Gene Expression 2

Question 1

What molecule can inhibit translation of mRNA

Answer 1

RNA Interference

Question 2

Describe the work of RNA Interference

Answer 2

Enzyme cuts large double stranded molecule of RNA into smaller sections called Small interfering RNA
One of the SiRNA strands combines with an enzyme and guides it to MRNA by paring bases
Enzyme cuts mRNA into smaller sections
so mRNA cannot make a polypeptide

Question 3

Define proto-oncogene

Answer 3

Stimulates a cell to divide when growth factor attaches to a protein receptor on csm which activates the gene

Question 4

Define oncogenes

Answer 4

mutation of proto-oncogenes that can be prematurely activated

Question 5

Name two ways oncogenes can become permanently activated

Answer 5

receptor protein is permanently activated so cell division despite absence of growth factors
Oncogene can code for growth factor produced in excessive amounts

Question 6

Define Tumour Suppressor genes

Answer 6

slows cell down cell division
repair DNA mistakes
stimulates apoptosis

Question 7

How can oestrogen cause a tumour?

Answer 7

bind to the receptor that promotes cell division and growth to cause a tumour

Question 8

Define Genome

Answer 8

All genetic material of an organism

Question 9

What type of sequences are used to understand the genome

Answer 9

WGS

whole-genome shotgun sequencing

Question 10

Why is bacteria proteome easy to find?

Answer 10

Vast majority have one circular piece of DNA not with histone
no introns

Question 11

Describe how oestrogen stimulates the transcription of genes

Answer 11

o. is lipid soluble so diffuses through phospholipid bilayer
In the cytoplasm it binds to the receptor on the transcriptional factor
O. changes the shape of the DNA binding site and is activated
Transcriptional Factor enters the nucleus via pore and binds to specific DNA sequence
Stimulates transcription of the genes

Question 12

Define epigenetics

Answer 12

Epigenetics involves heritable changes in gene function without changes to the base sequence of DNA

Question 13

Name some features of benign tumours

Answer 13

normal nucleus
specialised cells
contains adhesion molecules
presence of a capsule
localised effect

Question 14

Name some features of malignant tumours

Answer 14

larger and darker nucleus
unspecialised cells
no adhesion molecules
no casule
life threatening 
systematic effects
requires chemo and radiotherapy

Question 15

Describe how oestrogen works to begin transcription

Answer 15

Oestrogen is lipid soluble so passed through phospholipid bilayer and enter the cytoplasm
It binds to the receptor on the transcription factor and changes the shape of the DNA binding site and hence activates it
Transcription factor enters the nucleus via the nuclear pore and binds to specific/complementary DNA sequence
Transcription of that gene is stimulated

Question 16

Define the epigenome

Answer 16

chemical tags that determine the shape of the DNA complex

Question 17

What is epigenetic silencing?

Answer 17

When inactive genes are tightly arranged so they cannot be read.