1. Energy, Metabolism, and Enzymes Ch 6 Baboon Ch 5.1-5.8 Bat - Energy: the ability to do work - Two major types of energy 1. Kinetic - energy of motion - EX: movement, heat, electrical, radiant 2. Potential - stored energy - EX: positional, chemical bonds, gravitational, charge potential (battery) - Energy is constantly being transformed from one type to another - EX: radiant energy from sunlight transformed into the energy of chemical bonds (kinetic to potential)

2. 1st and 2nd Law of Thermodynamics - 1st Law - Law of Conservation of Energy - Energy can be transformed or transferred but it can't be created or destroyed - 2nd Law - Law of Entropy - When energy is is transformed or transferred, some will be "lost", usually as heat - Every change in Energy results in the world becoming more disordered (chaotic) - Entropy - the quantitative measure of disorder

4. Systems - Open - when energy and matter can be transferred back and forth between the system and its surroundings EX: human body - Closed - when energy and/or matter can NOT be transferred back and forthbetween the system and its surroundings

5. Energy of Life -Living organisms require a constant supply of energy to perform work that must take place in cells (powered by ATP) - Mechanical work - cell division, muscle contraction, cilia movement, etc... - Transport work - pumping substances across membranes - Chemical work - breaking and forming chemical bonds -Energy flows from the non-living world into living organisms and back - Conversion of Radiant Energy to Chemical Energy - Photosynthesis (makes glucose) - Chemical Energy is transferred between organisms - Energy is "lost" as heat along the way

6. Metabolism - Metabolism is the sum total of all chemical reactions in an organism (transformation of energy) - Two types of reactions- 1. Catabolic reactions release energy by breaking chemical bonds (complex ⇒ simple) - also known as exergonic reactions because they release energy - EX: Cellular respiration 2. Anabolic reactions use energy to make chemical bonds (simple ⇒ complex) - also known as endergonic reactions because they require energy - EX: Photosynthesis

8. Exergonic vs. Endergonic (Catabolic) (Anabolic) ΔG = amount of free energy in a system ΔG is negative, energy is given off ΔG is positive, energy is absorbed These reactions are usually coupled in living things - E released in exergonic is used to power endergonic

10. - Enzymes: proteins that act as catalysts for reactions without being permanently altered or destroyed - Catalyst: increases efficiency of reactions - Enzymes frequently have the suffix "ase" - Substrate: substance the enzyme acts on -EX: enzyme salivary amylase breaks down starch (substrate) in the food you eat -EX: enzyme glycogen synthase that builds glucose into glycogen Enzymes

11. - Enzyme - substrate relationships are specific -Active site - point where substrate and enzyme interact (bind) -Induced Fit Theory – active site is a crevice on the enzymes surface which interacts with the substrate. Enzyme folds around the substrate like a tight fitting glove Enzyme - Substrate Relationships

12. - Reversibility - enzymes can break substances down (catabolic) or help put them together (anabolic) Enzymes and Chemical Reactions

13. - Catabolic (exergonic) - Enzymes weaken bonds of substrate so less energy is needed to break it down - lowers activation energy - Anabolic (endergonic) - Enzymes chemically align angles of molecules to make bonding easier

14. Sucrose ----------------> Fructose + Glucose Substrates ----------------> Products (reactants) Enzyme (sucrase enzyme) Catabolic

15. - Activation energy: initial energy required to break chemical bonds during an exergonic (catabolic) reaction - i.e. Need to put a little E in before you can release some Enzymes and Chemical Reactions

16. - Enzymes act as catalysts - lower the activation energy required Exergonic rx

17. Environmental Conditions - Temperature - higher temperature result in increased molecular motion and higher kinetic energy. More collisions between molecules lead to faster reactions - in general an increase of 10°C doubles the rate of reactions - too much heat can, however, can cause denaturation

18. Environmental Conditions - pH - most enzymes require a neutral pH - Exceptions: - Pepsin (stomach) needs pH 2 - Trypsin (intestine) needs pH 7 - Concentration of substrate and product - Lots of substrate and little product = more product formed - Lots of product and little substrate = more substrate formed

19. - Non-protein molecules that are necessary for some enzymes to work - Usually vitamins that must be ingested by organisms because the body does not naturally produce them - EX: iron or zinc - Sometimes called co-enzymes Cofactors

20. Enzyme Inhibitors 1. Competitive inhibitors - molecule binds to the active site, preventing substrate from binding - usually reversible - EX: pesticides, drugs 2. Non-competitive inhibitors - molecule binds to a region other than the active site causing a shape change in the enzyme - EX: penicillin - prevents enzymes used by bacteria to assemble the cell wall from working

22. - Cooperativity - Enzyme becomes more receptive to substrate molecules once one substrate molecule has attached - EX: once one molecule of oxygen binds to hemoglobin it encourages the molecule to bind to several more molecules of oxygen Cooperativity

23. - Allosteric enzymes - enzymes have 2 kinds of binding sites 1. one site for the substrate (the active site) 2. one site called the allosteric site that allows the enzyme to be controlled - Allosteric inhibitors: bind to the allosteric site and stop the enzyme from functioning - Allosteric activators: bind to the allosteric site and turn the enzyme on. Allosteric Regulation