2.8 Control of Cell division

Question 1

The divsion of cells can be described as

Answer 1

carefully coordinated

Question 2

What is the alternating process or enlargment and cell division known as

Answer 2

cell cycle

Question 3

the cells in our bodies that undergo rapid cell division are known as…

Answer 3

Stem cells (undifferentiated cells)

Question 4

What are the key triggers for a stem cell to divide

Answer 4

size and singals from the envrionment (cell inhibtion, growth hormones)

Question 5

What do external signals called grwoth factors (hormones) do

Answer 5

send messages for cells to divide

Question 6

How are grwoth factors recieved

Answer 6

Receptor molecules in the plasma membrane. They pass this message on to relay proteins which move through the cytoplasm to the nucleus

Question 7

What are the three main sections of interphase called

Answer 7

G1 (gap 1 or growth phase 1), S Phase (s = synthesis), G2 (Gap 2 or growth phase 2)

Question 8

What occurs during G1

Answer 8

Accumultion of energy (ATP/glucose/oil)

Question 9

During G1, the cell reaches checkpoint 1. What does this entail

Answer 9

The decsiion to divide - occurs when the cell is an appropirate size and has recieved an external signal to divide (growth factor)

Question 10

What occurs during S Phase

Answer 10

DNA is replicated

Question 11

What occurs during G2

Answer 11

cell reaches checkpoint 2 - makes sure DNA replication has occur properly

Presence of Mitosis Promoting Factor (MPF) starts mitosis

Question 12

Why does mitosis begin

Answer 12

Due to an increase in MPF

Question 13

Why does MPF levels rise

Answer 13

When CDK (enzyme) and Cyclin (substrate) combine to form MPF (creating an ezyme substrate complex

Question 14

What occurs at checkpoint 3:

Answer 14

Checked to see if sister chromatids area correctly attached to spindle.

Question 15

When does anaphase begin

Answer 15

When theres a drop in MPF

Question 16

In cytokenisis, one daughter cell differentiates and becomings specialised in its function whilst the other…

Answer 16

remains a stem cell and goes through the cell cycle again

Question 17

What are some extrenal factors that regulate the cell cycle

Answer 17

growth factors (hormones)
Physical signal contact inhibtion (cells need to have contact. When skin is cut and the cells on the edge of the gash will divide until they are touching other cells

Question 18

Name some internal factors that regulate the cell cycle

Answer 18

MPF controls mitosis
Cyclin is a regulatory protein (levels rise and fall) which attaches to an enzyme (Cdk) (levels remain the same throughout the cycle to produce MPF(checkpoint 2)
A rise in MPF (due to a rise in cyclin initiates mitosis and a drop in MPF intiates anaphase (checkpoint 3)

Question 19

Define cancer

Answer 19

Uncontrolled division of cells. Cancer cells produce daughter cells which both stay as stem cells and continue division or if orate

Question 20

What are some things cancer has been linked to

Answer 20

Chemical carcinoens: casuing change in nucleotide sequence of the DNA (e.g. checmicals in tobacco smoke)
Radiation: Cause chromosome breaks (e.g. x-rays/UV light)
Viruses: Cause an addition of foreign DNA sequences in the host DNA

Question 21

What is cell culturing

Answer 21

The ability to grow very small organisms in the labratory. This allows millions of cells to be grown in a small area, with hundreds of generations to be studied over a short time period.

Question 22

What can the ability of cell culturing to study many generations over a short period of time allow

Answer 22

Mutations to be detected, isolated and studied

Question 23

Culturing cells has occured over thousands of years including in foods such as&raquo_space;>

Answer 23

bread, alcohol, cheese, yoghurt

Question 24

What are the conditions required for cell culturing

Answer 24

An appropriate medium (agar or a broth)
Appropriate temp
Correct osmotic balance
Suitable pH
Oxygen (if aerobic)
Aseptic (free from any foreign bacteria)

Question 25

The culuting on cells can be conducted on only large scale levels. T or F

Answer 25

False- can occur on small scale production, using petri dishes, or large scale industrial using continuous flow cultures

Question 26

What are some contemporary examples of cell culturing

Answer 26

Cosmetic and drug testing
production of human tissues
Production of insulin
The ames tes (test is substance contains a carcinogen - food, makeup etc)
and possibly production of organs in the future

Question 27

Tissue culture in plants requires…

Answer 27

Donor cells - cut out from plant and then washed with alcohol or bleaaching agent to remove microbes that could contaminte the culture.

These then need to be placed in a solution containing: minerals; plant growth hormones, substance such as glucse for energy

Question 28

Name some advantages of cell culturing

Answer 28

can produce many cells/plants quickly as conventional methods could take years
can produce many cells/plants in a small area
could produce many desired plants which could be sold fro a high price

Question 29

Name some disadvantages of cell culturing

Answer 29

All cells produced are gentically identical. If a disease was present that killed a cell with a specific genetic makeup, all cells would die