Gene expression

Question 1

Base substitution, 3 possibilities

Answer 1

1) sub of stop codon: significantly diff protein
2) change of primary structure of protein, may not function properly
3) degen code means nothing happen

Question 2

Base deletion

Answer 2

Frame shift created, huge impact

Question 3

Causes of mutation

Answer 3

Radiation, disrupt structure of DNA

Chemicals, alter structure of DNA or interfere with transcription

Question 4

Transcription factor

Answer 4

Molecule that switches on gene that moves from the cytoplasm to nucleus

Question 5

How might transcription factor activate gene

Answer 5

Binds to specific base sequence of DNA. causes DNA region to begin transcription.

Question 6

Oestrogen switching on gene

Answer 6

Lipid soluble, diffuses through cell-surface membrane easily.
In cytoplasm, binds on complementary shaped stie of receptor molecule of transcriptional factor. This changes shape of transcriptional factor and now can bind to DNA.
Enter nucleus and starts transcription

Question 7

Epigenetics

Answer 7

Environmental influences can alter genetic inheritance

Question 8

How can DNA-histone complex affect transcription

Answer 8

More condense = inhibition because not accessible by transcription factors

Question 9

How does acetylation of histones affect transcription

Answer 9

Decreased acetylation = more positive charge on histone, increasing attraction to phosphate on DNA, more condensed. Gene switched off

Question 10

How does methylation of DNA affect transcription

Answer 10

Addition of CH3 to cytosine bases, prevents binding of transcriptional factors, attracts proteins that condense DNA-histone complex

Question 11

How can translation of mRNA be inhibited

Answer 11

Large double stranded molecules of RNA broken down by enzyme into siRNA.
One of the strands of siRNA combines with enzyme
siRNA guides enzyme to a messenger RNA by pairing complementary bases on seecction of RNA and enzyme cuts mRNA into smaller sections.
No longer can translate poilypepirde.

Question 12

Malignant tumour and benign tumour differences

Answer 12

googler

Question 13

oncogene

Answer 13

Mutated protooncogene that is perma activated

Question 14

protooncogene

Answer 14

Stimulate cell to divide when growth factors attach to protein receptor on surface membrane

Question 15

How can protooncogene be perma switched on

Answer 15

Mutation means that protooncogene is permanently activated, increasing production of proteins that encourage cell division and stimulates cells to divide uncontrollable.

Question 16

Tumour suppressor gene

Answer 16

Gene that slows cell div, repairs mistakes in DNA and stimulates apoptosis

Question 17

Abnormal methylation of tumour suppressor gene

Answer 17

Hypermethylation of promotor region leads to inactivation of gene. Transcription of promotor regions inhibited. Reduced production of proteins responsible for apoptosis so cell divide uncontrollably

Question 18

Why use log scale

Answer 18

When large range of results

Question 19

siRNA

Answer 19

double stranded siRNA becomes single stranded and associates with enzyme. it is complementary to target mRNA. In cytoplasm binds using complementary base pairs and enzyme cuts mRNA so cannot be translated.