Lecture 30 - Neo 4

Question 1

What is an example of a factor that can influence the expression of epigenetic markers?

Answer 1

Diet, Psychological state, social interactions, alternative medicine, therapeutic drugs etc.

Question 2

What needs to happen to the chromosome for transcription to be able to occur?

Answer 2

The histone needs to be open for transcription to be able to occur

Question 3

What is the effect of methylation of the DNA?

Answer 3

Histones causes nucleosomes to pack together more tightly

Question 4

What is the effect of acetylation of the DNA?

Answer 4

Causes loose packing of histones

Question 5

What is the effect of point mutations?

Answer 5

May be silent or have a profound effect

Question 6

What is the effect of frameshift mutations?

Answer 6

Alteration of the open reading frame (quite a significant effect)

Question 7

What is the effect of chromosome mutations?

Answer 7

Karyotype instability

Question 8

In general terms how can genetic mutations lead to the formation of neoplasms?

Answer 8

Either increase cell growth or decrease the amount of cell death

Question 9

Genomic stability is a balance between _____(1)_____ and _____(2)_____.

Answer 9

1. Tumour suppressors

2. Oncogenes

Question 10

One mutation will lead to a cancer

True/False

Answer 10

False - however, once you get one mutation this will trigger the development of more mutations and thus increases the likelihood of getting cancer

Question 11

To get a cancer do you need to get a defect in both of the chromosomes or proto-oncogenes and tumor suppressors?

Answer 11

Tumour suppressors - require a loss of both of the suppressor genes to get cancer

Proto-oncogenes - you don’t necessarily have to have a mutation of both of these to get problems

Question 12

What is the function of p53 protein within the S-phase and what are it’s options if it encounters a problem and what is it activated by?

Answer 12

p53 is activated by Rb

it checks for DNA mutations, if it should find one it would either induce DNA repair or enter apoptosis

Question 13

What is the function of cyclins and CDK’s?

Answer 13

cell cycle activation

Question 14

What is the difference between a proto-oncogene and an oncogene?

Answer 14

Proto-oncogene = simply the gene before it became mutated and contributes to neoplasia

Oncogene - once it has been mutated and starts to contribute to cancer

Question 15

What are the effects that oncogenes can have on growth factor pathway?

Answer 15

1. Excess growth factor
2. Excess growth factor receptors
3. Mutant growth factor receptor so starts signalling on its own accord
4. Mutant signal transducer
5. Mutant transcription factor

Question 16

Does Rb promote or suppress tumours?

Answer 16

Rb is a tumour supressor

Question 17

What is the function of P16?

Answer 17

promotes inhibitory effect of RB

Question 18

What is the function of p57, p27 and p21?

Answer 18

They can inhibit all CDK’s

Question 19

What is p27 induced by?

Answer 19

TGF-b

Question 20

What is p21 induced by?

Answer 20

p53

Question 21

How is replicative immortality achieved?

Answer 21

Telomerase - generally only expressed within stem cells and sperm/egg cells. It adds building blocks back onto the genes allowing you to keep on going forever. All cells have the gene encoded for these it is only in specific cells that they are turned on. However, cancer has the ability to activate these.