Exam Three Flashcards
1
Q
What is required for enzymatic reactions?
A
Formation of an ES complex
2
Q
What is the equation for a first order reaction?
A
rate = k[A]
3
Q
What is the equation for a second order reaction?
A
rate = k[A][B]
4
Q
What order reaction occurs when the amount of substrate has no effect on the rate?
A
zero
5
Q
True or False: the higher the concentration of S, the faster the reaction
A
False, it is dependent on the amount of enzyme present
6
Q
True or False: the higher the concentration of E, the faster the reaction
A
True, although technically there is normally a limited amount of enzyme
7
Q
________ is an indicator of affinity for a substrate (binding efficiency)
A
Km
8
Q
Does a smaller or larger Km indicate better affinity?
A
smaller
9
Q
What is Vmax?
A
The maximum velocity the enzyme can achieve at a given enzyme concentration
10
Q
What is the kcat equation?
A
kcat = Vmax / total Enzyme concentration
11
Q
What value can be thought of as frequency of the reaction?
A
kcat
12
Q
what is the measure of both binding and catalytic events?
A
kcat/Km
13
Q
Does a larger or smaller value of kcat/Km indicate a better enzyme?
A
larger
14
Q
What limits kcat/Km?
A
time for electron rearrangement, turnover number, and collision
15
Q
What is the number of kcat/Km that is considered catalytic perfection?
A
10e8 - 10e9 1/(M*s)
16
Q
Generally, efficient enzymes have (high/low) Vmax, Km, kcat, kcat/Km?
A
high Vmax, low Km, high kcat, high kcat/Km
17
Q
With a lineweaver-burk plot equation, what is the Vmax equal to?
A
1/y-intercept
18
Q
With a lineweaver-burk plot equation, what is the Km equal to?
A
slope/y-intercept
19
Q
What makes an irreversible inhibitor, irreversible?
A
it covalently modifies the enzyme so that it cannot return to its active form
20
Q
What is an example of an irreversible inhibitor?
A
Serine Protease
21
Q
Kinetics don’t affect which kind of inhibitor?
A
irreversible
22
Q
What are the effects of reversible inhibitors interacting with an enzyme?
A
lower overall reaction rate, reaction kinetics are changed, and the inhibitor can be released from the enzyme
23
Q
What kind of inhibitor am I describing: the inhibitor competes with the substrate for the active site
A
competitive inhibitor
24
Q
Which inhibitor is considered mutually exclusive?
A
competitive
25
For competitive inhibition, what occurs if [s] is much greater than [I]?
no inhibition is observed
26
What values do competitive inhibitors affect?
Km, not Vmax
(increase in Km)
27
What kind of inhibitor am I describing: inhibitor binds at a site other than the active site and changes the conformation of the enzyme
mixed inhibitor
28
What values do mixed inhibitors affect?
Vmax (decreases) and Km (increase or rarely decrease)
29
What kind of inhibitor is a noncompetitive inhibitor?
mixed
30
What values do noncompetitive inhibitors affect?
Vmax (decreases), no change in Km
31
What kind of inhibitor affects only the catalytic activity and not substrate binding?
Uncompetitive inhibitor
32
What values do uncompetitive inhibitors affect?
Km (decreases) and Vmax (decreases)
33
What kind of inhibitor is Tamiflu?
competitive inhibitor
34
What NSAID is irreversible inhibition of both COX-1 and COX-2?
Aspirin
35
What NSAID is reversible inhibition of both COX-1 and COX-2?
ibuprofen
36
What NSAID is selective inhibition of just COX-2?
Vioxx and Celebrex
37
What is the term for the sequential reaction where the order of the substrate matters?
Ordered
38
What is the term for the sequential reaction where it doesn't matter which substrate goes first/the order doesn't matter?
Random
39
If you have more than one substrate, is there one Km, or does each substrate have its own Km?
Each substrate has a distinctive Km
40
Does allosteric regulation inhibit or enhance enzyme activity?
It does both! Depends if it's a positive or negative effector
41
What is the allosteric effect?
binding of an effector to one subunit affects the active sites of all subunits
42
What is the negative effector of PFK?
PEP: almost a final product of of the pathway that PFK is regulating
43
What is the positive effector of PFK?
ADP
44
Why is ADP the positive effector of PFK?
High concentration of ADP would indicate a need for ATP, which is the product of glycolysis
45
What form are the majority of natural carbohydrates in?
D form
46
What are the left and right symbols for D-Glucose?
RLRR
47
What are the left and right symbols for D-Galactose?
RLLR
48
Pyran is a ___ - membered ring
6
49
Furan is a _____ - membered ring
5
50
Is Beta together or opposite?
together
51
is Alpha together or opposite?
opposite
52
Anomeric carbon forms a covalent bond with an alcohol - what is this called?
glycosidic bond
53
What is a reducing sugar?
sugars with anomeric carbons that have not formed glycosides
54
What is polymerized by glycosidic bonds?
carbohydrate monomers
55
Sucrose make up:
alpha-glucose + beta-fructose
56
Maltose make up:
alpha-glucose + beta-glucose
57
Lactose make up:
beta-galactose + beta-glucose
58
Isomaltose make up:
alpha-glucose + alpha-glucose
59
Cellobiose make up:
beta-glucose + beta-glucose
60
Which polysaccharide has a linear make up?
cellulose
61
Which polysaccharide has a branched make up?
starch
62
Which polysaccharide has a highly branched make up?
glycogen
63
What cleaves glycogen?
glycogen phosphorylase / glycogen debranching enzyme
64
What is a glycoprotein?
protein that has some type of carbohydrate attached to it
65
What kind of carbohydrate is attached to a glycoprotein?
oligosaccharide
66
At what amino acids are the oligosaccharides attached to the glycoprotein?
