Nucleic Acids

Question 1

What’s the name of the bond between nitrogen bases and pentose rings?

Answer 1

N beta glycosyl bonds

Question 2

What’s the bonding positions of purine and pyrimidines with respect to the bases?

Answer 2

N-1 of pyrimidine and N-9 of purine

Question 3

What is the configuration of nucleotide pentoses?

Answer 3

Beta-furanose (five membered ring)

Question 4

What part of DNA is reduced giving it its name deoxy?

Answer 4

2’ carbon of ribose sugar

Question 5

What is the end product of RNA hydrolysis?

Answer 5

Ribonucleotide 3’-monophosphate

Question 6

What are the tautomeric forms of uracil?

Answer 6

Lactam, lactim, and double lactim

Question 7

In what wavelength does a nucleic acid absorbs light?

Answer 7

260nm

Question 8

What are the functional groups of purine and pyrimidines?

Answer 8

Carbonyl group, exocyclic amino groups, and nitrogens

Question 9

What are the four rules of Chargaff for?

Answer 9

Base composition

Question 10

What is the orientation of Watson and crick DNA model?

Answer 10

Right handed helix

Question 11

What is the conformation of the beta furanose of deoxyribose in DNA?

Answer 11

C-2’ endoformation

Question 12

What is the distance between the bases in a DNA molecule?

Answer 12

3.4 angstrom

Question 13

What is the secondary repeat distance of the DNA molecule?

Answer 13

34 angstrom

Question 14

How many bases pairs are in one complete turn of DNA helix?

Answer 14

For 34 A repeats its 10 base pairs in solid/super helical state and for aqueous media its 10.5

Question 15

What is more stable AT or GC?

Answer 15

GC due to presence of a triple bond

Question 16

What’s the distance between the two strands of DNA molecule?

Answer 16

About 20 A

Question 17

What are the two conformations of purines?

Answer 17

Anti and syn

Question 18

What is the conformation of pyrimidines?

Answer 18

Anti

Question 19

In what conformation is the Watson and crick model of DNA/

Answer 19

B form

Question 20

What conformation of DNA is present in case of dehydration?

Answer 20

A form

Question 21

What are the characteristics of A form DNA?

Answer 21

11 base pairs per turn instead of the b form 10.5 and 20 degree tilt, major grooves are much more deeper and minor grooves shallower

Question 22

What is the conformation of b and a form DNA

Answer 22

Right handed

Question 23

What form of DNA conformation has zigzag like appearance?

Answer 23

Z form

Question 24

How many base pairs are present in Z conformation of DNA?

Answer 24

12 base pairs per turn

Question 25

What is the distance between base pairs in A form DNA?

Answer 25

2.6 A

Question 26

What is the distance between Z form DNA base pairs?

Answer 26

3.7 A

Question 27

What is the glycosyl bond conformation in A and B form?

Answer 27

Anti

Question 28

What is the glycosyl bond conformation in Z form?

Answer 28

Anti for pyrimidines and syn for purines

Question 29

What is the state of grooves in z form conformation of DNA?

Answer 29

Major grooves are not apparent whereas minor grooves are narrower

Question 30

What is the characteristic of inverted repeats?

Answer 30

They can form hairpin or cruciform structures

Question 31

What are mirror repeats?

Answer 31

When inverted repeats occur in both strands they are called mirror repeats

Question 32

What doesn’t forms structural bends or loops in DNA?

Answer 32

Mirror repeats

Question 33

What forms the hairpin or cruciform structures

Answer 33

Palindrome sequences (hairpin if in one strand and cruciform if in both strands)

Question 34

What is mono or polycistronic?

Answer 34

If the DNA codes for only one type of protein it’s mon and vice versa for multiple

Question 35

What is the the orientation of ssRNA?

Answer 35

Right handed