DNA structure

Question 1

Which carbon atom of pentose is connected to the Phosphate group

Answer 1

C5

Question 2

Which carbon of pentose is connected to Base

Answer 2

C1

Question 3

Which carbon determines if it is ribose/deoxyribose

Answer 3

C2

Question 4

How do we describe the direction of the DNA strands
what is the direction we are talking about each individual strand

Is the DNA a left-handed or right-handed helix

Answer 4

Antiparallel

5’ to 3’

Right-handed

Question 5

How many bases is in each rotation

How much does each base rotate

Answer 5

10.4

Around 36 °

Question 6

Is the nucleic acid chiral. Where is the source of chirality

Answer 6

Yes

The D-ribose and D-deoxyribose

Question 7

What is the importance of the grooves on DNA

Answer 7

Major groove much more accessible for transcription factors

Mutations may disrupt minor groove binding properties and hence DNA structure

Protein binding at minor groove will distort protein structure much more severely

Question 8

Name the 2 pyramidines

Answer 8

Thymine, Cytosine, Uracil (Any 3)

Question 9

Name the 2 purines

Answer 9

Adenosine, Guanine

Question 10

Name the 5 ribonucleoside

Answer 10

uridine, cytidine, Adenosine, guanosine

Question 11

Name the 4 deoxynucleotide

Answer 11

deoxyadenylate, deoxyguanylate, deoxythymidylate, deoxycytidylate

Question 12

How many H bonds are formed between A and T

Answer 12

2

Question 13

What’s the difference between Uracil and Thymine

Answer 13

U has 1 less methyl group than T does

Question 14

How many H bonds are formed between C and G

Answer 14

3

Question 15

What are the 3 types of DNA.

What is the major type of DNA we are mentioning

What are the remaining 2 types special for

Answer 15

B-DNA, A-DNA, Z-DNA

B-DNA

A-DNA is More compact and the base is not perpendicular to the helix-axis

Z-DNA is a left-handed helix and the DNA winds to the left in a zigzag pattern

Question 16

What is the Rule aka Rule of Complementary Base Pairing

Answer 16

Chargaff’s Rule

Question 17

What is DNA wrapping around when condensed to form nucleosome

Answer 17

histones

Question 18

Name the 4 types of Histones

Answer 18

H2A,H2B, H3,H4

Question 19

What’s their function.

By how

Answer 19

They can control which part of DNA is exposed to Polymerase

Covalent Modification (methylation, acetylation, phosphorylation)

Question 20

What is the order of DNA structures (from low to high)

Answer 20

Loop (75000 bp)
–> Rosette (6 loop)
–> Coil (30 rosette)
–> Chromatid (10 coil)