Lecture 12 - Structure of RNA

Question 1

What does RNA stand for?

Answer 1

Ribonucleic acid

Question 3

What is RNA a product of?

Answer 3

Product of transcription from a DNA template

Question 4

How much RNA is in a cell?

Answer 4

10x more than DNA
10pg RNA

Question 5

In what 3 ways is RNA different to DNA?

Answer 5

Chemical structure
Physical properties
Biological role

Question 6

How is RNA different to DNA in terms of chemical structure?

Answer 6

Uses ribose not deoxyribose
Uracil is used not thymine
RNA is less stable

Question 7

How is RNA different to DNA in terms of physical properties?

Answer 7

Single stranded
Can base pair with itself and fold into complex structures

Question 8

How is RNA is different to DNA in terms of biological role?

Answer 8

Transfer of info from DNA to protein
Synthesis of proteins
Processing of messenger
Processing and modification of ribosomal RNA
Catalytic RNA

Question 9

How does an RNA secondary structure form?

Answer 9

RNA is a palindromic sequence
It can do self complementary base pairing which means it can fold in half and bind to itself

Question 10

How is the regulation of RNA usage controlled?

Answer 10

Synthesis
Regulated degradation
Translation efficiency

Question 11

How is synthesis used to regulate RNA usage?

Answer 11

Transcription can be turned on or off rapidly
eg Lac operon

Question 12

How is regulated degradation used to regulate the usage RNAs?

Answer 12

Transferrin receptor mRNA

Question 13

How is translation efficiency used to regulate RNA usage?

Answer 13

Proteins can control the usage of some RNAs

Question 14

How does the transferrin receptor work?

Answer 14

• Iron in the blood binds to transferrin
• Its transported into the cells by a receptor
• If theres enough intracellular iron, the transferrin receptor mRNA is degraded

Question 15

How is the transferrin receptor regulated?

Answer 15

• RNA 2 structure regulates transferrin receptor mRNA degradation
• If theres no iron, the iron response element binding protein will bind to 3’-UTR
• RNA is stable so the receptor is made in the presence of iron
• Iron response element binding protein binds to iron and the protein dissociates form 3’-UTR
• The RNA is degraded so the receptor is not made

Question 16

What is the ferritin gene?

Answer 16

Ferritin binds to iron within the cell
When there’s low iron the iron response element binding protein binds to iron and prevents translation initiation