Molecular biology

Question 1

Why are H bonds between nitrogenous bases important?

Answer 1

They confer thermodynamic stability to the structure

Question 2

Which are the codes used to identify the major and the minor grooves?

Answer 2

Major groove –> ADAM/MADA for A:T/T:A, AADH/HDAA for G:C/C:G
Minor groove –> AHA for A:T/T:A, ADA for G:C/C:G

Question 3

How can we distinguish the major and minor grooves by looking at the oxygen on the deoxyribose?

Answer 3

On the left backbone, the deoxyribose points is oxygen up on the major groove and down on the minor groove.
On the right backbone the opposite is true because the chains run antiparallel

Question 4

How can we have the formation of alternative base pairing?

Answer 4

1. Reverse Watson-Crick bonding is due to base flipping of one of the bases
2. Hoogstein base pairs form when we have both the rotation of a purin around its glycosidic bond and base flipping

Question 5

Which are the configurations that DNA can assume under electron microscopy?

Answer 5

1. B DNA
2. A DNA
3. Z DNA
4. Cruciform
5. Triple stranded DNA
6. Curvature

Question 6

What are dNTPs and why are they important?

Answer 6

They are nucleoside triphosphates containing deoxyribose and are the substrates for dna synthesis

Question 7

How can dNTPs be formed?

Answer 7

Either by de novo biosynthesis or by salvage pathways involving nucleoside reutilization by nucleoside kinases

Question 8

What does mtDNA encode for?

Answer 8

1. 13 proteins of oxydative phosphorylation
2. 24 RNA molecules for intramitochondrial protein synthesis

Question 9

Which region of the mtDNA regulates its replication, transcription and translation?

Answer 9

The dispacement (d) loop