biochem1 Flashcards
(140 cards)
1
Q
what’s an oligopeptide?
A
very small chain of amino acids
2
Q
what’s a polypeptide?
A
longer chain of amino acids
3
Q
what is an essential amino acid?
A
amino acid you cannot synthesize and need to ingest
4
Q
what is a non essential amino acid?
A
amino acid you synthesize and do not need to ingest
5
Q
What does R group help determine?
A
chemistry such as:
1) if substrate will bind to active site; protein will fold; mechanisms in enzyme pocket.
6
Q
1) 5HTT is a monoamine transport protein responsible for the reuptake of serotonin from synapses in the central nervous system. 5HTT also has a high affinity for which amino acid?
Serotonin
A) Arg B) Trp C) Val D) Glu
Solution: The stem states that 5HTT transports serotonin. It is logical to assume that it will also transport, and therefore have high affinity for, something very similar to serotonin in structure and polarity. Answer B, tryptophan, is certainly a possibility given that the aromatic portion of serotonin is nearly identical to that of Trp. Answer A, arginine, would not be a good candidate because it has a positively-charged side chain and no aromatic group. Answer C, valine, is a much smaller non-polar amino acid. Answer D also has a negatively charged side chain. This leaves Answer B as the best answer.
A
B
7
Q
What tis the order of deprotonation?
A
1) Alpha- COOH group
2) -R group acidic
3) -R group, His
4) alpha- NH3+ Group
5) -R group Basic
8
Q
what is a zwitterion?
A
dipolar version of an amino acid that has neutral ion
9
Q
Are amino acids weak or strong acids?
A
weak
10
Q
What is the isoelectric point of a neutral? acidic? basic?
A
pI neutral= average of pKa- amine group and pKa- carboxyl group
pI acidic= average of pKa- acidic R group and pKa carboxyl group.
pI basic= average of pKa amine group and pKa basic R group.
11
Q
2) If the pH of a solution is below the pKa of the carboxylic acid of isoleucine, what will be the charge on the majority of isoleucine molecules in that solution?
A) 2+ B) 1+ C) 0 D) 1-
A
Isoleucine has a non-polar aliphatic side chain.
B
12
Q
What reaction is forms peptide bonds? what attacks what?
A
- dehydration synthesis and acyl substitution
- Amine group nitrogen (nucleophile) from the NEW amino acid attacks the carbonyl carbon (electrophile) on the C terminus of the growing peptide chain.
13
Q
Peptides written, read and synthesized in the direction?
A
N terminus –> C terminus
14
Q
What has double character in the amino acid?
A
BOTH the C=O bond and the C-N bond in a peptide bond have DOUBLE BOND character
15
Q
What does double bond character?
A
RIGID peptide bond with limited rotation
16
Q
What happens during protein hydrolysis? where does trypsin and chymotrypsin cleave?
A
Trypsin and chymotrypsin cleaves proteins not the carboxyl side of specific amino acid residues;
- trypsin= arginine, lysine
- chymotrypsin= phenylalanine, tryptophan, tyrosine.
17
Q
What is primary sequence?
A
amino acid sequence
18
Q
what is alpha helix secondary protein?
A
- alpha helix is a polypeptide chain that is rod-shaped and coiled in a spring-like structure, held by intramolecular hydrogen bonds. A helix can be left-handed (beta) or right-handed where the alpha helix is always right-handed.
19
Q
what is beta helix secondary protein?
A
Beta sheets is a pleated conformation of two or more fully extended peptide chains that can be parallel or antiparallel; the hydrogen bonds are flexible but not elastic and are inter-molecular. It is necessary for the carboxyl and amide moieties to line up properly in order for every residues to participate in 2 hydrogen bonds.
20
Q
In a alpa helix, is the R group pointed toward, away, perpendicular or parallel from the alpha helix cylinder? What about in Beta sheet?
A
away in alpha cylinder
parallel in beta sheet.
