250-259 Flashcards
(86 cards)
1
Q
Covalent bonds:
A
Covalent bonds: Strong molecular interactions mediated by shared electrons.
2
Q
Noncovalent bonds:
A
Noncovalent bonds: Weak, reversible molecular interactions
3
Q
Van der Waals bonds:
A
Van der Waals bonds: A nonspecific attraction (occurs when any two
atoms are 3–4 Å apart).
4
Q
water
A
Polar.
■ Triangular.
■ Highly cohesive.
■ Excellent solvent for polar molecules.
■ Weakens ionic and H-bonds.
5
Q
Catalyzes the reaction between CO2 and H2O.
■ Extremely fast enzyme.
A
Carbonic Anhydrase
6
Q
Located largely in erythrocytes and kidneys.
■ A metalloenzyme: contains zinc.
A
Carbonic Anhydrase
7
Q
The total energy of a closed system is conserved.
A
First law of thermodynamic
8
Q
The entropy of a closed system always increases.
A
■ Second law of thermodynamics
9
Q
Direct calorimetry:
A
Direct measurement of the amount of heat produced
in a given system.
10
Q
Indirect calorimetry:
A
Measurement of the amount of heat produced in
terms of inhaled O2 and exhaled CO2.
11
Q
Highly specific catalysts for biochemical reactions.
■ Classified according to their mechanism of action.
A
enzymes
12
Q
https://drive.google.com/open?id=0B8uJUY-tie8GbzB2bGljMl93NHc
A
https://drive.google.com/open?id=0B8uJUY-tie8GR1ZtdkU4VU50aVk
13
Q
Composed of proteins combined with nonprotein structures (either
organic or inorganic) that aid in their function
A
Metallic Coenzymes
14
Q
Coenzymes
■ Cofactors
■ Prosthetic groups
A
metallic coenzymes
15
Q
Coenzyme:
A
Nonprotein portion of an enzyme.
16
Q
Apoenzyme:
A
Protein portion of an enzyme. Catalytically inactive by itself.
17
Q
Haloenzyme: ■
A
Complete, catalytically active enzyme.\
= Apoenzyme + Coenzyme
18
Q
Isozymes:
A
Enzymes with subtle molecular differences that catalyze the
same reaction.
19
Q
Oxidoreductases:
■
A
Catalyze redox reactions.
20
Q
Transferases:
A
Catalyze the transfer of functional groups.
21
Q
Hydrolases: ■
A
Catalyze bond cleavage by hydrolysis.
22
Q
Isomerases:
A
Catalyze a change in molecular structure.
23
Q
Lyases:
A
Catalyze bond cleavage by elimination.
■
24
Q
Ligases:
A
Catalyze the union of two molecules.
25
Substrate-binding induces a conformational change in an enzyme.
■ The energy produced by these changes enables the reactions to progress
induced fit model
26
Increasing substrate concentration ---- reaction rate only until the
------ ------ sites are saturated.
Increasing substrate concentration increases reaction rate only until the
enzyme-binding sites are saturated.
27
Maximum reaction velocity (Vmax) is achieved when any further ----
in substrate concentration ------ increase reaction rate.
## Footnote
Maximum reaction velocity (Vmax) is achieved when any further increase
in substrate concentration does not increase reaction rate.
28
The Michaelis constant (Km) is the substrate concentration when the initial
reaction velocity (vi) is ----- of the maximum reaction velocity (Vmax).
## Footnote
The Michaelis constant (Km) is the substrate concentration when the initial
reaction velocity (vi) is half of the maximum reaction velocity (Vmax).
29
ΔG = ΔGP− ΔGS
Determines reaction direction.
■ If ΔGS \> ΔGP, then ΔG will be negative and the reaction will proceed
spontaneously toward equilibrium.
30
Equilibrium is attained when ΔG = ----
Equilibrium is attained when ΔG = 0.
