Biology 172 Lecture 6
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Biology 172 Lecture 6
Biology 172 Lecture exam review
Biology 172 Lecture 6 exam review
Less enzyme results in a ....
lower Vmax (fewer products in a given time) (fewer active sites)
Rate of reaction increases as ...
increase [S] to a maximum rate (velocity, Vmax)
Temperature will affect the ____ _____ of the substrates
inhibitor binds to enzyme by
, conformation is altered
e.g nerve gas
Competitive inhibition directly ...
blocks the active site
Compete with S for active site of enzyme Often resemble S
Bind to enzyme with weaker bonds
Some antibiotics, anticancer drugs, herbicides, pesticides To design the inhibitor must
have knowledge of active site / "S" structure
Molecule binds away from active site and alters active site function
NOT overcome by changes in substrate concentration (i.e Vmax will be LOWER)
Reversible and non-reversible (covalent modification enzyme)
Allosteric regulation occurs when ...
a regulatory molecule binds away from the active site.
Allo = dteric =
An Enzyme's Activity is ..
Enzymes are limited in their catalytic flexibility by the chemistry provided by ....
the R-group of amino acids. For example, none of the R-groups can absorb visible light, or bind oxygen (O2) as a carrier.
Cofactors and Coenzymes are additional ...
non-protein factors that can work with protein to provide a
broader range of chemistries at active sites
, allowing enzymes to catalyze a
wider range of reactions
Cofactors are ...
small non-protein molecules required for an enzyme to function normally.
Usually inorganic (metal) ions
Coenzymes are ...
: NAD, CoA, vitamins
Derived form vitamins - hence the dietary requirement
Provide enzymes with a broader range of catalytic reactions
Most drugs are ...
Most of the rest are non-competitive inhibitors
The mevalonate pathway ...
synthesizes cholesterol and many other metabolites
reductase is an
the first step in the pathway
HMG-CoA reductase uses HMG-CoA as a substrate
Decreases blood cholesterol.
Its mechanism of action is to inhibit cellular synthesis of cholesterol.
When cellular synthesis of cholesterol is decreased with Lipitor, cells respond by taking up cholestrol from the blood
Lipitor, Zocor, Crestor, Pravachol are all competitive inhibitors of HMG-CoA reductase
Reverse transcriptase is a key enzyme for HIV replication
Multiple AIDS drug target this enzyme for inhibition
competitive inhibitor, binds at active site
non-competitive inhibitor, binds adjacent to active site
4 groups of Lipids
Mostly composed of
Fuel storage, membranes, hormones
Very diverse class of biological molecules. Waves, some pigments, vit A, vit D, cholesterol
Store a LOT of energy - so release a lot of energy when broken down
Hydrocarbon chains with terminal carboxyl group
(no double bonds) or
(with double bonds)
Not water soluble
Double-bonds in fatty acids determines ______
no double-bonds in hydrocarbon chain
solid at room temperature
double-bonds in hydrocarbon chain
liquid or oil = more fluid
glycerol linked by ester linkages to 3 acids
condensation (dehydration) reaction
Triacylglycerol = fats
like triacylglycerides, but phosphate-containing compound replaces one fatty acid
Have polar part (hydrophilic hear) and a non-polar part (hydrophobic tail)
major component of membranes / make membranes
both hydrophilic and hydrophobic regions
2 ways to transport across membranes
provide permeability barriers for the cell
composed of lipid bilayer (mostly phospholipids)
What affect membrane permeability
Length and degree of saturation of the phospholipid tails
Membranes possess a fluid quality
Phospholipids "drift" within
side of the bilayer
Fluidity and permeability is enhanced by unsaturated fatty acid tails
cholesterol (a steroid) stabilizes the membrane
Stabilizes membranes by interacting with fatty acid tails of phospholipids
Membranes vary in composition
From one species to another
From one organelle type to another
Phospholipids are different on each side of the bilayer
Proteins are different on each side of the bilayer
Different inside and outside faces
Different lipids in the bilayer and different proteins on the cytoplasmic and extracellular sides of the membrane
Outside layer of the vesicle becomes ...
cytoplasmic side when it fuses
Inside face of ER/ Golgi becomes ...
outside (extracellular) face of plasma membrane