Download AP Biology – PowerPoint Notes - Chapter 6

 AP Biology – PowerPoint Notes ‐ Chapter 6 ‐ Metabolism: Energy and Enzymes Definitions •
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Energy: the capacity to do work. Kinetic Energy: energy of motion Potential Energy: stored energy Chemical Energy: interactions of atoms, one to another, in a molecule. Laws of Thermodynamics •
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Energy cannot be created nor destroyed Energy can be changed from one form to another but there is always a loss of usable energy. Entropy •
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The universe spontaneously is moving toward entropy or randomness. All organisms require a constant input of usable energy to maintain their organization. Ecosystem and the 2nd Law of Thermodynamics •
Energy from the sun fuels all life processes on Earth. Metabolic Reactions and Energy Transformations Coupled Reactions: the breakdown of ATP, which releases energy, can be coupled to reactions that require an input of energy. •
ATP goes through a cycle: energy from glucose breakdown drives ATP buildup and then ATP breakdown provides energy for cellular work. o Endergonic ‐ absorbing energy o Exergonic – releasing energy Metabolic Pathways and Enzymes •
Cells have metabolic pathways in which every reaction has a specific enzyme Energy of Activation •
Minimum energy required to start a chemical reaction. Enzyme Action: •
Enzymes speed reactions because they have an active site where a specific reaction occurs. Factors Influencing Enzyme Activity •
Environmental factors like temperature and pH affect the activity of enzymes. Factors Affecting Enzymatic Speed •
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Substrate Concentration Temperature and pH o Denaturing Enzyme Concentration Enzyme Inhibition o Allosteric Site o Feedback Inhibition Enzyme cofactors o Cofactors o Coenzymes o Vitamins Substrate Concentration •
The more substrate, the more enzyme activity, the more products Temperature and pH •
Denaturing Enzyme Concentration Phosphorylation – addition of a phosphate group to a protein or other organic molecule ‐
Activates or deactivates enzymes Enzyme Inhibition •
Allosteric Site ‐ site on enzyme other than the active site o Feedback Inhibition Enzyme Cofactors •
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Cofactors – non‐protein component of enzymes Coenzymes – organic cofactor Small molecules (compared to protein part of enzyme) which make up part of active site. Without the coenzyme, the enzyme will not function (many are derived from VITAMINS) Vitamin Coenzyme Niacin Nicotinamide adenine dinucleotide (NAD+) Oxidation or hydrogen transfer Riboflavin Flavin adenine dinucleotide (FAD) Oxidation or hydrogen transfer Pantothenic acid Coenzyme A (CoA) Acetyl group carrier Vitamin B‐12 Coenzyme B‐12 Methyl group transfer Thiamin (B‐1) Thiaminpyro‐phosphate (TPP) Aldehyde group transfer Metabolic Pathways and Oxidation‐Reduction •
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Function Photosynthesis Respiration Electron Transport system ATP production o Chemiosmosis