Nucleic Acids

Question 1

What are individual nucleotides made up of

Answer 1

A Penrose sugar, a phosphate group
A nitrogen containing organic base - ATCG

Question 3

What reaction forms the 3 components of nuclei acids

Answer 3

Condensation

Question 4

What is the bond between 2 nucleotides called

Answer 4

Phosphodiester

Question 5

What is rna

Answer 5

A polymer made up of nucleotides

Question 6

What is the structure of RNA

Answer 6

Short Single stranded
Penrose sugar is always ribose
AUCG
Generally shorter

Question 7

What are ribosomes made up of

Answer 7

RNA and proteins

Question 8

DNA structure

Answer 8

Pentode sugar is deoxyribose
Organic bases are ATCG
Each of the 2 strands is extremely long, joined together by hydrogen bonds
Double stranded

Question 9

What forms the structural backbone of the DNA molecule

Answer 9

Phosphate and deoxyribose

Question 10

Why is DNA a stable molecule

Answer 10

The phosphodiester backbone protects the more chemically reactive organic bases inside the double helix
Hydrogen bonds link the organic base pairs forming bridges between the phosphodiester uprights
Other interactive forces between the base pairs hold the molecule together

Question 11

What needs to happen before a nucleus divides

Answer 11

DNA replication to ensure all daughter cells have the genetic information

Question 12

What 4 requirements are needed for semi conservative replication to take place

Answer 12

4 types of nucleotide - ATCG
Both strands of the dna molecule act as a template for the attachment of these nucleotides
The enzyme DNA Polymerase
A source of chemical energy is required

Question 13

What is the process of semi- conservative replication

Answer 13

Enzyme DNA helices breaks the hydrogen bonds linking the base pairs of DNA
As a result the double helix separates into its 2 strands and unwinds
Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing
Nucleotides are joined together in a condensation reactions by the enzyme DNA polymerase which makes phosphodiester bonds to form the missing polynucleotide strand on each of the 2 original polynucleotide strands of DNA

Question 14

What happens as a result of semi - conservative DNA replication

Answer 14

Each of the new DNA molecules contains one of the original DNA strands , that is , half the originalDNA has been saved and built into each of the new DNA molecules

Question 16

First step of the M-S experiment

Answer 16

Bacteria were initially grown in a medium containing the heavy isotope N15 ensured that all bacterial dna incorporated the heavier isotope into its structure

Question 17

2nd step MS ex

Answer 17

Bacteria was transferred to a medium containing the lighter isotope N14 allowing researchers to observe how DNA changed over successive rounds of replication

Question 18

3rd step

Answer 18

After each generation DNA was extracted and analysed using centrifugation , separating molecules based on density

Question 19

What happened after 1 and then 2 rounds of replication in the experiment

Answer 19

1 round, the DNA formed a single light band ruling out the conservative model of replication
2 round 2 bands were observed one intermediate and one light which supported the semi- conservative replication

Question 20

3 parts of ATP and explain each

Answer 20

Adenine - nitrogen- containing organic base
Ribose - Pentose sugar
Phosphates - chain of 3 phosphate groups

Question 21

How does ATP store energy

Answer 21

Bonds between the 3 phosphate groups are unstable and have a LOW ACTIVATION ENERGY - so are easily broken
When they do break they release a considerable amount of energy

Question 22

What is a hydrolysis reaction and what enzyme catalyses it

Answer 22

Water converts ATP to ADP , enzyme ATP hydrolase

Question 23

What type of reaction is the conversion of ATP to ADP what does this allow

Answer 23

Reversible and therefore energy can be used to add an inorganic phosphate to ADP to re form ATP
And is a condensation reaction as water is removed in the process

Question 24

What enzyme catalyses the reformation of ATP

Answer 24

ATP synthase

Question 26

The synthesis of ATP from ADP involves the addition of a phosphate molecule to ADP Occurs in 3 ways

Answer 26

In chlorophyll containing plants during photosynthesis In plant and animal cells during respiration

Question 27

Why is ATP a better immediate source of energy rather than glucose

Answer 27

Each ATP molecule releases less energy than each glucose molecule The energy for each reaction is therefore released in smaller more manageable quantities rather than the much greater quantities from glucose The hydrolysis of ATP to ADP is a single reaction that releases immediate energy Breakdown of glucose is a long series of reactions and therefore the energy release takes longer

Question 28

Why is a water molecule described as dipolar

Answer 28

Oxygen atom has a slight negative charge Hydrogen atoms have a slight positive charge

Question 29

3 features of water

Answer 29

High specific heat capacity Latent heat of vapourisation Cohesion and surface tension

Question 30

What is the importance of water to living organisms

Answer 30

Water in metabolism - hydrolysis and condensation reactions Water as a solvent - readily dissolves substances