BCHM 4611 Exam 2 Questions &
Answers
What determines whether a reaction is spontaneous or not? - ANSWERSThe sign of the change
in free energy (ΔG) of the reaction
What determines the rate of the reaction? - ANSWERSThe magnitude of the activation energy
(ΔG‡)
The reaction coordinate for covalent catalysis has... - ANSWERSTwo peaks, with a trough in
between them where the stable intermediate is formed
In the chymotrypsin reaction, how is the tetrahedral intermediate stabilized? -
ANSWERSOxyanion hole stabilization through hydrogen bonding with H's on Ser195 and Gly193
Competitive inhibitor - ANSWERSCompetes with the substrate for binding at the enzyme's
active site; frequently resemble the substrate or product of a reaction
The best competitive inhibitors... - ANSWERSMimic the transition state of the reaction
Triacylglycerols (triglycerides) - ANSWERSA glycerol molecule esterified to three fatty acid
molecules; the most common form of fatty acid storage
Integral membrane proteins - ANSWERSHave hydrophobic peptide regions embedded in the
lipid bilayer and these proteins require strong detergents to isolate
, Peripheral membrane proteins - ANSWERSAssociate with the polar head groups of membrane
lipids or with the exposed regions of other membrane proteins; can be isolated with mild salt
solutions which will compete to bind with these regions
Lipid-linked proteins - ANSWERSInsert a hydrophobic anchor into the membrane
Types of lipid-linked proteins - ANSWERSMyristoylated, palmitoylated, prenylated, and GPI-
linked
Myristoylated protein - ANSWERSA myristoyl group (C14:0) attached to an N-term Gly via an
amide linkage
Palmitoylated protein - ANSWERSA palmitoyl group (C16:0) reversibly attached to a Cys side
chain via a thioester linkage
Prenylated protein - ANSWERSAn isoprenoid group linked to a C-term Cys via a thiother linkage
GPI-linked proteins - ANSWERSGPI group linked to the C-term of the protein
How do ion movements during an action potential affect membrane potential? - ANSWERSInflux
of Na+ causes depolarization (more positive membrane potential) which triggers opening of K+
channels to restore the resting potential (more negative)
Exocytosis - ANSWERSVesicles fuse with the plasma membrane, allowing substances to cross
the membrane without using transporters
Lipid hormones - ANSWERSMove inside the cell to activate intracellular receptors
Answers
What determines whether a reaction is spontaneous or not? - ANSWERSThe sign of the change
in free energy (ΔG) of the reaction
What determines the rate of the reaction? - ANSWERSThe magnitude of the activation energy
(ΔG‡)
The reaction coordinate for covalent catalysis has... - ANSWERSTwo peaks, with a trough in
between them where the stable intermediate is formed
In the chymotrypsin reaction, how is the tetrahedral intermediate stabilized? -
ANSWERSOxyanion hole stabilization through hydrogen bonding with H's on Ser195 and Gly193
Competitive inhibitor - ANSWERSCompetes with the substrate for binding at the enzyme's
active site; frequently resemble the substrate or product of a reaction
The best competitive inhibitors... - ANSWERSMimic the transition state of the reaction
Triacylglycerols (triglycerides) - ANSWERSA glycerol molecule esterified to three fatty acid
molecules; the most common form of fatty acid storage
Integral membrane proteins - ANSWERSHave hydrophobic peptide regions embedded in the
lipid bilayer and these proteins require strong detergents to isolate
, Peripheral membrane proteins - ANSWERSAssociate with the polar head groups of membrane
lipids or with the exposed regions of other membrane proteins; can be isolated with mild salt
solutions which will compete to bind with these regions
Lipid-linked proteins - ANSWERSInsert a hydrophobic anchor into the membrane
Types of lipid-linked proteins - ANSWERSMyristoylated, palmitoylated, prenylated, and GPI-
linked
Myristoylated protein - ANSWERSA myristoyl group (C14:0) attached to an N-term Gly via an
amide linkage
Palmitoylated protein - ANSWERSA palmitoyl group (C16:0) reversibly attached to a Cys side
chain via a thioester linkage
Prenylated protein - ANSWERSAn isoprenoid group linked to a C-term Cys via a thiother linkage
GPI-linked proteins - ANSWERSGPI group linked to the C-term of the protein
How do ion movements during an action potential affect membrane potential? - ANSWERSInflux
of Na+ causes depolarization (more positive membrane potential) which triggers opening of K+
channels to restore the resting potential (more negative)
Exocytosis - ANSWERSVesicles fuse with the plasma membrane, allowing substances to cross
the membrane without using transporters
Lipid hormones - ANSWERSMove inside the cell to activate intracellular receptors
