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25 Cards in this Set
- Front
- Back
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Where do the elements come from?
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1) thermonuclear reactions in stars
2) explosion of stars 3) by cosmic ray irradiation |
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stages of evolution
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1) chemical evolution: small molecs form biopolymers
2) Self-organization: biopolymers develop capacity for self-replication 3) biological evolution: primitive living cells generate sophisticated metabolic systems and eventually the ability to form multicellular organisms |
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Theories of biomolecular origins: categories
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1) Earth-based biopoesis
2) Extraterrestrial Origins |
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Biopoesis on Earth
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primordial soup;
Miller-Urey expt: Ch4, NH3, H20, H2 --(uv/lightning)--> organic cmpds incl AAs |
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extraterrestrial origins - panspermia
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"Panspermia" hypothesis - life from the stars
Murchison meteorite w/ 92 diff AAs |
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Non-covalent bonds
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Ionic bonds
hydrogen bonds hydrophobic interactions can der Waals forces |
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Essential AAs
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Arg, His, Iso, Leu, Lys, Met, Phe, Thr, Trp, Val
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Nonessential AAs
(can be synthesized) |
Ala, Asn, Asp, Cys, Gln, Glu, Gly, Pro, Ser, Tyr
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tyrosine - neurotransmitters
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importance
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zwitterions
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molecule that carries + and - charge
predominates in aqueous solns |
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catalytically perfect
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enzymes that have kcat/Km ratios that allow reactions to proceed at diffusion-limited rates
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kcat = turnover number
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catalase w/ highest turnover number, or kcat
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induced-fit > lock and key
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induced fit mimics transition state, so when substrate bonds to enzyme, it distorts the bond (so w/ high E), so less E needed to be added to break bond.
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the active site
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holds substrates in place by weak, noncovalent interactions
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2 H2O2 --> 2 H2O + O2
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catalase
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Diffusion-controlled limit
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10^8 GO 10^7 M-1.s-1
an enzyme can only work as fast as substrate can diffuse to it |
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properties of enzymes (4)
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1) increase rxn rate by lowering activation E
2) are not used up or changed 3) do not change equilibrium position, only change rate at which equil. attained 4)form a transietnt (noncovalent) complex w/ reactant, to stabilize transition state |
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if double amount of enzyme...
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double the reaction velocity
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at fixed conc. of nonallosteric enzyme, & substrate conc. change...
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hyperbolic curve
low conc S: first order w/ respect to S (if two diff S, second order overall) hi conc S: zero order w/ respect to S (if two diff S, pseudo-first order overall) |
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E + S --> ES--> E + P
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E + S --> ES--> E + P
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kcat = turnover number
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-the max # of S --> P by each active site
-measures how fast enzyme can catalyze a rxn -to get kcat, conc. of E must be known |
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Classification of Lipids (6)
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1) fatty acids
2) triacylglycerols 3) phospholipids 4) glycolipids 5) terpenes 6) steroids |
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saturated fatty acids
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no double bonds
packed closer more E needed to break interactions of fatty acids higher m. pt. more solid |
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unsaturated fatty acids
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w/ one or more double bonds
kink in tail prevents close packing lower m.pt., more liquid |
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triacylglycerol
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3 fatty acids + 1 glycerol (condensation rxn)
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