4- DNA, RNA and ATP

Question 1

Structure of Nucleotide?

Answer 1

• Pentose sugar (DNA = deoxyribose/ RNA = Ribose)
• Phosphate group
• Nitrogen Base (DNA bases = Adenine, Thymine, Cytosine and Guanine/ RNA bases = Adenine, Uracil, Cytosine and Guanine)

Question 2

Base Bonding rule?

Answer 2

DNA –> Adenine + Thymine and Cytosine + Guanine

RNA –> Adenine + Uracil and Cytosine + Guanine

Question 3

Purine Bases?

Answer 3

Adenine + Guanine

Question 4

Pyrimidine Bases?

Answer 4

Cytosine, Thymine and Uracil

Question 5

DNA/RNA polymerisation?

Answer 5

Condensation reaction between nucleotides forming phosphodiester bonds. Sugar phosphate backbone

Question 6

DNA structure?

Answer 6

Complimentary base pairing
A --> T 2 H-bonds
C --> G 3 H-bonds
Double stranded
Anti-parallel, prime strand 5' to 3' and other side 3' to 5'

Question 7

What is conservative DNA replication?

Answer 7

The original strand remains as it was and the new strand is made that is identical

Question 8

What is semi-conservative replication?

Answer 8

Each strand acts as a template and the daughter DNA has one original strand and one new strand

Question 9

Difference between RNA and DNA?

Answer 9

RNA pentose sugar is Ribose
RNA is single stranded
RNA has the Uracil nucleotide where the DNA thymine would be

Question 10

What is DNA replication?

Answer 10

Semi-Conservative

Question 11

Semi-conservative replication of DNA (process)?

Answer 11

• DNA helicase unzips the DNA double helix
• Hydrogen bonds broken
• Each strand acts as template
• Free nucleotides bind to their complimentary bases and form hydrogen bonds using base pairing rule
• DNA polymerase joins the two new lines of nucleotides together and zips them back up - hydrogen bonds re-form

Question 12

Structure of ATP

Answer 12

Ribose
Adenine
3 Phosphate groups

Question 13

What is the use of ATP

Answer 13

‘Energy currency’ of cells
Energy released from glucose during respiration is used to make ATP
Energy stored in high energy bonds between the phosphate groups

Question 14

How is energy created from ATP?

Answer 14

Energy released when a hydrolysis reaction breaks down ATP into ADP and one phosphate group. This is catalysed by ATP hydrolase

Question 15

How is ATP resynthesised?

Answer 15

ADP and phosphate re-joined using ATP synthase

Question 16

Inorganic ions

Answer 16

Ion - an atom which has an electric charge
Cation - positive
Anion - negative
inorganic ion - doesn’t contain carbon

Question 17

Iron ion

Answer 17

Important part of haemoglobin

• Large protein that carries oxygen in the red blood cells
• four polypeptide chains, each with an iron ion, Fe2+, in the centre
• Iron ion binds to the oxygen in haemoglobin
• When oxygen is bound Fe2+ becomes Fe3+ temporarily until oxygen is released

Question 18

Hydrogen ions

Answer 18

Determine pH - the more H+ the lower the pH

Question 19

Sodium ions

Answer 19

Help transport Glucose and Amino Acids across membranes

- co-transport innit

Question 20

Phosphate ions

Answer 20

Phosphate groups on DNA, RNA and ATP
Bonds between phosphate groups on ATP store its energy
Phospate groups in DNA and RNA allow nucleotides to join together to form polynucleotides

Question 21

Melselson and Stahl’s experiment?

Answer 21

To validate semi-conservative replication
Using Heavy Nitrogen (15) and light Nitrogen (14) isotopes
Bacteria grown in broth, one community in heavy and one in light - took up nitrogen into their DNA
When centrifuged the Heavy nitrogen settled lower than the lighter one
The bacteria grown in the heavy broth were placed in light nitrogen for one round of DNA replication
After centrifugation the new DNA settled in the middle as it was half heavy and half light - semi-conservative
If it was conservative it would be two separate bands, one high and one low