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2.1 Energy and ATP
All living organisms need energy to survive, from the sun
Plants use energy from the sun and convert it to chemical energy but
Plants and animals break down organic molecules to adenosine triphosphate (ATP)
Energy is the "ability to work"

AQA Biology A2 Notes

Page 2

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Variety of forms, light, heat, sound, electrical, magnetic, mechanical,
chemical, and atomic energy
Changed to one form of another
Cannot be created for destroyed
Measured in joules
Living organisms are ordered systems that require energy to stop them becoming
Metabolism, all reactions that take place in organisms involve energy…

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Active transport, ions and molecules against a concentration gradient across
plasma membranes
Maintenance, repair and division, cells and organelles within cell
Production of substances, within organisms, enzymes and hormones
Maintenance of body temperature, birds, mammals. Organisms are
endothermic need energy to replace energy lost as heat
Flow of energy through…

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Chemical energy from photosynthesis in the form of organic molecules
converted into ATP during respiration in the cells
ATP is used by cells to perform useful jobs
Adenosine triphosphate (ATP) has three phosphate groups.
Key to how it stores energy
Bond between groups are unstable, have low activation energy, easily…

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Conversion of ATP to ADP is reliable reaction therefore energy can be used to add
inorganic phosphate to ADP and re-form ATP
Water is removed in this reaction, condensation reaction
Synthesis of ATP from ADP involves addition of phosphate
Photophosphorylation, takes place in the chlorophyll-containing plants during
Oxidative phosphorylation,…

Page 6

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ATP is synthesised using energy released during transfer of electrons along a chain
of electron carrier molecules either in chloroplasts or the mitochondria
ATP makes a good donor, instable phosphate bonds not good long term fat store
ATP is immidate source of energy cells don't store large amounts of ATP…

Page 7

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Hydrolysis if ATP is single reaction, releases immediate energy. Glucose is long
series of reactions
ATP cannot be stored, continuously made with cells that need it
ATP is energy source for;
Metabolic process, build macromolecules from basic moles
Polysaccharide from monosaccharides
Polypeptide from amino acids
DNA/RNA from nucleotides
Movement, ATP…

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Secretion, needed to form lysosomes necessary for secretion of cell
Activation of molecules, phosphate molecule transferred from ATP to
another makes it more reactive lowers activation energy. ATP allows enzyme
reactions to occur readily

AQA Biology A2 Notes


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