6.1 Cellular control

Question 1

What is an exon? (does it remain in the mRNA transcribed from that gene?)

Answer 1

the region of DNA that codes for a protein

the sequence remains in the mRNA transcribed from that gene

Question 2

what is an intron?

Answer 2

non-coding DNA

its sequence of DNA doesn’t remain in the mRNA transribed from that gene

Question 3

What are the 2 types of exon mutations?

Answer 3

point mutation

indel mutation

Question 4

what are the 3 types of exon’s point mutations?

Answer 4

silent
missence
nonsence

Question 5

what happens in a silent mutation?

Answer 5

(point mutation) no change in amino acid produced

Question 6

what happens in a missence mutation?

Answer 6

(point mutation) 1 amino acid changed to another

Question 7

what happens in a nonsence mutation?

Answer 7

(point mutation) amino acid codon replaced by stop codon

Question 8

What is the difference between the 2 types of exon mutations?

Answer 8

point- one base replaces another

indel- insertion or deletion of base causing FRAME SHIFT

Question 9

What ‘shift’ does an indel mutation cause and what does it mean?

Answer 9

frameshift= every amino acid after mutation is changed

Question 10

What is the example of gene regulation at a transcriptioal level?

Answer 10

if glucose is absent e.coli needs to produce enzymes to metabolise lactose:
Lac Operon gene in absence of glucose- (i.e. glucose doesnt need to be metabolied because there is glucose)
regulator gene is expressed, repressor protein synthesized, one site binds to lactose and one to operator region, repressor protein binds to operator region covering part of RNA polymerase binding site- the promotor region so RNA polymerase can’t bind sso structural genes aren’t transcribed, no translation, no enzymes

Lac operon in presence of glucose:
lactose binds to repressor protein, changing repressor proteins shape, leaves operator region, RNA polymerase can bind to promoter, transcribe genes into the enzymes and break down lactose