MOLECULAR BIOLOGY OF THE GENE

Question 1

how many codons are there?

Answer 1

64

Question 2

how many amino acids are there?

Answer 2

20

Question 3

which base is degenerate?

Answer 3

3rd

Question 4

what is the start codon?

Answer 4

AUG codes for methionine (Met)

1st AA in a polypeptide

Question 5

what is the one gene -one protein hypothesis?

Answer 5

o

Question 6

what is alternative splicing?

Answer 6

exons can be joined together in a

variety of ways

Question 7

what can errors in gene expression cause?

Answer 7

many uncommon disorders
can also influence the predisposition of many common diseases such as breast cancer, lung cancer, prostate cancer and blood cancer

Question 8

how do transcription errors lead to disease?

Answer 8

Over-expression of the TF MYC is found in numerous cancers

If one copy of the gene encoding the TF is mutated this can also lead to disease

Question 9

what is haploinsufficiency?

Answer 9

where one copy of the gene is not enough e.g. p53 gene

Question 10

what is dominant mutation?

Answer 10

where a change in the gene sequence generates change in the protein that exerts dominance over the wild-type e.g. TFCP2L3 gene and genetic deafness

Question 11

how do mRNA processing errors occur?

Answer 11

involves errors in alternative splicing

Question 12

how does cystic fibrosis occur?

Answer 12

Mutations found in the exon 7 of SMN1 gene.

As a result, the exon 7 is skipped and the protein produced is non-functional

Question 13

what are mRNA translation errors?

Answer 13

Mutations that affect translational efficiency

Question 14

give examples of mutations in key translation proteins that lead to diseases

Answer 14

Translation initiation factors, e.g. eIF2 gene - a neurodegenerative disease called VWM
Release factors, e.g. eRF3 gene – gastric cancer
Mutations affecting the tRNA transfer proteins or the ribosome itself

Question 15

what is Gel Electrophoresis of DNAs/RNAs?

Answer 15

g

Question 16

how does gel electrophoresis work?

Answer 16

DNA is negatively charged (-):
Anode (-)
Cathode (+)
So will move from the anode to the cathode

Question 17

what is produced from gel electrophoresis?

Answer 17

A gel image loaded with DNAs

Question 18

what is western blot?

Answer 18

w

Question 19

what is western blot used for?

Answer 19

to detect proteins

Question 20

what are the steps involved in western blotting?

Answer 20

Sample preparation
Gel Electrophoresis
Blotting (or transfer)
Blocking
Antibody Probing
Detection

Question 21

how can we detect gene expression?

Answer 21

Polymerase Chain Reaction (PCR)

Question 22

what is PCR?

Answer 22

p

Question 23

what does PCR allow?

Answer 23

Enables the amplification of a specific region of DNA from just a single molecule of starting material

Question 24

what does gene expression profiling allow?

Answer 24

Detects how many copies of a gene (genes) you have

Idea of the regulation of gene expression at a given time

Question 25

what is PCR used for?

Answer 25

Diagnostics
Gene cloning
Legal disputes