2.3 energy and ATP

Question 1

strutcure of ATP

Answer 1

1. adenine- nitrogen containing organic base
2. ribose- sugar molecule with 5 carbon ring structure which is backbone
3. phosphates - chain of 3 phosphate group

Question 2

ATP

Answer 2

adenosine triphosphate
nucleotide
main energy source to carry out processes within cells
nucleotide

Question 3

How ATP stores energy

Answer 3

bonds between 3 phosphates are unstable
- have low activation energy
- easily broken

when broken, release large amount of energy

Question 4

ATP equation

Answer 4

ATP + H2O -> ADP + Pi + E

adenosine triphosphate + water
->
adenosine diphosphate + inorganic phosphate + energy

Question 5

ATP to ADP

Answer 5

hydrolysis
catalysed by enzyme ATP hydrolase

Question 6

Synthesis of ATP

Answer 6

ATP to ADP is reversible reaction
- add inorganic phosphate to ADP to make ATP

catalysed by enzyme ATP synthase

water is removed in process- condensation reaction

Question 7

3 ways synthesis of ATP occurs

Answer 7

1. in chlorophyll- containing plant cells during photosynthesis (photophosphorylation)
2. in plant and and animal cells during respiration ( oxidative phosphorylation)
3. in plant and anima cells when phosphate groups are transferred from donor molecules to ADP (substrate-level phosphorylation)

Question 8

2 ways ATP is better immediate source energy than glucose

Answer 8

1. releases less energy so energy for reactions is released in smaller, more manageable quantities
2. hydrolysis of ATP to ADP is a single reaction that released immediate energy whereas breakdown of glucose is long series of reactions which takes longer to release energy

Question 9

5 things ATP is used for

Answer 9

1. metabolic processes- provides energy needed to build up macromolecules from basic units
2. movement- provides energy for filaments of muscle to slide past one another
3. active transport- provides energy to change shape of carrier proteins in plasma membrane
4. secretion- form lysosomes needed
5. activation of molecules- Pi released can be used to phosphorylate other compounds to make them more reactive, lowering activation energy in enzyme-catalysed reaction

Question 10

Why ATP is not good long-term energy storage

Answer 10

instability of phosphate bonds
cells only maintain few seconds supply
- is rapidly re-formed in mitochondria

Question 11

dipolar water molecule

Answer 11

oxygen atom has slightly negative charge, and hydrogen positive charge

hydrogen bonding occurs as opposite charge attract one another- cause molecules to stick together

Question 12

high specific heat capacity of water

Answer 12

hydrogen bonds cause h20 to have higher boiling point than expected
- takes more energy to overcome large amount of bonds

high shc

water acts as buffer against sudden temperature variations

Question 13

latent heat of vaporisation of waterf

Answer 13

takes large amount of energy to evaporate 1 gram of water

evaporation of water (e.g. sweat) in mammals is therefore effective means of cooling as body heat is used

Question 14

cohesion of water

Answer 14

tendency to stick together

has large cohesive forces
- allows it to be pulled up a tube e.g. xylem vessel

Question 15

surface tension of water

Answer 15

where h20 molecules meet air they are pulled back into the body of water rather than escaping

water surface acts like skin
- strong enough to support small organiss

Question 16

3 ways water is used in metabolism

Answer 16

1. breaks down complex molecules by hydrolysis. Is also produced in condensation reactions
2. chemical reactions take place in aqueous medium
3. major raw material in photosynthesis

Question 17

4 substances water readily dissolves in

Answer 17

1. gases e.g. O2 and CO2
2. wastes e.g. ammonia and urea
3. inorganic ions and small hydrophilic molecules e.g. amino acids, monosaccharides and ATP
4. enzymes, whose reactions take place in solution

Question 18

3 Important features of water

Answer 18

1. evaporation cools organisms and allows them to control temp
2. not easily compressed and provides support
3. transparent so aquatic plants can photosynthesis and light rays can penetrate jelly-like fluid that fills eyes and reach retina