2.Nucelic Acids

Question 1

Facts about ribonucleic acid (RNA)

Answer 1

Single short strand
Ribose sugar
A G C U
Three forms-messenger transfer and r

Question 2

Facts about deoxyribonucleic acids (DNA)

Answer 2

Double long strand
Deoxyribose
A C G T

Question 3

What’s the structure of a nucleotide

What’s the reaction that forms them and what’s the bond formed

Answer 3

Phosphate group, pentose sugar, organic base

Condensation reaction
Phosphodiester bond between carbon 3 and phosphate of next nucleotide
Chain is called polynucleotide

Question 4

Facts about base pairing

Answer 4

Bases of DNA attach to eachother by hydrogen bonds
Complementary base pairing
C-G has 3 hydrogen bonds, the more c-g bonds the stronger and more stable

Question 5

What increases the stability of DNA

Answer 5

Phosphodiester sugar backbone protects the chemically reactive organic bases

Hydrogen bonds when numerous are strong

Question 6

What’s the function of dna

Answer 6

Responsible for passing on genetic information cell to cell

Many variations in base sequences = genetic variation of species/organisms

Question 7

How is DNA suited to its function

Answer 7

Stable structure-rarely mutates
Hydrogen bonds-allow for replication and protein synthesis
Large molecule-lots of genetic information
Sugar Phosphate backbone-protects the organic bases
Base pairing-DNA can be replicated

Question 8

What are the two stages of DNA Replication

Answer 8

Nuclear division-nucleus divides

Cytokinesis-whole cell

Question 9

Process of semi conservative replication

Answer 9

1-enzyme DNA helicase causes two strands of dna to unwind by breaking jt ehydrogen bonds between the complimentary base pairs
2-each strand acts as a template for DNA replication
3-free activated nucleotides bind specifically to their complimentary base
4-DNA polymerase then catalysed the condensation reaction which forms the phosphodiester bonds between nucleotides. Forming a polynucleotide chain with a sugar phosphate backbone
5-Now two DNA molecules, each with an original strand and a newly synthesised strand

Question 10

Evidence for semi conservative dna replication

Answer 10

1-bacteria was grown in a median containing n14, this was incorporated into the dna bases
2-bacteria transferred to median containing n15 and then incorporated into half the dna
3-when our in centrifuge half the dna was lighter

N14 is lighter than N15 so it will separate out-

Question 11

What is energy

And when did it originally come from

Answer 11

Ability to do work

Originally from sun

Question 12

What’s ATP and what’s the reaction for it

Answer 12

Adenine triphosphate

ATP + H2O ——> ADP + energy

Question 13

What is ATP made of

Answer 13

Adenine
\
Ribose — phosphate — phosphate — phosphate

Question 14

How does ATP store energy

Answer 14

• The bonds between phosphates are unstable and have low activation aenergy
• easily broken
• when broken releases large amount of energy
• normally only terminal phosphate is removed

Question 15

Synthesis of ATP

Answer 15

Reversible reaction

ATP is hydrolysed by ATP hydrolase to for ADP and an inorganci phosphate

ADP is condestationed by ATP synthase which adds the iP to adp

Question 16

What is phosphorylation

Answer 16

The addition of a phosphate group to a molecule

Question 17

What are the 3 ways ATP is synthesised from ADP

Answer 17

1-photo phosphorylation-happens in chlorophyll containing plant cells during photosynthesis
2-oxidative phosphorylation-in plant and animal cells during respiration
3-substrate Keven phosphorylation-when phosphate groups are transferred from donor molecules to ADP in plant and animal cell

Question 18

What’s the role of ATP

Answer 18

Immediate energy source-cells don’t store it
Releases less energy-manageable
Single reaction-quick release

Question 19

Energy requiring processes that require ATP

Answer 19

Metabolic-energy to build up macromolecules
Movement-energy for muscle contraction
Active transport-Energy to change shape of carrier proteins
Secretion-needed to form lysosomes
Activation of molecules-inorganic phosphate used to phosphorylase other compounds

Question 20

Why is water dipolar

Answer 20

Oxygen has a stronger electrostatic pull, pulls the electrons closer to it, causing it to be slightly negatively charged

Subsequently hydrogen is left as slightly positively charged.

Water is dipolar as its poles are oppositely/separately charged

Question 21

What does the hydrogen bonding do between water molecules

Answer 21

Hydrogen bond forms between a slightly positive hydrogen and a slightly negative oxygen of another molecule

Helps stick the water molecules together

Question 22

What is specific heat capacity

Answer 22

Due to water being extensively hydrogen bonded
More heat energy is required to break the bonds
Therefore higher boiling point
Creates thermostable environment as vast amount of energy is needed to change the temperature

Question 23

What is latent heat of vapourisation

Answer 23

Hydrogen bonding of water molecules means it requires a lot of heat energy to evaporate 1g of water

Evaporation of a small volume of water creates a huge cooling effect

Question 24

What is cohesion and surface tension

Answer 24

Due to hydrogen bonding water has large cohesive forces that allow it to be pulled up a tube (xylem)

When water molecules meet air they are pulled into the body of after creating surface tension, surface tension is strong enough to hold small organisms

Question 25

Why is water a metabolite

Answer 25

Used to break down complex molecules (hydrolysis)
Used to form complex molecules (condensation)
Chemical reactions take place in it
Major raw material in photosynthesis

Question 26

Why is water a solvent

Answer 26

It readily dissolves substances eg

Gases
Wastes
Inorganic ions
Enzymes