21
Q
What amino acid is found outside of alpha helices and why?
A
Proline is the first residue at the END of an alpha helix and it cannot be inside the helices a it is non polar hydrophobic and to big –> introduces kinks and turns.
22
Q
what are two examples of secondary structures of amino acids found in body?
A
keratin and fibroin
23
Q
what’s a tertiary structure?
A
Geometric, three-dimensional folding of the alpha helices, beta sheets, and other moieties to form a functional globular or structural protein.
24
Q
What are the six interactions between amino acid that contribute to a 3* protein structure?
A
- Hydrogen bonding – non-covalent bond between either backbone atoms (N-H or C=O) or side chains (amine groups, carboxyl groups, alcohol groups)
- Disulfide bonds – covalent bond between the sulfurs of two cysteine residues
- Hydrophobic/hydrophilic interactions – in soluble proteins, the hydrophobic amino acids will collapse into the protein core. In membrane proteins, the hydrophilic membranes will be either outside the membrane in the cytoplasm or inside the core of the protein, away from the membrane bilayer, with hydrophobic amino acids located within the membrane bilayer.
- Ionic interactions (salt bridges) – charge-charge interactions between a positively charged amino acid and a negatively charged amino acid
- Van der Walls forces – intermolecular forces that repel atoms away from each other (steric hindrance)
- Proline turns – because of proline’s unusual cyclical shape, introducing a proline into an alpha helix or beta
sheet will cause a kink. Proline turns are also found at the end of most strands involves in beta sheets. The sharp turn helps the chain redirect in such a way that the next segment is running antiparallel to the previous segment in the sheet formation.
25
What does L and D- stand for in front of an amino acid? How do you distinguish them?
D – and L- amino acids are mirror images of one another, and they are not identical compounds.
By convention, if the carboxylic acid (-COOH) group in a fisher projection is placed at the top and the –R group is placed at the bottom, then L-amino acids will have the amine group on the left and D- amino acids will have the amine group on the right.
26
what's quaternary structure?
multiple folded proteins into a multisubunit and two beta subunits
27
What's an example of a quaternary structure in the body?
Hemoglobin- two alpha and two beta subunits.
28
What type of binding does hemoglobin undergo? what does it mean?
Positive cooperativity- ligand affinity increases with binding of more subsequent ligand.
29
what is a globule protein?
fully folded protein
30
what is a molten globule protein?
partially folded
31
what is a molten protein?
fully denatured/ unfolded
32
what are examples of amino acids with CHARGED side chains? (acidic, positive, negative)
```
ACIDIC/ NEGATIVE charged:
glutamic acid (Glue, E) and aspartic acid (Asp,D)
```
POSITIVE/BASIC:
lysine (Lys, K), arginine (Arg, R) and histidine (His, H)
33
can amino acids with CHARGEd side chains be found int the interior of a protein?
No unless it is bound to a complimentary molecule/ side chain of opposite charge,w which would cancel out net charge and be in interior of globular protein.
34
What is true of a hydrophobic core?
hydrophobic R groups fold into the interior of a globular protein to escape water. + some smaller polar complimentary molecules to stabilize core.
35
What is true of hydrophilic surface? what proteins are found?
majority of R groups are either polar or charged
36
What are electrostatic interactions? what is the effect on globular protein interaction?
Interactions between charged- R groups, both encourage act of folding itself and stabilize protein and its folded state.
37
What is the effect of Hydrogen bonding on protein folding?
H bond between - R groups also encourages folding and stabilizes folded protein.
38
What are Disulfide bonds? what is the effect on protein interaction?
Two oxidized cysteine residues form a disulfide (R-S-S-R) bond. Strongest type of protein folding interaction.
39
What are salt bridges, when are they formed?
Formed when acidic and basic R groups undergo neutralization reaction resulting in salt. Maintain deoxytaunt form.
40
An alpha helices with proline turn can be considered as ?
disrupting 2* structure or contributing 3* structure.
