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Energy for the Cell
What is ATP?Universal energy currency - large amount of free energy
ATP - adenosine triphosphate
ATP is made up of: adenine, ribose, 3 phosphate groups
Energy stored in phosphate bonds
ATP Hydrolysis - ATP breaks down to produce ADP, a phosphate group, and a large amount of energy
ADP - adenosine diphosphate
ATP Synthesis - combining of ADP with P - requires energy
What is ATP?
How is ATP Formed?ATP can be synthesized in two ways:
Substrate Level Phosphorylation
Oxidative Phosphorylation
Substrate-Level Phosphorylation - formation of ATP by direct transfer of a phosphate group from a substance to ADP
Enzyme catalyzed
Oxidative Phosphorylation - formation of ATP using energy transferred indirectly from a series of redox reactions
Involves final electron acceptor (oxygen - electronegative)
Food as FuelMolecules with lots of C-H bonds are high in energy
Potential energy stored in food molecules is released during oxidation reactions
Oxidation - loss of electrons (removal of H, addition of O)
Reduction - gain of electrons (removal of O, addition of H)
Energy released is transferred to energy carrying molecules
Energy CarriersNAD+ - positively charged coenzyme
- called nicotinamide adenine dinucleotide
- high energy electron carrier (oxidized form)
NADH - reduced form of NAD+
- carries potential energy to drive ATP synthesis
What is Cellular Respiration?
Both plants and animals use aerobic cellular respiration to extract energy from food when oxygen is present
Aerobic Cellular Respiration - process that uses oxygen to harvest energy from organic compounds
C6H12O6 + 6O2 -> 6CO2 + 6H20 + energy
Oxidation of glucose occurs through a series of enzyme catalyzed reactions
Occurs in cytoplasm and mitochondria of cells
Mitochondria generate most of the ATP used in eukaryotes
What is Cellular Respiration?
Two ways to extract energy from food in absence of oxygen:
Anaerobic Respiration - uses an inorganic substance other than oxygen as the final oxidizing agent to produce ATP
Fermentation - uses an organic compound as the final oxidizing agent to produce ATP
2 types: Alcohol Fermentation and Lactate Fermentation
Alcohol FermentationAlcohol Fermentation - glucose from food is converted into carbon dioxide, ethanol (alcohol), and ATP (energy)
C6H12O6 -> 2CO2 + 2C2H6O + energy
Example: bread making, brewing beer, wine
Lactate FermentationLactate Fermentation - glucose from food is converted into lactate and ATP (energy)
C6H12O6 -> 2C3H5O3 + energy
Example: yogurt, some cheeses, strenuous exercise
To Summarize3 pathways produce ATP: aerobic respiration, anaerobic respiration, and fermentation
Respiration pathways use electron transport systems to generate ATP by oxidative phosphorylation
Fermentation pathways lack electron transport systems