Asn (N-glycosidic), Ser (O-glycosidic), or Thr (O-glycosidic)
67
What is the purpose of the oligosaccharide added to the glycoprotein
helps stabilize the protein and the helps the organism recognize its own protein vs. foreign proteins
68
Which fatty acids have double bonds?
unsaturated
69
Which fatty acids don't have any double bonds?
saturated
70
What is the saturated 18 C fatty acid
stearic acid CH3(CH2)16COOH
71
What is the monounsaturated 18 C fatty acid
oleic acid CH3(CH2)7CH=CH(CH2)7COOH
72
What is the polyunsaturated 18 C fatty acid with two double bonds?
linoleic acid CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH
73
What is the polyunsaturated 18C fatty acid with three double bonds?
linolenic acid CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH
74
What is the common name for 18:1n9, trans?
Elaidic Acid
75
What causes trans unstaturation?
hydrogenation
76
What makes omega 6 and omega 3 fatty acids "essential"
our body needs them, but cannot make them so we must take them from food
77
What is the 12 C saturated fatty acid called?
Lauric Acid
78
What is the 14 C saturated fatty acid called?
Myristic Acid
79
What is the 16 C saturated fatty acid called?
Palmitic Acid
80
What is a triacylglycerol?
3 fatty acids on a glycerol backbone
81
The more double bonds, the ________ the melting point
lower
82
The longer the acyl chain, the ________ the melting point
higher
83
What are the 4 kinds of membrane bilayers?
glycerophospholipids, sphingomyelins, cholesterol, and isoprenoids
84
What is the make up of a glycerophospholipid?
glycerol-3-phosphate + 2 fatty acids
85
What is a sphingosine?
18 carbon amino alcohol
86
What is the make up of a ceramide?
sphingosine + N-acyl fatty acid
87
What is the make up of a sphingomyelin?
ceramide + phosphoryl head group
88
What is the make up of a cerebroside?
ceramide + single sugar head group
89
What is the make up of a ganglioside?
ceramide + oligosaccharides (including sialic acid)
90
What is Tamiflu an analog of?
Sialic acid
91
What is sterol's make up?
3 cyclohexanes and 1 cyclopentane
92
Which vitamins are isoprenoids?
A, D, and K
93
Vitamins A, D, and K are _______ because of their isoprenoid nature
fat soluble
94
What is the outer leaflet of the membrane composed of?
sphingolipids and phosphatidyl choline
95
What is the inner leaflet of the membrane composed of?
phosphatidyl serine
96
How are the inner and outer leaflets of the membrane's distinct compositions maintained?
it is thermodynamically unfavorable to flip flop
97
What enzyme allows the outer and inner leaflets to flip flop?
flippases (or translocases)
98
What is another term for the flip flop of inner and outer leaflets?
transverse diffusion
99
What is the more common type of switching in the membrane?
lateral diffusion
100
What kind of diffusion is the reason the membrane is so flexible?
Lateral Diffusion
101
Membranes are _________ (structure - wise)
dynamic and fluid
102
What is the main source of energy in the body?
oxidation of carbons in carbohydrates
103
All reactions in vivo occur with a net ________ in free energy
decrease
104
Are metabolic pathways reversible?
No, it is thermodynamically unfavorable to do so
105
What is the first step of every metabolic pathway called and what is unique about it?
First committed step, Delta G of this step must be negative
106
What is the catabolic pathway of glycolysis?
gluconeogensis
107
What are used as energy currency in the cell?
reduced cofactors
108
Reduced cofactors are produced as a result of what?
catabolic activities
109
Where do glycosidic bonds have to take place?
at anomeric carbons
110
What kind of bonds are very unstable/high energy and are therefore favorable to break?
phosphoanhydride
111
What are the results of the breaking of phosphoanhydride bonds?
more resonance stabilization, more solvation in water, and less ionic repulsion
112
Hydrolysis of _________ bonds also releases a large amount of free energy and is therefore a favorable reaction.
thioester
113
What is the oxidized form of NAD?
NAD+
114
What is the reduced form of NAD?
NADH
115
What is the oxidized form of FAD?
FAD
116
What is the reduced form of FAD?
FADH2
117
What is the oxidized form of Q?
Q
118
What is the reduced form of Q?
QH2
119
Which reduced cofactor accepts hydrogen as an element?
FAD and Q
120
Which reduced cofactor accepts Hydride ion?
NAD
121
What coenzyme can carry electrons in the membrane?
coenzyme Q
122
What is the tendency of a substrate to accept electrons/to become reduced?
reduction potential
123
These are the major functions of which organelle: citric acid cycle, electron transport and oxidative phosphorylation, fatty acid oxidation, and amino acid breakdown
mitochondrion
124
These are the major functions of which organelle: glycolysis, pentose phosphate pathway, fatty acid biosynthesis, and many reactions of gluconeogenesis
cytosol
125
These are the major functions of which organelle: DNA replication and transcription, RNA processing
nucleus