41
What is solvation layer?
a layer of water that surrounds dissolved protein.
42
Why are hydrophobic proteins found in the interior when in a polar solvent or in water?
Interaction of non polar/ hydrophobic a.a with water or polar solvent requires too much energy and is not favored. Therefore polar amino acids surround the non polar, because that interaction of polar a.a and solvent (water or polar) is much me favored as it requires less enthalpy/ energy and leads to an increase in entropy.
--> MAJOR CONTRIBUTION TO OVERALL CONFORMATIONAL STABILITY OF FOLDED PROTEIN
43
What are the 4 protein denaturing agents?
1) acid
2) heat
3) urea
4) mercaptoethanol
44
Is it possible to get a denatured protein to re-fold? How
Most likely not.
Only possible the proteins as slowly denatured with detergent and Disulfide bond aren't broken- it can reform secondary structure.
45
What is Electorphoresis?
separating protein based on fixe. the smallest protein will go the furthest.
46
Which amino acid will go further (furthest toward positive charge) on electrophoresis gel; Phenylalanine or glycine?
glycine- smallest amino acid
47
what is isoelectric focusing? How does it work?
Separating proteins based on pI.
A protein in a region of the gel with a pH lower than its isoelectric point will be positively charged (because it will be fully protonated) and so will move toward the negative cathode. A protein in a region with a pH higher than its isoelectric point will be negatively charged (because it will be fully unprotonated) and so will move toward the positive anode. As the protein moves through increasing pH in the gel, the protein’s charge will decrease until it reaches the pH of its pI, at which point it will become neutral.
48
In Isoelectric focusing with pH gradient which amino acid will go to the positive and which amino acid will go to negative side;
serine; histidine; aspartic acid; leucine; cysteine
serine pI acidic= (9+2)/2= 5.5
3.5 --> toward positive side of gradient
histidine pIbasic= (9+6.04)/2= 7.5
1.5--> toward middle of gradient
Asp pIacidic= (3.71+1.95)/2= 2.83
--> toward positive side of gradient
leucine pI= (9.58+2.32)/2= 5.95 --> toward middle of gradient sie
cysteine pI= (10.28+8.14)= 9.21
toward negative side of gradient
49
What are four types of non enzymatic proteins? give examples for each
Binding proteins= hemoglobin, calmudolin, histones, TF, troponin, tropomyosin,
Immune system =ntibodies and antigens
Structural proteins= actin, tubular, keratin
motor proteins= dyneins and kynesins (+)
50
What is the difference between
Both catalysts and enzymes increase the rate of a reaction by lowering the activation energy. Enzymes, however, are organic molecules, while catalysts can be inorganic molecules (like metal ions).
51
How do enzymes affect a) reaction rate? b)energy of activation c) equilibrium d) Keq e) yield f) percent yield?
a) increase reaction rate
b) lower activation energy
c) DO NOT affect equilibrium
d) DO NOT affect Keq
e) DO NOT affect yield
f) DO NOT affect percent yield.
52
How do each affect reaction rate:
a) pH
b) temp
c) substrate concentration
d) enzyme concentration
a) enzymes work best at optimal pH and change in pH leads to decrease in reaction rate.
b) optimal temperature. too low temps = decreased reaction rate, too high= denature enzyme and low reaction rate. mild temperature increase can increase reaction rate.
c) At low substrate concentrations, the reaction rate will increase rapidly until reach saturation- decrease/ and stabilize.
d) similar saturation curve than for substrate- if concentration is low, adding enzymes will increase reaction rate but it too much enzyme it will decrease and stabilize.
53
What are the different enzyme reaction type? what's the mnemonic?
OverTheHILL
Oxidoreductases= REDOX
Transferases= Transfer functional group
Hydrolases= Hydrolysis
Isomerases= rearrangements
Lyases - cleavage / synthesis
Ligases= addition or synthesis of LARGE molecules, usually ATP dependent.
