Control Of Gene Expression

Question 1

What is a gene mutation

Answer 1

Change in DNA base sequence of a gene

Question 2

What is the impact of mutations

Answer 2

Results in different amino acid sequence in primary structure which causes hydrogen and ionic bonds to form in different location. This change this tertiary structure resulting in a different 3D shape therefore the protein could become inactive. Can also lead to mutations that cause cancer

Question 3

What are the 6types of mutation

Answer 3

Addition,deletion, substitution, inversion, duplication and translocation

Question 4

What is an inversion mutation?

Answer 4

Section of DNA bases detach from DNA sequence and when they rejoin they are inverted so this section of code is back to front

Question 5

What is a duplication mutation

Answer 5

One particular base is duplicated at least once in the sequence causes a frame shift to the right.

Question 6

Translocation mutation?

Answer 6

Section of bases on one chromosome detaches and attached onto a different chromosome. Affects the phenotype

Question 7

What are stem cells

Answer 7

Undifferentiated cells that can continually divide and become specialised

Question 8

What are the 4 different stem cells

Answer 8

Totipotent, multi potent, uni potent, pluripotent

Question 9

What is a totipotent stem cell

Answer 9

Can divide and produce any type of body cell. Found in embryo

Question 10

What is pluripotent stem cell

Answer 10

Can divide into unlimited numbers and can be used in treating human disorders. Found in embryos

Question 11

What ar unipotent stem cells

Answer 11

Can only differentiate into 1 type of cell (cardiomyocytes)

Question 12

What are multi potent stem cells

Answer 12

Only differentiate into a limited number of cells

Question 13

What are induced pluripotent stem cells

Answer 13

Produced from adult somatic cells using transcription factors.
Genes that were switched off to make cell specialised must be switched on

Question 14

What are transcription factors

Answer 14

Control transcription in eukaryotic cells.

Question 15

How do transcription factors work?

Answer 15

Transcription factor (protein) binds to specific base sequence of DNA and initiates transcription of genes.
Once bound transcription can begin creating mRNA which is then used in translation to create protein

Question 16

What would happen without transcription factors

Answer 16

Gene is inactive and protein won’t be made

Question 17

What is oestrogen

Answer 17

Steroid hormone that initiates transcription

Question 18

How does oestrogen intimate transcription

Answer 18

Binds to receptor site on transcription factor
When it binds it causes it to change shape slightly which makes it complementary and able to bind to DNA to initiate transcription

Question 19

What is epigenetics

Answer 19

Heritable changes in gene function without changing the DNA base sequence. Changes are caused by changes in environment and can inhibit transcription.

Question 20

How does methylation of DNA inhibit transcription

Answer 20

When methyl groups are added to DNA, they attach to the cytosine bases
This prevents transcription factors from binding and attracts proteins that dense the DNA histone protein complex.
Methylation of DNA prevents a section of DNA from being transcribed

Question 21

How does a decrease in acetylation of histone proteins inhibit transcription

Answer 21

A decrease in the number of acetyl groups bound to histone proteins inhibits transcription
If acetyl groups are removed from the DNA then the histone become more positive and are attracted to phosphate group on DNA.
This makes DNA and histone more strongly associated and harder for transcription factors to bind

Question 22

What does RNA interference do

Answer 22

Inhibit translation

Question 23

How does RNAi inhibit translation

Answer 23

An enzyme cuts mRNA into small interfering RNA
One strand of siRNA combines with another enzyme
This siRNA complex will bind via complementary base pairing to another mRNA molecule.
Once bound the enzyme will cut up the mRNA molecule so it can’t be translated