BIOL 1000 Lecture 2: Midterm 2 Notes from textbook
15 Nov 2016
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Chapter 5 cell membranes & signalling: except 5. 7. Activation energy: initial energy investment to start reaction; energy barrier that exergonic reactions need to overcome to get to transition state (where bonds become unstable & ready to be broken); prevents them from proceeding rapidly. Enzymes: catalysts that greatly speed rate of spontaneous reactions because they lower activation energy; usually specific, so only speed reaction of single type of molecule; catalysts allows to reach ea without increasing temperature. Catalysis: occurs at active site (where enzyme binds to substrate reactant), then enzyme is released unchanged after reaction completion. Induced-fit hypothesis: unlike lock-and-key hypothesis, enzymes aren"t rigid and instead change their shape/confirmation to match substrate. Most enzymes need cofactor: nonprotein group that binds very precisely to enzyme, e. g. metal some cofactors are called coenzymes (organic molecules derived from vitamins) 4. 6 factors affecting enzyme activity: substrate concentration, competitive/non-competitive inhibitors, temperature & ph.