54
Two theories of enzyme specificity are: and & . Which of these two theories has been largely dismissed by scientists? Why has it been dismissed?
induced fit and lock and key.
Lock and key has been dismissed because it owed mean a rigid inflexible active site.
55
What's a cofactor?
A general term for any species required by an enzyme to function; coenzymes and
prosthetic groups are both examples of cofactors.
56
what's a coenzyme?
Non-protein species NOT permanently attached to the enzyme but required by the enzyme to function.
57
what's a prosthetic group?
Non-protein species that ARE permanently attached to the enzyme and are required by the enzyme to function.
58
what is a common coenzyme in the body?
NAD
59
what is a simple protein?
Protein that contains only amino acids and no non-protein cofactors or
prosthetic groups. If it is a simple protein that is an enzyme, it is called an apoenzyme.
60
what is a conjugated protein?
Protein that is associated with its cofactors, either covalently or via intermolecular attractions. Hemoglobin is a conjugated protein because it contains the non- protein heme group. If it is a conjugated protein that is an enzyme, together with its cofactors it is called a holoenzyme.
61
what are fat soluble vitamins?
A,D,E,K
62
what are water soluble vitamins?
all vitamins the are not A ,D, E ,K
63
What is the difference between vitamins and minerals?
Vitamins are relatively small, organic molecules that are essential nutrients required in small amounts for proper metabolism.
Minerals inorganic elements or compounds necessary for bone formation (calcium and phosphate), ion gradients (sodium and potassium), oxygen transport (iron-containing heme), muscle contraction (calcium), ATP processing (magnesium), production of stomach acid (chlorine), etc. Minerals are gained through diet and are needed in very small quantities, making them micronutrients.
64
What does the Michaelis-Lenten (M-M) saturation curve show?
Graph of reaction velocity vs. substrate concentration. Reveals relationship between 1/2 Vmas and Km.
65
what is Km?
Km= [S] at 1/2 Vmax.
It is the relative measure of an enzyme's affinity for its substrate. Magnitude of Km is INVERSELY proportional to substrate-enzyme binding affinity.
66
What does a low Km mean?
low Km= low affinity.
67
What is Vmax?
v = vmax[S]/(Km + [S])
It's the rate of the reaction at saturation levels of substrate.
68
why is the lineweaver burn plot?
a double inverse graph of the reaction rate (v inverted to 1/v) and substrate concentration ([s] inverted to a/[s])
69
What is the y intercept of the Lineweaver Burk plots?
1/vmax
70
what is the x intercept of the line weaver burn plots?
-1/Km
71
What is the line weaver burn plot used for ?
finding Vmax and Km experimentally
72
How can you use the Lineweaver Burk plots to identify enzyme inhibition?
Must have two trials, one with and one without inhibitor- compare result stop identify IMPACT of inhibitor on Km and Vmax.
73
Describe competitive inhibition: is it reversible? Can it be overcome? do max and Km change?
Reversible inhibition - binding AT active site so it can be overcome by increasing concentration of substrate.
VMax- no change
Km- increases
HMG-CoA reductase inhibitors used to lower cholesterol levels by inhibiting the enzyme’s function of producing cholesterol in the liver.
74
Describe uncompetitive inhibition? is it reversible? Can it be overcome? do max and Km change?
REVERSIBLE- binds only with enzyme substrate complex.
Vmax- decreases
Km- decreases
Lithium, a drug used to treat manic depression, has been shown to act as an uncompetitive inhibitor in the phosphoinositide synthesis pathway,
75
Describe Non competitive inhibition: is it reversible? Can it be overcome? do max and Km change?
REVERSIBLE- binds AWAY FROM active site. Inhibition has equal affinity for both enzyme and e-s complex.
```
Vmax= decreases
Km= no change
```
Alanine acts as a non-competitive inhibitor for the enzyme pyruvate kinase. Pyruvate kinase transfers one phosphate group from PEP (phosphoenolpyruvate) to ADP, creating pyruvate and one ATP.
