Mod 6: RNA biology

Question 1

what is different about the chemical structure of RNA compared to DNA

Answer 1

contains 2’ - OH
whereas DNA lacks this group (hence deoxy)

also, no thymine, only uracil

see onenote for structure

Question 2

what does this difference mean for the RNA’s stability?

Answer 2

makes it less stable than DNA

Question 3

what is the difference between uracil and thymine

Answer 3

uracil doesn’t have the methyl group whereas thymine does

Question 4

what are the 5 main roles of RNA

Answer 4

• transfer of info from DNA to proteins (via mRNA that codes for proteins)
• synthesis of proteins (via rRNA and tRNA)
• processing mRNA (small nuclear RNA i.e. snRNA, which is involved in splicing introns from pre mRNA)
• processing and modifying rRNA (via small nucleolar RNA i.e. snoRNA)
• catylitic RNA (e.g. self splicing introns, rybozymes)

Question 5

how much RNA does a single cell contain in pg

Answer 5

10 picograms (10^-11 g)

Question 6

what % RNA is ribosomal RNA

Answer 6

80-85%

Question 7

what % RNA is low molecular weight (e.g. tRNA, snRNA etc)

Answer 7

10-15%

Question 8

what % RNA is mRNA

Answer 8

1-5%

Question 9

what part of the RNA is hydrophobic and which is hydrophilic

Answer 9

the ribose sugar and phsophate backbone is hydrophilic

the organic bases are hydrophobic

Question 10

what does a strand of RNA do to increase its stability

Answer 10

uses self complementarity to form base pairs with itself to forms secondary structure

this makes base pads, kinda loops over on itself

gives it a tertiary structure

see onenote

Question 11

how is the secondary structure formed

Answer 11

via palindromic sequences (ie self complementary bases)

which are seperated by a random sequence that isnt related

the slef complementary bases can loop over to pair to each other and form stem loop structure

see onenote

Question 12

what is the name of the type of sequence that forms this secondary structure

Answer 12

hyphenated dyad symmetry
(hyphen cuz of the useless sequence in the middle of the two complementary sequences)

Question 13

what are the 3 ways the usage/amount of RNA can be regulated

Answer 13

1) controlling the synthesis - its transcription, so whether or not it’s made, can be turned on and off rapidly
- e. g. lac operon

2) regulating its degradation - after its made, due to its lack of stability, if it’s not made stable it’ll just degrade away
- e.g. trnasferrin receptor mRNA

3) its translation effieciency - proteins can control the usage of certain RNAs
- e.g. ferritin mRNA

Question 14

what region regulates the degradation of RNA and its translation efficiency?

Answer 14

UTR

Question 15

transferrin receptors as an example of degradation regulation - see onenote for diagram and explanation

Answer 15

:)

Question 16

What is the protein called that binds to 5’ UTR and 3’ UTR in RNA

Answer 16

Iron Response Element - Binding Protein
or just
IRE-BP

see OneNote for where its used

Question 17

Ferritin genes as an example of translation regulation in RNA- see one note for diagram and explanation

Answer 17

:)