Bases/Nucleosides/Nucleotides/Nucleic Acids

Question 1

List the purine bases.

Answer 1

Adenine and guanine

Question 2

List the pyrimidine bases.

Answer 2

Uracil, thymine and cytosine.

Question 3

Answer 3

uracil

Question 4

Answer 4

Thymine

Question 5

Answer 5

Cytosine

Question 6

Answer 6

Adenine

Question 7

Answer 7

Guanine

Question 8

What is DNA made of?

Answer 8

Nucleotides (base, phosphate, sugar)

Question 9

What is a nucleoside?

Answer 9

Purine/pyrimidine base linked to a 5 carbon sugar (pentose).

Question 10

Name a nucleoside with adenine and a ribose sugar.

Answer 10

Adonosine

Question 11

Name the nucleoside with guanine and deoxyribose.

Answer 11

Deoxyguanosine

Question 12

Name the nucleoside with cytosine and ribose.

Answer 12

Cytidine

Question 13

Name the nucleoside with thymine and deoxyribose.

Answer 13

Deoxythymidine

Question 14

Which can make more hydrogen bonds, ribose or deoxyribose?

Answer 14

Ribose

Question 15

Purines attach to the pentose at N__.

Answer 15

9

Question 16

Pyrimidines attach to the pentose at N__.

Answer 16

1

Question 17

Where are phosphates typically attached in NTPs (nucleotides)?

Answer 17

C-5’-OH

Question 18

A + deoxyribose + 1P =

Answer 18

deoxyadenosine 5’ monophosphate

Question 19

T + ribose + 1P =

Answer 19

ribothymidine 5’ monophosphate

Question 20

U + deoxyribose + 1P =

Answer 20

deoxyuridine 5’ monophosphate

Question 21

A nucleic acid polymer of nucleotides are linked by…

Answer 21

3’-5’ phosphodiester bonds (COPOC)

Question 22

How can you identify the ends of a nucleic acid?

Answer 22

5’C not invovled in a phosphodiester bond, 3’C not involved in a phosphodiester bond.

Question 23

List the properties of a base.

Answer 23

• heterocyclic
• aromatic, electron delocalization
• basically planar (slight pucker)
• **poorly **soluble in water
• largely hydrophobic with some polar groups

Question 24

What part of the nucleic acid is polar?

Answer 24

The sugar phosphate backbone

Question 25

Primary structure of nucleic acids is stabilized by...

Answer 25

Phosphodiester bonds

Question 26

Secondary structure of nucleic acids is stabilized by...

Answer 26

Base stacking interactions

Question 27

What is the over all charge of nucleic acids? What problem can this create and how is it avoided?

Answer 27

Overall negative charge of the backbones - could possibly repel eachother. Nucleic acid associates with positive groups to avoid.

Question 28

Why is nucleation (rezippering of denatured DNA) slow?

Answer 28

Base pairing has to be specific, as the complexitiy of the nucleic acid increases the more time it takes to nucleate.

Question 29

Which bp is more stable? Why?

Answer 29

GC, more **base stacking interactions**

Question 30

Define pKa

Answer 30

pKa is the pH at which hald a molecule is in its acid form and half is in the conjugate base form.

Question 31

What are the 3 effectors of T_m?

Answer 31

Salt concentration, pH and heat.

Question 32

Low salt concentrations ____ Tm

Answer 32

decreases

Question 33

Can RNA form a double helix?

Answer 33

Yes. **Intra**strand base pairing.