76
Described Mixed inhibition; is it reversible? Can it be overcome? do max and Km change?
Inhibition has unequal affinity for ES and R, favoring one over the other.
The metal palladium is a mixed inhibitor for xanthine oxidase, an enzyme that converts xanthine to uric acid.
77
What is Irreversible inhibition?
Inhibitor binds covalently to enzyme and/or active site, disabling the enzyme for either a prolonged period of time or permanently.
The inhibitor binds the active site where it is modified in some way to irreversibly bind such that a substrate can never enter the active site. Aspirin is an example of irreversible inhibition. It binds the active sites of cyclooxygenase 1 and 2 irreversibly to prevent their inflammatory responses.
78
what phosphorylate a molecule?
kinases
79
what are 3 common disaccharides and what monosaccharide are they made of?
lactose= lactose and glucose )B-linked)
maltose= glucose + glucose
sucrose= glucose + fructose
80
How do you distinguish D- from L-?
If hydroxyl group attached to highest # choral carbon is on the RIGHT= D
on Left= L
81
what's the difference between pyranose and furanose?
6 member rings vs. 5 member ring
82
what's the difference between pyranose and furanose?
6 member rings vs. 5 member ring
83
what's an example of a 5 carbon sugar?
D-ribose
84
what's an example of a 6 carbon sugar?
D- glucose, mannose, galactose
85
What is the relationship between a-glucose vs.b -glucose?
anomers= same molecule bit different stereochemistry
86
What is difference between D glucose and L-glucose?
enantiomers
L= furthest -OH group from carbonyl on left
D= furthert -OH from carbonyl on right
87
What is the relationship between glucose and galactose?
EPIMERS- diastereomers
88
In alpha glucose, where is the C1 OH? down or up? what about in beta?
down- alpha
up- beta
89
What is difference between reducing and non-reducing sugars?
A reducing sugar is one that is capable of reducing another molecule through an oxidation-reduction reaction (the sugar will become oxidized). To be able to participate in a redox reaction, the sugar must have an open- chain form that has a free aldehyde group, and so it must be an aldose.
Nonreducing sugars will have aldehyde group.
90
How does intramolecular nucleophilic substitution work?
OH group on choral carbon (the one used to determine D/L) acts as nucleophile and attacks carbonyl carbon.
91
What is general reaction for hydrolysis of glycoside linkage?
Polymer + H2O --> Polymer (n-1) + monomer
92
Can sugars alternate between enroll and kept form?
yes
93
what's polymerization?
mono --> di --> polysaccharides
94
what is alpha linkage in polysaccharides?
linked through an oxygen that is on the OPPOSITE side of the plane from the CH2OH group (trans)
95
what is beta linkage in polysaccharides?
linked through oxygen that is on the SAME side plane as the CH2OH group. (cis)
96
what is bond in glycogen?
branched, alpha linked glucose polymer used for energy storage in animals
97
what is bond in starch?
branched alpha linked glucose polymer used for energy storage in plants.
98
what is bond in cellulose?
beta linked glucose polymer, used for energy storage in plants, indigestible to animals without help from symbiotic bacteria.
99
what are two identifying characteristics of lipids?
biomolecules and hydrophobic.
100
what are the three major ketone bodies?
1. acetoacetate
2. Acetone
3. B-hydroxybutyrate
101
All steroids are ?member ring structures.
4
102
which lipid hormone is amphiphatic ?
fatty acids (carboxylic acid is polar), phospholipids (phospho group is polar), sphingolipids (oxygen and nitrogen are polar), and glycolipids (oxygens of the sugar are polar).
103
what lipid hormones are just hydrophobic?
Triacylglycerols, steroids, terpenes, and waxes are hydrophobic and not amphipathic.
104
what is saponification?
Hydrolysis of ester
105
Tracyglycerols and phospholipids are both....?(what type of functional group?)
