1B: More Biological Molecules

Question 1

What DNA Stands for

Answer 1

Deoxyribonucleic Acid

Question 2

What RNA stands for

Answer 2

Ribonucleic Acid

Question 3

Nucelotide Structure

Answer 3

Phosphate, Pentose sugar (Deoxyribose or Ribose), and a nitrogen-containing base

Question 4

Polynucelotide Structure

Answer 4

Sugar-Phosphate Backbone held together by ester bonds with bases

Question 5

DNA Structure

Answer 5

Double Helix

Question 6

The complementory bases

Answer 6

A-T/U (2 Hydrogen Bonds)
C-G (3 Hydrogen Bonds)

Question 7

RNA Structure

Answer 7

Ribose Sugar, Uracil instead of Thymine, single helix, generally shorter than DNA

Question 8

Compare DNA and RNA

Answer 8

Shape: DNA has a Double Helix, RNA is single stranded
Pentose Sugar: DNA has Deoxyribose, RNA has Ribose
Bases: DNA has A, T, C, G; RNA has A, U, C, G
Size: DNA is long, RNA is relatively short

Question 9

How DNA was discovered to be the carrier of the genetic code

Answer 9

First observed in 1800s, many doubted that is carried the genetic code because it was a relitively simple molecule
By 1953, experiments had shown that DNA was the carrier if the genetic code
In the same year, the double helix structure was discovered which helped it carry out its function
It was determined by James Watson and Francis Crick

Question 10

Why DNA replicates

Answer 10

For cell division

Question 11

Definition of semi-conservative

Answer 11

1/2 of the original DNA strands is conserved to make half of the new strand

Question 12

How DNA is replicated

Answer 12

page 57

Question 13

The action of DNA Polymerase

Answer 13

Only complimentory to 3’ end of DNA so can only add nucleotides to the 3’ end
This means the new strand is made 5’ to 3’

Because DNA is antiparallel, the DNA polymerase woring on one of the template strands moves in the opposite direction

Question 14

Evidence for semi-conservative replication

Answer 14

Meselson and Stahl’s Experiment
1. 2 samples of bacteria were grown for many generations - one in nutrient broth containing light nitrogen, the other in broth with heavy nitrogen. When they reproduced, the nitrogen helped make nucelotides for new DNA
2. A sample of DNA was taken from each bacteria, and spun in a cenrifuge. The DNA made from heavier N settled at the bottom and the light at the top
3. Then the bacteria in heavy N were placed in the light broth and left to reproduce for one generation and then spun in the centrifuge
4. The line formed in the middle

Question 15

What ATP stand for

Answer 15

Adenosine Triphosphate

Question 16

ATP Structure

Answer 16

Adenosine base, Ribose sugar, 3 Phosphate Groups

Question 17

How ATP releases energy

Answer 17

ATP + H2O -> ADP = Pi
(ATP Hydrolase catalyst + Energy Released)
The reverse happens to reform ATP by using energy and ATP Synthase catalyst

Question 18

Properties of Water

Answer 18

1. Metabolite- hydrolysis and condensation
2. Solvent- in the cytoplasm
3. High Latent Heat of Vaporisation- temperature control (cool down)
4. Cohesive- transport in plants
5. Specific Heat Capacity- takes lots of heat to change its state, temperature buffer

Question 19

Intermolecular forces between water molecules

Answer 19

Hydrogen Bonding

Question 20

Fe 2+ Uses

Answer 20

Haem Group in Haemoglobin

Question 21

H+ Uses

Answer 21

pH for enzyme controlled reactions

Question 22

Na + Uses

Answer 22

Co-transport

Question 23

PO4 3- Uses

Answer 23

Phosphate Group in DNA, RNA, and ATP

Question 24

What bond forms between 2 monosaccharides?

Answer 24

Glycosidic