- Created by: ebcrankomills
- Created on: 28-05-19 15:02
- In photosynthesis, light provides the energy needed to build organic molecules such as glucose.
- This energy can be used to form chemical bonds within ATP, it is the breaking of these bonds which releases energy used to form bonds as glucose is made.
- Glcuose and other organic molecules are broken down in respiration, the energy realeased from this is used in the syntehsis of ATP
- The ATP is then used in the cells to break bonds in metabnollic reactions.
Energy (sun) ➡ ATP ➡ Large organic molecules (glucose) ➡ ATP ➡ processes requiring energy
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- The ATP that is made in photosynthesis and respiration is usually synthesised by chemiosmosis.
- Chemiosmosis- involved the diffusion of protons fron a region of high concentration to a region of low concentration through a partially permeable membrane.
- As the protons flow down the cocnentration gradient, energy is released which is used to attach a phosphate (Pi) to ADP
- ADP + Pi ➡ ATP
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There are two ways in which electrons can be excited:
- Those present in pigment molecules can be excited by absorbing light from the sun. Chlorophyl is an example of one such pigment.
- High energy electrons are released when chemiocal bonds are broken in respiratory substrate molecules (glucose)
- The excited electrons pass into an electron transportchain and are then use to generate a proton gradient.
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Electron Transport Chain
- Consists of a series of electron carriers, each one has a progressively energy levels.
- As the high energy electrons move from carrier to carrier energy is released.
- The release of energy pumps protons across a membrane in turn creating a concentration gradient across the membrane, this is a proton gradient.
- The proton gradient is maintained due to the impermeability of the membrane to hydorgen ions.
- The only way that protons can move back through the membrane down their concentration gradient is through hydrophilic membrane channels that are linked to the enzyme ATP synthase.
- The flow of proons through these channels provides the energy required to synthesis ATP.
- In photosynthesis, ATP is used to synthesise glucose, the ATP produced in respiration provides the energy required by metabollic processes.
- Oxidative phosphorylation and photophosphorylation are also vital to chemiosmosis.
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