ESTERS -once a fatty acid attaches a glycerol= ester
106
4) Given four amino acids, Glycine, Phenylalanine, Glutamine and Aspartamine, how many unique proteins can be formed without using any amino acid more than once in any protein?
A) 8 B) 16 C) 24 D) 256
Using n! (n factorial) will also work in this case, only because each item can only be used once. The n represents the number of items and the math becomes: 4 x 3 x 2 x 1 = 24.
Gly-Phe-Glu-Asp, Gly-Phe-Asp-Glu, Gly-Glu-Phe-Asp, Gly-Glu-Asp-Phe, Gly-Asp-Glu-Phe and Gly-Asp-Phe-Glu. That is six unique chains by starting with Gly. This could be done once for each of the four amino acids, so there are 6 times 4, or 24 possible proteins.
107
what part or peptide bond cannot rotate?
C(=O) to N bond has partial double bond character and cannot rotate
108
How many residues of amino acids per turn?
3.6
109
In alph helix, where are the R groups?
R groups are sticking out of helical structure
110
What are the 4 rules of aloha helix?
1) no proline
2) no two consecutive charge amino acid
3) no two consecutive branched amino acids
4) first alpha helix turn is difficult, but the following ones have cooperative binding.
111
Would aromatic amino acids be in Beta sheet conformation or alpha helix?
excluded from beta sheets more lileyin alpha helices because they are too big --> tryptophan, phenylalanine, tyrosine, histidine.
112
What three amino acids ar more likely to be in beta sheet confirmation?
Alanine, Ser, Glycine
113
what is difference between myoglobin and hemoglobin?
one monomer versus four of O2
114
What happens to O2 binding when you run?
running --> produce lactic acid and CO2 --> pH goes down/ more acidic.
O2 is thus more easily released from the Hemoglobin and delivered to tissues - NO EFFECT ON BINDING JUST DELIVERY
115
How does BPG affect hemoglobin in high altitudes? Hb+ BPG + 4O2 -->
At high levels, pH decreases and Histidine becomes more positively charged. BPG levels go up binds positive Histidine charge and stabilize the Hemoglobin; this pushes the reaction to right, enabling better cooperatively.
116
what does the Hill coefficient do?
reflects degree of cooperativity/ allostery
117
In the equation: V={(Vmax)[s]} / {Km+[s]} , what happens when [S] >> Km ? [S]=Km ? [S] << Km ?
[S] >> Km then the velocity approaches 1
[S]=Km then velocity approaches 1/2 Vmax
[S] << Km then velocity approaches 0
118
what is another way to write Vmax based on E + S -->
Vmax= Kcat [Et] [S]
119
in the line weaver burn plot (aka double reciprocal plot0 wha tis the slope?
Km/Vmax
120
how is catalytic efficiency measured?
Kcat/ Km
121
what's a zymogen? what are the benefits?
Inactive enzyme; 1) produce active enzyme when needed 2) rapid response.
122
what is the catalytic trade of serine proteases? what does it form in an enzyme?
His57, Asp102, Ser195 --> forms specificity pocket which enable proteins to bidet through hydrogen bonding and reduce Km with cleavage to form active enzyme.
123
what are the different levels of post translational regulation?
- cleavage of zymogen
- phosphorylation, glycosylation, fatty acylation,
- allosteric modifiers- cAMP
124
what is structure of triacyglycerol?
glycerol + 3 fat acid chain
125
what is the structure of phospholipids?
glycerol or sphingosine + 1 to 2 FA + Phosphate attached to alcohol or choline.
