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210-2 Bio exam 1


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Where do the elements come from?
1) thermonuclear reactions in stars

2) explosion of stars

3) by cosmic ray irradiation
stages of evolution
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
1) Earth-based biopoesis

2) Extraterrestrial Origins
Biopoesis on Earth
primordial soup;
Miller-Urey expt: Ch4, NH3, H20, H2 --(uv/lightning)--> organic cmpds incl AAs
extraterrestrial origins - panspermia
"Panspermia" hypothesis - life from the stars

Murchison meteorite w/ 92 diff AAs
Non-covalent bonds
Ionic bonds
hydrogen bonds
hydrophobic interactions
can der Waals forces
Essential AAs
Arg, His, Iso, Leu, Lys, Met, Phe, Thr, Trp, Val
Nonessential AAs
(can be synthesized)
Ala, Asn, Asp, Cys, Gln, Glu, Gly, Pro, Ser, Tyr
tyrosine - neurotransmitters
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
-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
Diffusion-controlled limit
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)
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...
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)
1) fatty acids
2) triacylglycerols
3) phospholipids
4) glycolipids
5) terpenes
6) steroids
saturated fatty acids
no double bonds
packed closer
more E needed to break interactions of fatty acids
higher m. pt.
more solid
unsaturated fatty acids
w/ one or more double bonds
kink in tail prevents close packing
lower, more liquid
3 fatty acids + 1 glycerol (condensation rxn)

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