ENZYME Flashcards
(109 cards)
1
Q
Proteins that act as catalysts for cell
reactions
A
Enzyme
2
Q
Speed up reactions without being
consumed
A
Enzyme
3
Q
Each enzyme is specific to a
A
single reaction
4
Q
Most are globular proteins; some are RNA
A
Enzyme
5
Q
Enzymes are mostly —– proteins
A
globular proteins
6
Q
they are Sensitive to pH, heat, and denaturation
A
Enzyme
7
Q
enzymes are Sensitive to — —- and —–
A
pH, heat, and denaturation
8
Q
Activity is regulated by substances in cells
A
Enzyme
9
Q
Used in bread rising and alcohol
fermentation
A
Enzyme
10
Q
contain only protein
A
Simple enzymes
11
Q
have a protein + a nonprotein part
A
Conjugated enzymes
12
Q
protein part; cofactor = nonprotein part
A
Apoenzyme
13
Q
apoenzyme + cofactor (active form)
A
Holoenzyme
14
Q
can be metal ions or coenzymes
A
Cofactors
15
Q
are organic, often from B vitamins
A
Coenzymes
16
Q
may be permanently or temporarily bound
A
Cofactors
17
Q
enzymes are used nin
A
bread rising and alcohol fermentation
18
Q
are named based on their function (reaction catalyzed and substrate identity), not structure.
A
Enzymes
19
Q
3 Key Points in Enzyme Naming
A
Suffix -ase:
Type of Reaction:
Substrate Identity:
20
Q
Identifies a substance as an enzyme.
A
Suffix -ase:
21
Q
often indicates the type of reaction.
A
prefix
22
Q
Catalyzes oxidation reactions.
A
Oxidase:
23
Q
Catalyzes hydrolysis reactions.
A
Hydrolase:
24
Q
Enzyme names may also include the
A
substrate
25
Oxidizes glucose.
Glucose oxidase:
26
Converts pyruvate.
Pyruvate carboxylase:
27
Dehydrogenates succinate.
Succinate dehydrogenase:
28
Hydrolyze urea
Urease
29
Hydrolyze lactose
Lactase
30
are grouped into six major classes based on the reactions they
catalyze.
Enzymes
31
Enzymes are grouped into six major classes based on the reactions they catalyze.
1.Oxidoreductases
2.Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases
32
Catalyze oxidation-reduction reactions.
Oxidoreductases
33
Require a coenzyme that is oxidized or reduced.
Oxidoreductases
34
(removes hydrogen atoms)
Lactate dehydrogenase
35
Catalyze the transfer of a functional group between molecules.
Transferases
36
2 subtypes of Transferases
Transaminases:
Kinases:
37
Transfer amino groups.
Transaminases:
38
Transfer phosphate groups (ATP → ADP).
Kinases:
39
Catalyze hydrolysis reactions (addition of water to break bonds).
Hydrolases
40
Central to digestion.
Hydrolases
41
Break glycosidic bonds.
Carbohydrases:
42
Break peptide bonds.
Proteases:
43
Break ester bonds.
Lipases:
44
Catalyze the addition or removal of a group to/from a double bond.
Lyases
45
Removes water components from a bond.
Dehydratase:
46
Adds water components to a bond.
Hydratase:
47
Catalyze isomerization reactions (rearrange atoms within a
molecule).
Isomerases
48
Only one reactant and one product.
Isomerases
49
Catalyze the bonding of two molecules, using ATP for energy.
Ligases
50
is required because these reactions are energetically unfavorable.
ATP
51
4 Models of Enzyme Action
Enzyme Active Site:
Enzyme-Substrate Complex:
Lock-and-Key Model:
Induced-Fit Model:
52
Small portion of enzyme involved in catalysis.
Enzyme Active Site:
53
Three-dimensional structure formed by protein folding.
Enzyme Active Site:
54
A "crevice-like" location in the enzyme.
Enzyme Active Site:
55
Substrate binds to enzyme
’
s active site.
Enzyme-Substrate Complex:
56
Substrate binds to
enzyme's active site.
57
binds to enzyme’s active site.
Substrate
58
Alternative pathway with lower activation energy.
Enzyme-Substrate Complex:
59
Forms intermediate complex for faster product formation.
Enzyme-Substrate Complex:
60
Enzyme active site has fixed shape.
Lock-and-Key Model:
61
Substrates with complementary shape fit perfectly.
Lock-and-Key Model:
62
Like a key fitting into a lock.
Lock-and-Key Model:
63
Enzyme active site changes shape slightly.
Induced-Fit Model:
64
Flexibility allows the enzyme to adjust.
Induced-Fit Model:
65
allows the enzyme to adjust.
Flexibility
66
Explains enzyme specificity with flexibility.
Induced-Fit Model:
67
Key Interactions of enzymes
Electrostatic
hydrogen bonds and hydrophobic interactions.
Metal ions or cofactors assist binding.
68
Enzyme specificity =
selectivity for substrates.
69
Determined by shape of active site.
Enzyme Specificity
70
Ensures correct reaction with correct substrate.
Enzyme Specificity
71
Helps regulate metabolic pathways efficiently.
Enzyme Specificity
72
4 Types of Specificity:
1.Absolute Specificity
2.Group Specificity
3.Linkage Specificity
4.Stereochemical Specificity
73
One enzyme, one substrate, one reaction.
Absolute Specificity
74
Catalase → breaks only H2O2.
Absolute Specificity
75
Acts on molecules with certain groups.
Group Specificity
76
Carboxypeptidase → cleaves peptide ends.
Group Specificity
77
Recognizes specific bonds, not whole structure.
Linkage Specificity
78
Phosphatases → hydrolyze ester bonds.
Linkage Specificity
79
Distinguishes between isomers (e.g., L vs D).
Stereochemical Specificity
80
4 Factors that Affect Enzyme
1. Temperature
2. pH
3. Substrate Concentration
4. Enzyme Concentration
81
is a measure of the rate at which an
enzyme converts substrate to products in a
biochemical reaction.
Enzyme activity
82
Increased temp =
faster enzyme-substrate
collisions
83
Too high temp =
denaturation, loss of activity
84
Optimum temp for humans:
37°C
85
Fever above ------ may be fatal
40°C
86
kill bacteria by enzyme denaturation
Autoclaves
87
Enzymes lose shape →
inactive at high heat
88
Graph shows peak at optimum temperature
Temperature
89
Enzymes work in narrow
pH range
90
Optimum pH =
maximum enzyme activity
91
Pepsin (stomach) → active at pH
pH 2.0
92
Trypsin (intestine) → active at pH
pH 8.0
93
it affects R-group charges
pH changes
94
occurs if pH shifts too far
Denaturation
95
preserves pickled foods
(inhibits microbes)
Acidic pH
96
More substrate =
faster reactions (to a
point)
97
More substrate = faster reactions (to a
point)
Substrate Concentration
98
Activity levels off → saturation point
reached
99
Activity levels off → saturation point
reached
Substrate Concentration
100
All active sites occupied =
max rate
101
must wait for enzyme turnover
Substrate
102
Turnover number: substrate converted
per
minute
103
High substrate won’t increase rate after
saturation
104
More enzyme =
more reactions (if
substrate present)
105
Rate increases with enzyme concentration
Enzyme Concentration
106
cells use few
molecules
Enzymes reused
107
Efficient for saving energy and resources
Enzyme Concentration
108
High enzyme + high substrate =
fastest rate
109
More enzyme → more
active sites available