31
vi =
Vmax · [S]
Km + [S]
https://drive.google.com/open?id=0B8uJUY-tie8GU3FWZ1l6T3JJa3M
32
Reactions are based on their ΔG (see Table 5–2).■
Exergonic
■ Endergonic
33
A: Any reaction with enzyme present.
■ B: Equilibrium ----- of the reaction.
■ Enzymes have--- ---- on reaction equilibrium
A: Any reaction with enzyme present.
■ B: Equilibrium constant of the reaction.
■ Enzymes have no effect on reaction equilibrium
34
https://drive.google.com/open?id=0B8uJUY-tie8GOUVDUUlxSV9lSjA
35
rxn rate
Determined by the activation energy.
■ Attaining activation energy requires an increase in reactant kinetic energy.
36
Kinetic energy is largely influenced by ----- and substrate ------
■ Enzymes ---- the activation energy of a reaction, ------ the rate
Kinetic energy is largely influenced by temperature and substrate concentration.
■ Enzymes lower the activation energy of a reaction, accelerating the rate
37
Negative
Released
G
nrg flow
= exergonic
38
Positive
Required
G
nrg flow
=endergonic
39
https://drive.google.com/open?id=0B8uJUY-tie8GZ1lmejcxcVQxVW8
https://drive.google.com/open?id=0B8uJUY-tie8GUVJHdHNPTDhjUGc
40
Inhibitor and substrate compete for the same binding site.
■ Inhibition can be reversed with increased substrate concentration.
comp. inh.
41
No effect on Vmax.
■ Km is increased
comp. inh
42
comp inh
https://www.google.com/search?rlz=1C5CHFA\_enUS763US763&biw=1379&bih=749&tbm=isch&sa=1&q=competitive+inhibition+graph&oq=competitive+inhibition+graph&gs\_l=psy-ab.3..0l2j0i5i30k1l2.9067.10098.0.10219.6.6.0.0.0.0.172.643.0j5.5.0....0...1.1.64.psy-ab..1.5.641....0.sdGbc8vRG\_4#imgrc=uKXNNJ82kEt77M:
43
non comp inh
https://www.google.com/search?rlz=1C5CHFA\_enUS763US763&biw=1379&bih=749&tbm=isch&sa=1&q=non+competitive+inhibition+graph&oq=non+competitive+inhibition+graph&gs\_l=psy-ab.3..0.69599.70182.0.70391.4.4.0.0.0.0.124.456.0j4.4.0....0...1.1.64.psy-ab..0.4.454...0i13k1j0i7i30k1j0i8i7i30k1j0i13i5i30k1j0i5i30k1.0.vyq3HplZf8s#imgrc=ji\_YDOEADuS4xM:
44
Inhibitor and substrate bind simultaneously.
■ The two binding sites do not overlap.
non comp inh
45
Inhibition cannot be reversed with increased substrate concentration.
■ Vmax is decreased
non comp inh
46
No effect on K
non comp inh.
47
non comp injh
Inhibitor binds only after the substrate is bound first.
■ The two binding sites do not overlap
48
Vmax is decreased.
■ Km is decreased
non comp inh
49
Inhibitor ------- alters the molecular structure of an enzyme, prohibiting
its continued activity.
Inhibitor irreversibly alters the molecular structure of an enzyme, prohibiting
its continued activity.
50
cov modification
Reversible or irreversible enzymatic
modification alters enzyme conformation,
thus affecting its activity
51
cov modification
Phosphorylation (kinases)
■ Dephosphorylation (phosphatases)
■ Methylation (methyltransferases
52
Allosteric enzyme:
Allosteric enzyme: A regulatory enzyme that has both an active site (for the
substrate) and an allosteric site (for the effector).
53
If the effector is present, it binds to the ---- -----causing a conformational
change to the ---- site, which then changes (increases or decreases)
the enzymatic activity
## Footnote
If the effector is present, it binds to the allosteric site causing a conformational
change to the active site, which then changes (increases or decreases)
the enzymatic activity
54
If no effector is present, the enzyme can still act on substrate -----y (via
the active site) to produce product.
