Nucleic Acids,Water And ATP

Question 1

Draw and label a DNA nucleotide

Answer 1

Question 2

Draw and label a RNA nucleotide

Answer 2

Question 3

Describe the structure of DNA

Answer 3

Double helix structure
Polymer of nucleotides
Each nucleotide consists of deoxyribose sugar, phosphate group and nitrogenous base
Phosphodiester bond between phosphate group of one DNA nucleotide and deoxyribose sugar of another DNA molecule
2 strands held by hydrogen bonds by complementary base pairs
Adenine forms 2 hydrogen bonds with thynine
Guanine forms 3 hydrogen bins with cytocine

Question 4

Structure of chromosomes

Answer 4

DNA associated with histone
Visible structure in mitosis which is presented as 2 identical sister chromatids

Question 5

Describe how the structure of DNA relates to its function

Answer 5

Sugar phosphate backbone so provides strength
Double stranded so act as templates
Weak hydrogen bonds which can be easily broken for replication
Many weak hydrogen bonds for strength and stability
Large molecule so stores alot of information
Complementary base pairs so accurate replication
Helical so compact
Base sequence codes for amino acids

Question 6

Describe semi Conservative replication

Answer 6

DNA helicase breaks hydrogen bonds and unwinds DNA double helix strands
Both strands act as an template
Free DNA nucleotides join to complementary base pairs by hydrogen bonds
Adenine to thymine
Cytocine to guanine
DNA polymerase joins adjacent DNA nucleotides by condensation reaction forming a phosphodiester bond
New DNA has one old strand and one new strand

Question 7

2 other theoretical models of DNA replication

Answer 7

Conservative model = an entirely new molecule made from DNA template
Dispersive model = new molecule made from segments of new and old DNA

Question 8

Who came up with the model

Answer 8

Crick and Watson

Question 9

Draw an ATP molecule

Answer 9

Question 10

Synthesis of ATP

Answer 10

Catalysed by ATP synthase
Produced in Photosynthesis and respiration
Condensation reaction
From ADP and pi

Question 11

Hydrolysis of ATP

Answer 11

Catalysed by ATP hydrolase
Hydrolysis reaction
Produces ADP and pi

Question 12

2 uses of ATP

Answer 12

Hydrolysis Provides energy for active transport,muscle contraction
Phosphorylation which the assication of a phosphate group and making substrate more reactive

Question 13

Describe why ATP is useful in biological

Answer 13

Releases energy instantaneously as little energy lost as heat
Can be rapidly re synthesised in one step
Is not lost from cells
Phosphorylation so makes compounds more reactive

Question 14

Explain the properties that make water important for organisms?

Answer 14

Metabolite in condensation and hydrolysis reaction
Solvent so allow transport of substances
High specific heat capacity so buffers changes in temperature which means takes alot of energy to heat up
High latent heat of vaporisation which provides a cooling effect
Cohesion so supports columns of water
Cohesion so produces surface tension and a habitat for aquatic organisms