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25 Cards in this Set

  • Front
  • Back
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
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
catalase w/ highest turnover number, or kcat
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
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
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)