Energy
Fill in the blank:
Higher free energy...
-____ stable
-____ concentrated
-____ ordered
-____ work capacity
Lower free energy...
-____ stable
-____ concentrated
-____ ordered
-____ work capacity
**objects tend to move from ___ free energy to ___ free energy!**
Lower free energy...
-___MORE_ stable
-__LESS__ concentrated
-_LESS___ ordered
-__LESSER__ work capacity
Higher free energy...
-__LESS__ stable
-__MORE__ concentrated
-__MORE__ ordered
-__GREATER__ work capacity
**objects tend to move from __HIGHER_ free energy to __LOWER_ free energy!**
What is the vmax?
-point of saturation
Nucleotide:
-a sugar (ribose = RNA; deoxyribose = DNA)
-a phosphate group
-a nitrogenous base (RNA? DNA?)
What is the difference between a phospholipid and a triacylglyceride? Why are they important?
phospholipid has a phosphate-containing compound that replaces 1 fatty acid
-important b/c phospholipids are a major component of biological membranes!
What is the chemical difference between reversible and irreversible inhibition?
reversible: non-covalent binding
irreversible: covalent binding
Explain the 1st and 2nd laws of thermodynamics
1st Law: energy is neither created nor destroyed, simply changes from one form to another
-ex: kinetic --> potential
2nd Law: the transformation of energy is associated with an INCREASE in disorder (aka entropy)
What is Km? What does a low Km mean? A high Km?
Km: "substrate concentration at which the reaction rate is half maximum (aka 1/2 vmax)"
-low Km: achieves maximum catalytic efficiency at a low substrate concentration (good, very efficient)
-high Km: takes a high substrate concentration to reach maximum catalytic efficiency (bad, not efficient)
What are the pyrimidine bases? Purine bases? Which bases pair with what (whose rule is this)?
pyrimidine: thymine, cytosine, uracil (one ring)
purine: adenine, guanine (2 rings)
-Chargaff's rule!
Differentiate between saturated vs. unsaturated fats
saturated: lack double bonds; SOLID at RT
-ex: butter
unsaturated: have double bonds; liquid at RT
-ex: oils
What is a catalyst? How does it work?
-catalysts do NOT affect delta G
-catalysts are NOT consumed in the reaction
-catalysts DO speed up the rate of the reaction!
exergonic: reactants have MORE energy than products; aka spontaneous; energy is RELEASED; delta G < 0
endergonic: reactants have LESS energy than products; aka non spontaneous; energy is ABSORBED; delta G > 0
What is a cofactor?
cofactor: small, non-protein molecules; typically inorganic (metal) ions
-ex: Zn+2, Mg+2
-cofactors work to provide a broader range of chemistry at the active site, which allows for enzymes to catalyze a broader range of reactions
Describe the sugar phosphate backbone
sugar phosphate backbone:
-has polarity
-5' phosphate end
-3' hydroxyl end
-next nucleotide added to chain is ALWAYS added to 3' OH end
Describe cholesterol. What kind of lipid is it?
cholesterol:
-largely hydrophobic, but has a polar head group (what is this called?)
-important component of animal membranes
-increases/decreases membrane fluidity depending on temperature
--> high T: decreases fluidity by reducing mobility of phospholipids
--> low T: increases fluidity by preventing tight packing of phospholipids
Explain the induced fit model for enzymes.
Enzyme catalysis = lock and key model, with the enzyme's active site representing the lock & the substrate representing the key
-enzyme structure is DYNAMIC!
-when substrate is bound to active site, the active site changes conformation to form an "induced fit", which allows TIGHTER binding between enzyme & substrate
How does protein synthesis occur (many AA --> more ordered, less stable protein)? (hint: what should delta G be)
endergonic reactions are coupled to exergonic reactions, which allows endergonic reactions to take place! need more negative delta G to overcome +G
How can Vmax be increased?
bonus: does this also increase Km? why or why not?
-this does NOT affect Km b/c it does not alter the enzyme's chemical characteristics, so you would expect the substrate to bind no better/worse than normal
What is the basic formula for a carbohydrate? What are the names of bond for each macromolecule?
basic carb formula = (CH2O)n
carbs = glycosidic linkage
lipids = ester linkage
proteins = peptide bond
NA = phosphodiester bond
put the following in terms of high to low membrane permeability:
O2, K+, glucose, glycerol
(high) O2, glycerol, glucose, K+ (low)
1) phosphodiester bonds
2) hydrogen bonds between bases
3) base stacking contributes to DNA stability
Explain the 2 classes of reversible enzyme inhibitors
1) competitive: "bear a close structural/chemical similarity to substrate"
-directly competes with substrate for access to enzyme's active site
-adding extra substrate CAN overcome competitive inhibitor
2) noncompetitive: "NOT similar to substrate"
-bind at location OTHER THAN the active site
-adding substrate CANNOT overcome inhibition (why?)
What are the 2 important functions of polysaccharides? provide an example of each. Also, are they alpha or beta polymers?
1) fuel storage (alpha)
ex: glycogen in animals; starch in plants
2) structural integrity (beta)
ex: cellulose in plants (cell walls), chitin (exoskeleton cell walls), peptidoglycan (bacterial cell walls)
Explain passive vs. active transport. Put the following into each category and explain:
-simple diffusion
-osmosis
-facilitated diffusion
-primary active transport
-secondary active transport
passive transport:
-simple diff
-osmosis
-facilitated diffusion
active:
-primary
-secondary
Vmax = same
Km = higher