## Footnote
If no effector is present, the enzyme can still act on substrate normally (via
the active site) to produce product.
55
A form of feedback regulation in which an enzyme of a ---- ----
is controlled by the end product of that same pathway. (See Figure 5–7.)
■
A form of feedback regulation in which an enzyme of a metabolic pathway
## Footnote
is controlled by the end product of that same pathway. (See Figure 5–7.)
■
56
Often catalyzes a committed step early in a metabolic pathway.
■ Simple Michaelis–Menten kinetics are not followed.
allosteric rxn
57
Proenzyme (zymogen):
Proenzyme (zymogen): Catalytically inactive enzyme precursor.
58
Proteases cleave the protein fragment (propeptide) of the zymogen, -----
the enzyme
Proteases cleave the protein fragment (propeptide) of the zymogen, activating
the enzyme
59
Trypsinogen 2 Trypsin
Enteropeptidase
60
Fibrinogen 2 Fibrin
Thrombin
61
The most fundamental carbohydrate; required for carbohydrate metabolism,
storage, and cellular structure.
glucose
62
If carbohydrates are not absorbed by dietary intake, they are generally converted
to glucose in the liver.
glucose
63
Monosaccharides:
The simplest carbohydrates.
64
Number of carbon atoms:
Trioses, tetroses, pentoses, hexoses, heptoses
65
Functional group:
Aldoses (aldehyde) or ketoses (ketone)
66
6–2).
■ Reducing sugars: Contain ----- groups that are oxidized to
-----. For example: glucose, fructose, galactose, maltose,
lactose.
6–2).
■ Reducing sugars: Contain aldehyde groups that are oxidized to
carboxylic acids. For example: glucose, fructose, galactose, maltose,
lactose.
67
D-form:
■
Hydroxyl group on right. Most common form.
68
L-form:
Hydroxyl group on left.
69
Disaccharides:
Glycosidic condensation of two monosaccharides
70
Maltose →
glucose + glucose; via maltase
71
Sucrose →
glucose + fructose; via sucrase
72
Lactose →
glucose + galactose; via lactase.
73
Oligosaccharides:
Glycosidic condensation of 2–10 monosaccharides
74
■ Polysaccharides:
■ Polysaccharides: Glycosidic condensation of \>10 monosaccharides.
75
polysach
Mostly used as storage molecules or cellular structural components.
■ Can be linear or branched
76
https://drive.google.com/open?id=0B8uJUY-tie8GOUNvV0RIU3ZuMVU
https://drive.google.com/open?id=0B8uJUY-tie8GVXQ4cHprT0dzbzQ
77
A homopolymer of glucose l
STARCH
inked by a–1, 4 glycosidic bonds.
78
STARCH
The major glucose storage molecule in plants.
79
Contains unbranched helical amylose (15–20%) and branched (a–1, 6)
amylopectin (80–85%).
STARCh
80
Amylases:
The key enzymes in starch catabolism
81
Dextrins:
D-glucose polymer intermediates in starch hydrolysis. “Limit
dextrins” are the fragments that remain following hydrolysis
82
https://drive.google.com/open?id=0B8uJUY-tie8GWVZRS0VOUmQwQ2c
https://drive.google.com/open?id=0B8uJUY-tie8GQnlFMVBBVGZ6bFE
83
glycogen
A homopolymer of glucose linked by a-1, 4 glycosidic bonds.
■ The major glucose storage molecule in animals
84
glycogen
■ Contains numerous branch points via a-1, 6 glycosidic linkages.
85
https://drive.google.com/open?id=0B8uJUY-tie8GZmRzNm9xSlZTaHM
https://drive.google.com/open?id=0B8uJUY-tie8GY1VNMG5aWXJjd1k
86
