L1 -

Question 1

Nucleoside

Answer 1

A base and a pentose sugar covalently bonded by a glycosidic bond linking C1’ (sugar) and N9 (purine)/N1 (pyrimidine)

Question 2

Nucleotides are joined by…

Answer 2

phosphodiester bonds between 3’ OH (sugar1) to attached phosphate to 5’ OH (sugar2)

Question 3

When writing out nucleotides, how are they written?

Answer 3

5’ to 3’

Question 4

Where were the main three genetic experiments that proved DNA was our genetic material?

Answer 4

~ 1928 Griffith
~ 1944 Avery et al.
~ 1952 Hershey & Chase

Question 5

What’s the difference between ribose and deoxyribose?

Answer 5

Deoxyribose has a H not OH on C2’

Question 6

What are the five bases? SPELL

Answer 6

Adenine (Pur)
Guanine (Pur)
Thymine (Pyr)
Cytosine (Pyr)
Uracil (Pyr)

Question 7

What are bases?

Answer 7

~ planar conjugated rings
~ uncharged in physiological conditions
~ prime notation not used

Question 8

Tautomer

Answer 8

a molecule in which a proton has migrated to a different place

Question 9

Base tautomerisation

Answer 9

~ bases can exist as tautomers

~ implications for accuracy of DNA replication + therefore provides genetic variability

Question 10

Nucleotide

Answer 10

Nucleoside + phosphate

Question 11

Give four examples of alternative functions for nucleotide monomers.

Answer 11

~ ATP
~ CoA
~NAD(H)/NADP(H)
~FAD(H2)

Question 12

Chargaff’s rule

Answer 12

1. amount of purine bases = amount of pyrimidine bases

2. G=C & A=T

Question 13

Describe what the X-ray diffraction analysis of DNA showed.

Answer 13

Frankin & Wilkins
~ helical structure characteristic
~ spring of the lines showed:
1. 3.4nm and ~10 bp/turn
2. 0.34nm rise per bp
3. helix diameter = 2nm

Question 14

Watson and Crick used models to…

Answer 14

figure out:
~ A pairs with T with 2 H-bonds
~C pairs with G with 3 H-bonds
~ as they had similar widths

Question 15

Two complementary DNA strands are…

Answer 15

1. antiparallel

2. wind around each other in a clockwise direction

Question 16

Which parts of the DNA molecule are hydrophobic and hydrophilic?

Answer 16

Hydrophobic = bases in inside
Hydrophilic = sugar phosphate backbone

Question 17

How is the DNA stabilised?

Answer 17

~ via Van der Waals interactions between bases

~ base stacking - dependant on neighbour bases

Question 18

Confirmed structure of DNA

Answer 18

1980 crystal structure of DNA

1. 3.4nm and 10.5 bp/turn
2. 0.34nm apart
3. helix diameter = 2nm
4. it has major and minor grooves

Question 19

What gives the DNA molecule its strength?

Answer 19

~ VdW IMF
~ hydrophobic/philic interactions
~ H-bonds are weak

Question 20

What do the major and minor grooves in the DNA do?

Answer 20

they govern interactions with other molcules

Question 21

Which is the predominant DNA configuration in cells?

Answer 21

B-DNA