How is ATP used? - Cell can't get energy directly from GLUCOSE.
- In respiration: energy released from glucose is used to make ATP.
- Condensation betwee... [Show More] n Pi and ADP, using energy from energy-releasing reaction.
- ATP synthase catalyses.
- ATP diffuses to where energy is needed, hydrolysed here back into ADP and Pi, chemical energy released from phosphate bond and used - ATP HYDROLASE catalyses this.
ADP and Pi recycled, process again.
Properties of ATP - Stores or releases only SMALL amount of energy at a time, no energy wasted as heat.
- Easily broken down, energy can be released instantaneously.
- CAN BE quickly re-made.
- Can make other mol. more reactive by transferring one of phosphate groups (PHOSPHORYLATION)
- ATP can't pass out of cell, always immediate source of energy
Coenzymes - Molecule that aids function of an enzyme
- Transfer chemical group from one to another
- NADP in photosynthesis
TRANSFERS hydrogen from one to another, so can reduce and oxidise a molecule
Chloroplasts - Double membrane,
- Thylakoids stacked up, forming grana, linked together by LAMELLAE.
- Contain photosynthetic pigments, e.g. a, b, carotene.
- Coloured substances, absorb light energy.
Pigments found in thylakoid membranes - attached to proteins = PHOTOSYSTEM.
PHOTOSYSTEM I - absorbs light best at wavelength of 700, II - best at 680
- STROMA = enzymes, sugars, organic acids
- Carbohydrates produced aren't used straight away, stored as starch grains
Light-dependent reaction 1) THYLAKOID MEMBRANES
2) Light energy absorbed by PSII, chlorophyll.
3) Excites electrons in the chlorophyll, move to a higher energy level.
- Move down electron transport chain.
- Chlorophyll has been PHOTOIONISED>
4) As electrons leave, replaced. Light energy splits water into H+ ions, electrons and oxygen - photolysis.
- H2O = 2H+ + 1/2O2
5) Electrons lose energy as they move donw the transport chain, this is used to transport protons into THYLAKOID, higher conc. than stroma.
- PROTON gradient, protons move down, via ATP SYNTHASE, in thylakoid membrane. THIS energy is used to combine ADP and Pi = ATP
5) Electrons transferred to NADP and H+ from stroma, forming REDUCED NADP
- chemiosmosis [Show Less]
