210-2 Bio exam 1
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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 - 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 - Theories of biomolecular origins: categories
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1) Earth-based biopoesis
2) Extraterrestrial Origins - Biopoesis on Earth
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primordial soup;
Miller-Urey expt: Ch4, NH3, H20, H2 --(uv/lightning)--> organic cmpds incl AAs - extraterrestrial origins - panspermia
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"Panspermia" hypothesis - life from the stars
Murchison meteorite w/ 92 diff AAs - Non-covalent bonds
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Ionic bonds
hydrogen bonds
hydrophobic interactions
can der Waals forces - Essential AAs
- 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
- tyrosine - neurotransmitters
- importance
- zwitterions
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molecule that carries + and - charge
predominates in aqueous solns - catalytically perfect
- enzymes that have kcat/Km ratios that allow reactions to proceed at diffusion-limited rates
- 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 - induced-fit > lock and key
- 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.
- the active site
- holds substrates in place by weak, noncovalent interactions
- 2 H2O2 --> 2 H2O + O2
- catalase
- 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 - 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 - if double amount of enzyme...
- double the reaction velocity
- 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) - E + S --> ES--> E + P
- E + S --> ES--> E + P
- Classification of Lipids (6)
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1) fatty acids
2) triacylglycerols
3) phospholipids
4) glycolipids
5) terpenes
6) steroids - 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 - unsaturated fatty acids
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w/ one or more double bonds
kink in tail prevents close packing
lower m.pt., more liquid - triacylglycerol
- 3 fatty acids + 1 glycerol (condensation rxn)