clicker questions exam iii Flashcards
What is the difference between myoglobin and hemoglobin?
Myoglobin stores oxygen and hemoglobin transports it
The heme group, depending on the amino acid surrounding it, can bind:
Oxygen, co2, carbon monoxide
What is the p50 value of myoglobin
2.8 torr
What does the slope of the hill plot represent
cooperativity
What is the function of the protein surrounding the heme?
Modulates oxygen binding
Hemoglobin molecule contains how many Hemes?
4
What is the difference between the red and blue molecule shown?
Red- relaxed. r state, OXY
blue: constricted. t state, DEOXY
What is the structural reason for the bohr effect?
salt bridge which is lost in r state
Hydrogen binding at n term
Remembering the oxygen binding curves, a shift to the left represents?
Tighter binding of oxygen
How does BPG help in adapting hemoglobin to higher altitudes
Shifts the oxygen binding curve to the right
What is a structural reason for the BPG effect
binds to Beta hemoglobin
What effect does Boston mutation have on hemoglobin
Promotes methemoglobin formation
What is protein cooperativity?
How one binds compared to the next one binding.
How can cooperativity be measured?
Hill Equation
What happens to Ligand binding when there is a positive cooperativity
binding increases
What is the role of CA +2 in actin filament binding
binds to troponin, rotates, the actin so myosin head can bind to it
What causes the myosin power stroke?
Removing ADP
What is a similarity of myosin and kinesin movement
They both use ATP
They both move around
What is a difference between kinesin and myosin
Myosin comes in groups and is also actin. kinesin only has two heads that rotates and is microfilaments.
What is the role of an enzyme?
Speed up reaction
Specificity of an enzyme for a substrate is defined by
Active sites shape (amino acids), and complementary.
Define what a cofactor is
Another molecule that binds the protein and helps the reaction occur
In what way can enzymes be regulated?
Feedback inhibition
Allosteric regulation
What is DDGcat=/
Difference between activation energy with and without enzyme
What do enzymes change in the energy graph?
Activation energy
What stays the same in the energy graph?
Delta G, reactant amount
What is the main attribute of an acid/base mechanism?
Proton exchange
What defines a covalent bonding mechanism
Chemical bond that is heavy
Metal ions can act as what during an enzymatic mechanism
Charge stabilization
Ionization agent
Shielding agent
Define proximity effect
Organization of substrates, closer together will react
Define a Mechanism transition state
Intermediate??
Which catalytic mechanism is defined by proton movement
Acid base catalyst
Which of these counts for no more than 5X effect on rate
Proximity effect
Which type of catalyst can use iron
Metal ion aided catalyst
What type of mechanism does lysozyme use?
Acid base
Why does lysozyme use acid base?
Acid base is major, there is a movement of proton
What determines the substrate of serine type protease
Specificity pocket
What is affinity labeling?
Trojan horse effect, binds pocket and then binds nearby acid amino acid
What catalytic mechanism do serine protease use?
Covalent bond catalysis
What kind of mechanism could ATP hydrolysis be classified as?
Acid base catalysis
What kind of reaction could ATP phosphorylation be classified as
Covalent bond catalysis
What is the role of Mg ++ in these reaction
It’s stealing the charge, charge shielding
Kinetic data combined with ——- data allows the mechanism of a reaction to be determined
Structural
What is meant by order of a reaction
Number of molecules that must combine for reaction to occur
What is meant by the term half-life
Time it takes for half material to disappear
What order of reaction is half-life usually associated with
One
What does catalysis do to activation energy?
Lowers
The greater the delta G =/ the more —— the transition state is and the—— the reaction
Unstable, slower
How many fold is a reaction with DDG=/ cat of 17.13 kj/mol increased
1000
The following reaction 2A +B -> C represents which order of reaction
2
If an isotope has a half-life of 11 years, how many years have passed approximately 3.66% remains
55
What is the approximate k of an isotope if the half-life is 11 years?
.063/years
The determining step of a reaction with a stable intermediate, is the step with the:
a. Highest DeltaG
B. Smallest DG
C. Highest. DDG
D. Smallest DDG
Highest DG
What does DDG=/ represent
Change in activation energy
What is the main assumption of Michaelis-mentee eq.
Steady state
What is the difference between a equilibrium and steady state
Steady only forwards, equilibrium forward and backward.
What does Km represent?
Substrate concentration
What does Kcat/Km represent in enzymes
Catalytic efficiency
Why use lineWeaver- Burke instead of michaelis-menten
More accurate
When does enzymatic perfection occur?
When it is diffusion is limited.
Define random binding reactions
The order in which the substrate binding is random
Which type of competition has no change in Km
Noncompetitive
Which competition has the inhibitor binding at the substrate binding site
competitive
What is the effect of pH on an enzymes kinetics?
Change in Vmax and KM.
