
Gap period (G2)

Question 4

What happens in G1 at interphase?

Answer 4

The cell grows and carries out normal metabolic and biochemical functions

Question 5

What happens in S at interphase?

Answer 5

DNA synthesis (replication)

Question 6

What happens in G2 at interphase?

Answer 6

centrioles (spindle pole bodies) duplicate

Question 7

When does a cell go into G0 (quiescence)?

Answer 7

If something goes wrong a cell goes into G0. It dies if the conditions don’t improve. However, if conditions improve, it goes into G1.

Question 8

The length of the cell cycle is ____ variable

Answer 8

very

Question 9

Where does most of the variability in the cell cycle take place?

Answer 9

during G1. Other phases are fairly constant in length

Question 10

When does the critical checkpoint (START) take place?

Answer 10

At the end of G1

Question 11

What happens if growth/environment is unfavourable?

Answer 11

Cells do not pass START

Question 12

How is the cell cycle regulated?

Answer 12

Cytoplasmic control factors
Cell division and cell size
External growth factors
Senescence (ageing)
Loss of control

Question 13

What happens to cells if cell cycle time was constant and nutrition is insufficient?

Answer 13

Cells would be too small on entering division so cells get smaller and smaller

Question 14

What happens to cells when food becomes scarce (with nutritional control?

Answer 14

Cell size is maintained. The cell cycle lengthens

Question 15

Cells which respond to growth factors have special _________ on their membranes

Answer 15

(TK) receptors

Question 16

The ability to change the normal growth rate is important in ________ healing

Answer 16

wound

Question 17

Growth factors trigger activation of ___ proteins which in turn accelerate the rate of cell growth and division

Answer 17

ras

Question 18

The probability of entering G0 depends on the number of times the cell has already ________

Answer 18

divided

Question 19

As you get older, the number of cell cycles _______

Answer 19

decreases

Question 20

The process of senescence is linked with _________ shortening

Answer 20

telomere

Question 21

Raising levels of telomere in patients may slow down _______, but also increases the risk of developing cancer

Answer 21

ageing

Question 22

What are the four strategies in which the number of cells in an adult tissue can be kept constant?

Answer 22

No renewal i.e. tissues with permanent cells
Renewal by simple duplication
Renewal by stem cells
Renewal by multipotent stem cells

Question 23

If a cell has differentiated can it change its specialised character in diverse environments?

Answer 23

No, once it has differentiated, it maintains its specialised character

Question 24

Which cells don’t undergo renewal and don’t appear to divide and cannot be replaced if they are lost or damaged?

Answer 24

Nerve cells
Heart muscle cells
Lens cells of the eye

Question 25

Renewal by simple duplication - cells are constantly dying and being replaced. Rates of renewal vary considerably: e.g.
gut lining ___-____ days
pancreas > 1 year

Answer 25

3-6

Question 26

Stem cells are NOT differentiated by are________

Answer 26

determined (pre-specified)

Question 27

Stem cells divide ______ or ________

Answer 27

symmetrically or asymmetrically

Question 28

Renewal by multipotent stem cells e.g. _______

Answer 28

Blood cell formation (haemopoiesis)

Question 29

What does totipotent mean?

Answer 29

ability of a single cell to divide and produce all of the differentiated cells in an organism, including extra-embryonic tissues

Question 30

What does pluripotent mean?

Answer 30

stem cells that have he potential to differentiate into any of the three germ layers

Question 31

What does multipotent mean?

Answer 31

describes cells which have the potential to differentiate into multiple, but limited cell types