Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochemistry I > Exam 2 > Flashcards

Exam 2 Flashcards

(69 cards)

Start Studying
1
Q

Many diseases are caused by an excess of _____ or deficiency of a ______

A

product, substrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Active site

A

region where catalysis occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Substrate

A

Reactant of the enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Product

A

Molecules produced as the result of a reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Enzymes work best in what conditions

A

temps below 100 C and a neutral pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How much faster is a catalyzed reaction than an uncatalyzed one

A

10^6-10^14 times faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why are side products rare in enzyme reactions

A

because enzymes are usually highly specific in terms of reaction selectivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are enzymes regulated (3 ways)

A
  1. covalent modification
  2. levels of enzyme synthesized
  3. allosteric regulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Oxidoreductases

A

used in redox reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Transferases

A

used when functional groups are being transferred

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Hydrolases

A

water cleaving bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Lyases

A

forms a double bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Isomerases

A

intermolecular rearrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Ligases

A

creating a bond with ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do enzymes work

A

by lowering the energy of activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Rate enhancement

A

e^(ΔΔG‡/RT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When ΔG‡ is larger, the reaction is

A

slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

At 298K, decreasing ΔG‡ by 5.7 kJ/mol, the speed of reaction increases

A

10 fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Catalytical enzyme mechanisms (5 types)

A
  1. acid-base
  2. covalent
  3. metal ion
  4. proximity and orientation effects
  5. preferential binding of the transition state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Example of acid-base catalysis

A

RNAase A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Covalent catalysis

A

transient formation of an enzyme-substrate covalent bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Covalent catalysis usually involves a reaction between ______ on the catalyst and the _____ group on the substrate

A

nucleophilic, electrophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 4 amino acids that are typically used as substrates in covalent catalysis

A

ser, cys, his, lys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Metal ion participation in metal ion catalysis (3)

A
  1. binding to substrates to orient them properly
  2. Mediating redox reactions
  3. Electrostatic stabilization and shielding negative charges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What metal ion catalyzes carbonic anhydrase formation
zinc
26
What is the purpose of metal ion catalysis
to create a stronger nucleophile
27
Net reaction of glycolysis
- 1 molecule of glucose consumed -2 molecules of ADP are converted to ATP -2 molecules of NAD+ are reduced to NADH
28
Step 1 glycolysis
Hexokinase Requires Mg2+ Generates G6P
29
G6P activates _____ and then _____
glucose, traps it in the cell
30
Step 3 glycolysis
Phosphofructokinase (PFK) F6P-> 1,6 FBP
31
Hexokinase is a
transferase
32
Step 3 of glycolysis is
irreversible, critical regulatory point/committed step
33
PFK2 generates _____ which is a regulator for ______ and _____
2,6 FBP, gluconeogenesis, glycolysis
34
Irreversible steps of glycolysis
1, 3, 10
35
What steps in glycolysis use ATP
1 and 3
36
Step 4 of glycolysis
Aldolase 1,6 FBP -> 2 triose compounds operates via aldol cleavage
37
Step 6 of glycolysis
GAPDH NAD+ reduced to NADH GAP -> 1,3-BPG
38
Step 6 of glycolysis is the only ________ step
oxidation
39
Step 7 glycolysis
Phosphoglycerate kinase (PGK) 1,3-BPG + ADP -> 3-PG + ATP
40
Steps 7 and 10 of glycolysis are examples of
substrate level phosphorylation
41
Step 10 of glycolysis
Pyruvate Kinase Phosphoenol pyruvate (PEP)-> pyruvate
42
Catalytic triad
ASP - HIS- SER
43
High energy phosphates (4)
- acetyl phosphate -1,3-BPG -Phosphocreatine -Phosphoarginine
44
Low energy phosphates (2)
- alpha-D-glucose-6-phosphate - 1-glycerol-3-phosphate
45
Preferential binding of the transition state
this is the concept that the enzyme will bind tighter to the transition state so the complex is forced to complete the original reaction instead of reacting with a different compound
46
_____ bonds link the anomeric carbon to other compounds
Glycosidic
47
Why can humans not digest cellulose
We cannot digest the 1,4-beta linkages found in cellulose
48
True/False: A low Kcat/Km ratio is favorable because it indicates a higher enzyme efficiency
False. A high Kcat/Km ratio indicates a higher enzyme efficiency
49
____ Kcat is favorable, ______ Km is favorable
high, low
50
Competitive inhibitors bind to
enzyme only
51
Competitive inhibition increases _____ and does not affect ____
Km, Vmax
52
Catalytic mechanism by serine proteases
1. preferential binding of transition state 2. Covalent catalysis (Ser195 binds substrate) 3. Proximity/orientation effects (Ser195 positioned for nucleophilic attack) 4. Acid/base catalysis (His57 acts as both an acid and a base, Asp102 acts somewhat as a base)
53
Summary of lysozyme mechanism
1. Binds hexasaccharide unit, distorts D residue 2. Glu35 transfers proton to O1 bridging D and E rings 3. Asp52 nucleophilically attacks C1 of D ring to form glycosyl-enzyme intermediate 4. Water replaces E ring product in active site and Glu35 hydrolyzes covalent bond
54
Km=[S] when
V0=1/2Vmax
55
Enzymes with small Km achieve maximal efficiency at ____ substrate concentrations
low
56
Trypsin specificity pocket
Deep. Trypsin binds lysine and arginine
57
Chymotrypsin specificity pocket
binds aromatic compounds. specificity pocket is large
58
Elastase specificity pocket
Small uncharged residues
59
What is alpha in liveweaver-burke plots
a factor by which substrate concentration must be increased in order to overcome the effects of the inhibitor
60
Uncompetitive inhibitors bind
ES
61
T/F: Uncompetitive inhibition cannot be overcome by addition of S
true
62
Uncompetitive inhibition _____ Vmax and Km
decreases
63
Lines on uncompetitive lineweaver-burke are
parallel
64
Noncompetitive inhibitors bind
E and ES
65
Pure noncompetitive inhibition
Vmax decreases Km stays the same
66
Mixed noncompetitive
If K1 is larger -> inhibitor favors binding enzyme, mimics competitive inhibition If K1' is larger -> inhibitor favors binding ES which mimics uncompetitive inhibition Lines on Linewever-burke do not intersect on an axis Vmax decreases
67
Inactivation of serine proteases
-irreversible -DIPF inactivates -Lovers Vmax but doesn't affect Km
68
Enzymes that catalyze reactions near equlibrium (delta G near 0)
not good sites to control pathway flux rate is almost entirely controlled by substrate/product concentrations
69
Enzymes that catalyze far from equilibrium (delta G<<0)
-act as chokepoints that can be used to control entire pathway

Biochemistry I (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions