What does DNA and RNA stand for
Deoxyribonucleic acid and ribonucleic acid
Name all the bases found in DNA
Cytosine
Guanine
Thymine
Adenine
Name all the bases found in RNA
Cytosine
Guanine
Uracil
Adenine
Name the constituent elements of a nucleotide in DNA
Nitrogenous base
Deoxyribose sugar
Phosphate Group
How are the elements of a nucleotide bonded
Via a condensation reaction
Name the bond and the reaction between two nucleotides
Phosphodiester bond and a condensation reaction
Describe the structure of DNA
Two polynucleotide chains in a double helix with bases facing the centre, complementary bases bonded by hydrogen bonds.
Why is DNA a stable molecule
- The phosphodiester backbone protects the more chemically reactive organic bases inside
- Hydrogen bonds form across complementary bases. If there is a higher proportion of C and G bases the DNA is more stable as C and G form 3 hydrogen bonds.
How is DNA adapted to carry out its function
- stable molecule so can pass from generation to generation without significant change.
- two separate strands are joined only with hydrogen bonds which allow them to seperate during DNA replication + protein synthesis
- It is a large molecule and therefore carries alot of genetic information
- Genetic material (bases) are protected by deoxyribose-phosphate backbone.
- Complementary bases means a DNA strand can be used as template for replication and transcription
Describe and explain the evidence for semi-conservative replication
- Two sample of bacteria growth in growth mediums, one containing N14 and one N15
- Sample of DNA from each batch was put into centrifuge and spun, heavier DNA is denser and settled lower in the centrifuge tube
- When bacteria from the N15 medium was removed and added to a N14 medium it was left for one round of DNA replication.
- If conservative replication old N15 DNA would settle at the bottom and N14 DNA would settle at the top
- If semi-conservative replication the DNA would have a old N15 strand and a new N14 strand meaning it would settle in the middle of the test tube
Name the constituent elements of ATP
- Adenine
- Ribose
- Phosphates
How does ATP store energy
The bonds between the phosphate groups are unstable and so have a low activation energy so are easily broken. When they break they release energy
What is the type of reaction and enzyme that turns ATP to ADP
- ATP hydrolase
- hydrolysis
What is the type of reaction and enzyme that turns ADP to ATP
- ATP synthase
- condensation reaction
Name three ways ATP is converted in ADP
- photophosphorylation (photosynthesis) [p]
- oxidative phosphorylation (respiration) [p and a]
- substrate-level phosphorylation [p and a]
Why is ATP a better immediate source of energy compared to glucose
- ATP releases less energy in more manageable quantities (reduces heat loss)
- Hydrolysis of ATP to ADP is a single reaction for immediate energy (glucose requires a series of reactions)
Name 5 processes ATP is required for
- metabolic processes (synthesising biological molecules)
- muscle contraction
- active transport
- secretion (form lysosomes for secretion of cell products)
- activation of molecules (Pi from hydrolysis of ATP can be used to lower activation energy of molecules eg glycolysis)
Why is water dipolar
Oxygen atom has slight negative charge while hydrogens have slight positive
What bonding does water show
Hydrogen bonds (+van der Waals)
Why are hydrogen bonds important in water
Water would be a gas at room temperature without them
Does water have a high or low SHC
High due to hydrogen bonds meaning water is a good buffer against sudden temperature changes
Does water have a high latent heat of vaporisation
High due to hydrogen bonds meaning evaporation of water in sweat is very effective (takes heat energy)
What is cohesion and what is its importance
- The tendency of molecules to stick together (due to hydrogen bonding)
- Water can be pulled up a xylem and water tension means some animals can walk across it
Name uses of water in living organisms
- Metabolism (hydrolysis reactions and is used in photosynthesis)
- Solvent in which metabolic reactions occur
- Cools organisms
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1. Biological Molecules75
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2. Nucleic Acids26
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3. Cells57
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4.Transport across cell membranes37
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5.Cell recognition and the immune system53
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6.Exchange between organisms and their environment73
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7.Mass transport93
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8.DNA genes and protein34
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9.Genetic diversity and adaptation30
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10.Biodiversity22
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12. Respiration60
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14. Response to stimuli52
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15.Nervous Coordination and Muscles77
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17. Inherited Change11
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20. Gene Expression106
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16. Homeostasis69
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Classification14
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11. Photosynthesis52
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F. Transpiration13
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F. Kidney and the control of water balence63
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F. Cell cycle and cancer28
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F. Enzymes digestion and absorption61
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F. Yr 13 cancer33
