B20 - Gene Expression

Question 1

Define a mutation.

Answer 1

A change in the base sequence of the DNA

Question 2

What is an example of a gene that is permanently turned on?

Answer 2

Genes coding for essential chemicals - enzymes involved in respiration

Question 3

What is a totipotent cell?

Answer 3

A cell that can develop into any kind of cell.

Question 4

Give an example of a totipotent cell.

Answer 4

An egg cell

Question 5

How can gene expression be prevented?

Answer 5

• Preventing transcription (therefore mRNA)
• Preventing translation.

Question 6

What are stem cells?

Answer 6

Undifferentiated dividing cells

Question 7

What do totipotent cells develop into?

Answer 7

Pluripotent

Question 8

What are pluripotent cells?

Answer 8

It exists during early embryonic development. These can develop into almost any type of cell.

Question 9

What are multipotent cells?

Answer 9

Adult stem cells that can divide into specific types of stem cells.

Question 10

What are unipotent cells?

Answer 10

Derived from multipotent cells, but can only differentiate into one type of cell.

Question 11

What are induced pluripotent stem cells?

Answer 11

Induced from unipotent stem cells, which are genetically altered to express genes

Question 12

What is the purpose of iPSC?

Answer 12

Turn on genes which were turned off.

Question 13

What is the advantage of iPSC over embryonic stem cells?

Answer 13

Overcomes ethical issues, and is capable of self-renewal

Question 14

Which type of tumour is cancerous?

Answer 14

Malignant

Question 15

Which tumour grows more rapidly?

Answer 15

Malignant

Question 16

What are benign tumours surrounded with?

Answer 16

A capsule of tense tissue so remain as a compact structure

Question 17

What are the two main genes which play a role in cancer?

Answer 17

Tumour-suppressant genes and oncogenes.

Question 18

What are proto-oncogenes?

Answer 18

Stimulate cells to divide when growth factors attach to a protein receptor on its cell-surface membrane

Question 19

What are two reasons why an oncogene can become permanently activated?

Answer 19

• The receptor protein is always switched on, even without the growth factor
• Oncogene may code for a growth factor which Is produced in excessive amounts

Question 20

Name three roles of a tumour suppressor gene.

Answer 20

• Slow down cell division
• Tell cells when to die [apoptosis]
• Repair mistakes in DNA

Question 21

How do tumour suppressor cells lead to mutations?

Answer 21

Becomes inactive after mutating, therefore cells grow out of control as it stops inhibiting cell division.

Question 22

Give some examples of tumour suppressor genes.

Answer 22

TP53, BRCA1 and BRCA2

Question 23

Which protein does TP53 code for?

Answer 23

P53 protein, which is involved in the process of apoptosis, which is activated when a cell can no longer repair its DNA.