An amino acid in a medium with a pH above its isoelectric point would have
a net negative charge
Twice as much enzyme is used
Vmax doubles, Km no change
Half as much enzyme is used
Vmax is half as large, Km no change
a competitive inhibitor is present
Vmax no change, Km increases
An uncompetitive inhibitor is present
Vmax decreases, Km decreases
The most abundant metals in human body are
Na, K, Ca
Which pair of amino acids may form an ionic interaction through their side chains?
Glu, Arg
What statement about hydrogen bonds is FALSE?
Hydrogen bonds are covalent bonds between Hydrogen and Oxygen in a water molecule
What type(s) of inhibition can be reversed?
(All of the above) Competitive, Uncompetitive, Noncompetitive
At equilibrium, the Gibb's free energy is
Zero
The pH of a sample of blood is 7.4; the pH of a sample of gastric juice is 1.4. The blood sample has an [H+]
a million times lower than that of the gastric juice
What is the [A−]/[HA] ratio when the weak acid is in a solution one pH unit above its pKa?
10:1
Which of the reactions will take place spontaneously?1. A→B ΔG= -10 kJ/mol2. C→D ΔG= 10 kJ/mol
Reaction 1 (A→B ΔG= -10 kJ/mol)
Estimate the net-charge of the peptide at pH 12.0Thr-Glu-Pro-Ile-Val-Ala-Pro-Met-Glu-Tyr-Gly-Lys
-4
Rank cell components from smallest to largest
proton, h2o, amino acid, protein, ribosome, mitochondrion, cell nucleus
The energy of activation is:
the difference in free energy between the substrate and the transition state
Which pair of amino acids has two chiral centers?
Ile and Thr
Match object with it's size ribosomebacterial cell (ecoli)yeast cellskin celltardigrade
30 nano m2 micro m10 micro m30 micro m0.5 mm
Match the term with the proper descriptionenzymesubstrateactive sitetransition siteinduced fit
Protein catalystReactant in an enzyme-catalyzed reactionSite on the enzyme where catalysis take placeThe least stable reaction intermediateChange in enzyme structure on substrate binding
In competitive inhibition, an inhibitor
binds reversibly at the active site
The enzyme Hexokinase catalyzes the phosphorylation of six-carbon sugars. The Km for hexokinase with glucose is 0.15 mM. The Km for hexokinase with fructose is 1.5 mM. Which substrate does hexokinase bind more strongly?
Glucose
A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro-Gly-. This sequence is most probably part of a(n)
β-turn
What is pI (Isoelectric point)?
The pH at which a solute has no net electric charge and does not move in an electric field
Which group of amino acids would be MOST likely to be found in the core of protein that is folded into a three-dimensional structure and soluble in water?
Isoleucine, Alanine, Valine
A small molecule that DECREASES the activity of an enzyme by binding to a site other than the catalytic site is termed a(n)
allosteric inhibitor
Enzyme Fructokinase catalyses the reaction of phosphorylation of fructose
transferases
Tyrosine has three ionizable groups with pKa(-COOH) = 2.2; pKa (-NH3+) = 9.11; and pKa (-R) = 10.07. In which pH ranges will this amino acid have the greatest buffering capacity?
at pH's between 9 and 10
Which group cointains only amino acids with a hydroxyl group on their side chain?
Tyr, Ser, Thr
For the peptide Glu-Met-Arg-Thr-Gly, name the carboxyl-terminal residue
Glycine
Scurvy is a deficiency of [a]which is required for [b].
Scurvy is a deficiency of Vitamin C which is required for collagen synthesis
T/F: Kcat = Vmax/[Enzyme]
True
Which of the following is true about the properties of aqueous solutions?
Hydrogen bonds form readily in aqueous solutions
What is NOT true about Prokaryotes?
Prokaryotes contain mitochondria
What value of [S], as a fraction of KM is required to obtain 20% Vmax?
0.25 KM
The aqueous solution with the highest pH is
0.1M NaOH
What is the consequence of a high KM value of an enzyme?
High concentration of the substrate should be reached for maximal enzyme activity.
When the substrate concentration is much greater than KM, the rate of catalysis is almost equal to:
Vmax
Calculate the pI of valine using the given values:pKa (-COOH)=2.3pKa (-NH2) = 9.7
6
One angstrom is equal to
10^-10 m
Which of the following peptides will have a net charge 0 at neutral pH?
