AP Bio Unit 3 Review

1. Enzyme Structure and Catalysis

   • Enzymes are proteins that speed up reactions by lowering activation energy.

   • Active sites bind substrates; specificity (the fact that enzymes are specific to their substrates) is key.

   • Factors affecting enzyme activity: temperature, pH, and substrate concentration.

   • High temperature - disrupts interactions b/t amino acids which can denature the enzyme which makes it lose secondary and tertiary structure

2. Environmental Impacts on Enzyme Function

   • Temperature and pH can denature enzymes, altering their shape and function.

   • Inhibitors (competitive and non-competitive) can decrease enzyme activity.

   • Competitive inhibitors bind to the active site which compete with substrates

   • Noncompetitive inhibitors bind to an allosteric site which changes the active site

   • Regulatory molecules - Enzyme activity may be turned "up" or "down" by activator and inhibitor molecules that bind specifically to the enzyme.

   • Cofactors - Many enzymes are only active when bound to non-protein helper molecules known as cofactors.

   • Compartmentalization - Storing enzymes in specific compartments can keep them from doing damage or provide the right conditions for activity.

   • Feedback inhibition - Key metabolic enzymes are often inhibited by the end product of the pathway they control (prevents too much product from being made)

   • Cooperativity - When a substrate serves as an allosteric activator (binds to one site which increases activity of other sites)

   • Compartmentalization - Enzymes are stored in a specific part of the cell to do their job

   • Vmax means maximum velocity (rate of reaction)

     

   • Proteolytic enzymes - enzymes that break down proteins

3. Cellular Energy

   • ATP (adenosine triphosphate) is the primary energy carrier in cells.

   • Energy is released when ATP is hydrolyzed to ADP and inorganic phosphate.

   • First Law of Thermodynamics - energy cannot be created nor destroyed, only change form or transferred

   • Second Law of Thermodynamics - in every energy conversion some amount of useful energy is converted to unusable energy (commonly heat)

   • Transfer of heat increases entropy of the environment

   • Entropy - the measure of a system's thermal energy per unit temperature that is unavailable for doing useful work

   • Structure of ATP

     

   • Phosphate group - A functional group characterized by a phosphorus atom bonded to four oxygen atoms

   • ATP Hydrolysis Reaction - ATP + H2O ←→ ADP + Pi + energy (Pi is inorganic phosphate group, and ATP regeneration is the opposite)

   • Reaction coupling - Energetically favorable reaction (ATP hydrolysis) is directly linked with an energetically unfavorable reaction (endergonic)

     • Shared intermediate - product of one reaction is “picked up“ and used as a reactant in a second reaction

   • Anabolic - building up complex molecule

   • Catabolic - breaking down complex molecule

4. Photosynthesis

   • Occurs in chloroplasts; converts light energy into chemical energy (glucose).

   • Two stages: Light-dependent reactions (thylakoids) and Calvin cycle (stroma).

5. Cellular Respiration

   • Process of breaking down glucose to produce ATP.

   • Stages: Glycolysis (cytoplasm), Krebs cycle (mitochondria), and Electron Transport Chain (mitochondria).

6. Fitness

   • Relates to how efficiently organisms convert energy for growth, reproduction, and survival.

   • Metabolic rates and energy expenditure are key factors in fitness.

Summary

Understand enzyme function, energy transformations, and the processes of photosynthesis and respiration for cellular energetics.