126
what is the structure of glycolipids?
glycerol + 2Fa + mono or di saccharide + SO4
or sphingosine + 1FA + mono or oligosaccharides
+ mono or
127
Which types of proteins are extractable with detergent?
integral proteins because of hydrophobic core
128
Galactosemia in an inborn error of metabolism in which he enzyme galactose-1-phosphate uridylyltransferase (GP-UDT) is non functional, preventing the conversion of galactose to glucose. A person with this condition may not experience symptoms if they are:
a- also lactose intolerant and on restricted diet
b-diabetic and therefore insensitive to insulin
c-administered a drug that is a GP-UDT agonist
d-administered a drug that is a GDP-UDT antagonist
a
129
What does it mean for an enzyme to have 10mmol for glucose A and .2mmol KM for glucose for B ?
B will have 50% saturated at a lower concentration of glucose then glucokinase
130
Phosphoglucomutase phosphorylates glucose- 1- phosphate to form glucose 1-6 bi[hosphate. Characterization has demonstrated the a phosphorylated serine residue in the active site transfers its phosphoryl group to the substrate. The phosphorylation of glucose-1-biphosphate involves:
1) nucleophilic attack by serine hydroxyl group t carbon 1 of glucose-1-phosphate.
2) electrophilic addition of phosphate to hydroxyl group on carbon 6 of glucose 1-phosphate.
3) nucleophilic attack of glucose-1-phosphate hydroxyl group at the phosphorous of the phosphorylated serine residue.
3
131
Aspartate has a pKa of 3.7 while the structurally similar glutamate has a pKa of 4.5- why?
a) increased induction of charge in conjugate base of aspartate
b) increased induction of charge on conjugate base of glutamate
c) decreased acidity of aspartate side chain carboxylic acid.
d) increased acidity of glutamate side chain carboxylic acid.
A- inductive effect decrease with distance so more induction= more stability of conjugate base.
glutamate has one more carbon than aspartate.
132
A sample of native protein is denatured using acid. What process is observed at the molecular level after addition of the acid?
1) The acid denatures the protein by disrupting Van Der Waals forces.
2) Electronegative atoms involved in a hydrogen bonding are protonated, meting the protein.
3) the amine nitrogen abstracts a proton from the acid, increasing polarity and disrupting hydrophobic interactions
4) The carbonyl carbon is protonated, disrupting resonance of peptide bond.
2
133
which molecule is not an example of a nucleotide?
a) cAMP
b) NADH
3) UTP
4) Adenosine
nucleotide: nucleotide base + sugar backbone + nucleotide base
ADENOSINE is JUST nucleotide base.
134
Biochemical functions of water in human physiology include:
1) store and dissipate energy due to high boiling point and specific heat capacity?
2) cool body down via convection
3) solvent for metabolic reactions
4) cool body via conduction and radiation
who many of those?
I, III, IV
135
What is primary reason for excess nitrogen in urine?
Excess proteins in urine:
1) diabetes,
2) starving
3) severe damage
4) atkins diet.
136
What are hydride donors and hydride acceptors?
Specialized coenzymes such as NADH and NADPH serve as hydride donors, while NAD+ and NADP serve as hydride acceptors.
137
```
To perform the immunocytochemistry measurement, researchers dissolved an experimental antibody in aqueous solution, then added the solution to the cell culture where it bound the target p53 protein. p53 most likely associated with the antibody as a result of:
A) covalent bonds.
B) hydrophobic interactions.
C) the overlap of π orbitals.
D) hydrogen bonds.
```
Choice D is the correct answer. In general, protein-protein binding interactions, such as those interactions associated with receptor binding, antigen-antibody binding, or binding of protein subunits in quaternary structure, are the result of non-covalent interactions (e.g., hydrophobic interactions, hydrophilic interactions, electrostatic attractions and hydrogen bonds).
138
easiest way to distinguish between D and L configuration?
The easiest way to distinguish between the two is to place the most oxidized position at the top of the Fisher projection and note the position of the –OH group on either the right (D) or left (L) side.
139
what type of bonds are responsible for nucleotide base pair matching?
hydrogen and van der waals
140
Activation of an enzyme by phosphorylation of a tyrosine residue is an example of what type of enzymatic regulation?
covalent modifications