Val-Ala-Leu
Which of the following is true under the following conditions: The enzyme concentration is 5 nM, the substrate concentration is 5 mM, and the KM is 5 μM
The enzyme is saturated with substrate
The peptide Ala-Glu-Gly-Ala-Leu has
four peptide bonds
We discussed several molecules that affect hemoglobin's structure upon binding to it. Match each one with its description
2,3 BPG: Binds to the "donut hole"; favors T-state-release of oxygenOxygen: Binds iron in heme group; favors R-state- more binding of oxygenCO2: Binds to hemoglobin; changes hemoglobin's structure to favor release of oxygen CO: Binds iron in heme group; favors R-state; blocking release of oxygen.
The peptide Ala-Glu-Gly-Ala-Leu has
Four peptide bonds
The structure of normal adult hemoglobin can be described as
a tetramer composed of two aB dimers
Write in one-letter code the name of the peptide below
AYDG
What three elements make up 90% of the atoms in living organisms
H,O,C
What is pl (isoelectric point)?
The pH at which a solute has no net electric charge and does not move in an electric field.
A polypeptide containing disulfide bonds is likely to be rich in which of the following amino acids
Cysteine
An amino acid in a medium with a pH below its isoelectric point would have
A net positive charge
What amino acid is not chiral
Glycine
Citric acid has three carboxyl groups. The pKa value for each of them are 3,1,4.8, and 6.4. What would be the charge on a citric acid molecule in the solution with the pH 9?
-3
Why myoglobin does not exhibit cooperatively
It only has one subunit
Which of the following is correct concerning the differences between hemoglobin and myoglobin
Hemoglobin exhibits cooperative binding of O2 while myoglobin does not
A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro_Gly-. This sequence is most probably part of a(n)
B-turn
Which of the following is true about the properties of aqueous solutions
Hydrogen bonds form readily in aqueous solutions.
Which amino acid in hemoglobin is involved in coordinating iron in addition to the heme prosthetic group
Histidine
The most abundant metals in human body are
Na,K,Ca
What is the HIGHEST level of protein structure in human insulin, which has two polypeptides of different mass linked by several disulfide bonds
quaternary
Which of the following peptides will have a net charge ) at neutral pH
Ala-Ala-Ala
The pH of a sample of bond is 7:4; the pH of a sample of gastric acid is 1.4. The blood sample has an [H+]:
a million times lower than that of the gastric acid
The aqueous solution with the highest pH is
0.1M NaoH
What is NOT true about prokaryotes
Prokaryotes contain mitochondria
Below is the scheme known as the central dogma. Each of the arrows (A,B,C) represents a particular process in gene expression. A,B, and C, respectively, are:
replication, transcription, translation
tyrosine has three ionizable groups with pKa(-COOH) = 2.2, pKa(-NH3) = 9.11, and pKa(-R) = 10.07. in which pH ranges will this amino acid have the greatest buffering capacity
at pH's between 9 and 10
Which of the following molecular patterns or processes are common to both bacteria and humans. Mark all the correct answers
-Using ATP as an "energy currency" -similar bimolecular composition-genetic information flow development of tissues
What is the [A-]/[HA] ratio when the weak acid is in a solution one pH unit above its
10:1
Assume that curve 3 corresponds to Hemoglobin with physiological concentrations of CO2 and BPG at pH 7. Which curve represents decrease in CO2
2
Angstrom equals
10^-10 m
Which group of amino acids would be MOST likely to be found in the core of protein that is folded into a three-dimensional structure and soluble in water?
Isoleucine, Alanine, Valine
Which diagram CORRECTLY represent a hydrogen bond
B and C
Which pair of amino acids may form an iconic interaction through their side chains
Glu, Arg
The molecule that competes with oxygen for the binding site on hemoglobin
Carbon Monoxide CO
What is NOT true, according course syllabus:
You can drop 1 exam grade
Cysteine is the only amino acid with sulfur in the R group
False
Estimate the net-charge of the peptide at pH 12.0:
-4
Peptide sequence is always written from the carboxyl terminus to the amino terminus
False
Which of the following is NOT correct concerning myoglobin?
The heme group is bound to the globin chain by two disulfide bonds to cysteine residues
Which group contains only amino acids with a hydroxyl group on their side chain?
Tyr, Ser, Thr
To what atom does oxygen bind in hemoglobin
Fe^2+
What statement about hydrogen bonds is FALSE?
Hydrogen bonds are covalent bonds between Hydrogen and Oxygen in a water molecule.
Big atoms with names T or F
True
Typical pKa values of ionizable groups in proteins
True