All of the self tests
What is the shortest A-helix that will span a 75 Å membrane bilayer?
50 amino acids
At what pH is the side chain of cysteine 75% ionized?
8.8
Gramicidin is an example of:
A pore forming protein.
What three types of amino acid residues are found in high proportion in collagen?
Glycine, Proline and 4-hydroxyproline.
Which of the following amino acids would serve as the best buffer at pH 6? (A) H (B) I (C) Y (D) S (E) E
H
Which of the following histone proteins is not a core component of the nucleosome?
H1
Which of the lipoproteins listed below is commonly referred to as the good cholesterol?
HDLs
The value of kcat/Km for an enzyme:
Has the units of a second order rate constant.
An essential amino acid in the active site of RNA nuclease is:
Histidine.
Which of the following statements about the Km is correct?
Km is a measure of the affinity of the enzyme for the substrate. 11
Triacylglycerols are transported in the blood stream by:
Lipoproteins.
trypsin cleaves
Lys, Arg
Which of the following reagents would be most useful in determining the N-terminal residue of a polypeptide?
Phenylisothiocyanate
Chymotrypsin catalyzes:
a ping pong Bi Bi reaction
Adenosine 5'-triphosphate is
a ribonucleotide.
Ras is:
a small G protein.
The structure of silk fibrion consists of:
antiparallel B-sheets.
Which of the following does not serve as a lipid anchor to a peripheral membrane protein?
cholesterol
Which of the following molecules can freely diffuse across biological membranes?
cholesterol
Bone is composed primarily of:
collagen
An A-helix would be stabilized by:
containing an arginine and aspartate 3 residues apart.
Secondary active transport:
couples the potential energy of an electrochemical gradient to drive an otherwise endergonic transport.
The spatial arrangement of protein subunits is called:
quaternary structure.
When the pH decreases from 7.4 to 7.2, the oxygen affinity of myoglobin
remained unchanged
Cytidine 5'-triphosphate is
ribonucleotide
Hair, finger nails, toe nails and horns are composed primarily of:
keratin
Gel filtration chromatography fractionates proteins based on
molecular size
Ca2+ -ATPase is an example of Oxygen absorption by muscle cells is an example of 34.) Glucose absorption by erythrocytes is an example of 35.) Gramicidin is an example of 36.) The symport of glucose and Na+ by intestinal epithelium cells is an example of 37.) Na+ ,K+ -ATPase is an example of 38.) Flippases that maintain the transverse asymmetry of the membrane are an example of
primary active transfer passive transport facilitated transport facilitated transport secondary active transport primary active transport primary active transport
H+ -gastric ATPase is an example of:
primary active transport
The sequence of amino acids in a protein is:
primary structure
Protoporphyrin consists of:
pyrrole rings linked by methylene bridges.
Biological membranes are
held together by hydrophobic interactions.
In a typical eukaryotic cell the pH is usually around 7.40, What is the hydrogen ion concentration in a typical eukaryotic cell?
(C) 4 X 10-8 M
The large dipole moment of water is due to
- the electronegativity of Oxygen atom - waters bent geometry - the polarity of the O-H bond
A cell has an intracellular concentration of glucose equal to 1mM. The extracellular concentration of glucose is 12 mM. T=298 o K, R=8.314 J/mole o K, F=96,500 J/Vmole. What would be the change in free energy if 1 mole of glucose is transported into the cell?
-6.2kJ
A cell has an intracellular concentration of mannose equal to 0.1mM. The extracellular concentration of mannose is 2 mM. T=298 o K, R=8.314 J/mole o K, F=96,500 J/Vmole. What would be the change in free energy if 1 mole of mannose is transported into the cell?
-7.4kJ
An -helix would be destabilized by
-containing two successive charged residues. -containing two successive bulky nonpolar residues. -containing a proline residue. -containing a glycine residue.
At what pH is the side of tyrosine ½ ionized?
10.5
If a relaxed circular double-stranded DNA molecule containing 1,600 bp in the B-DNA conformation were reacted with a DNA gyrase which introduced 10 negative supercoils into this DNA molecule, what would be the linking number, L?
150
A relaxed circular double-stranded DNA molecule containing 1,600 bp is in the B-DNA conformation. What is the value of L for this molecule?
160
Calculate the pKa of Formic acid, given that when the concentration of formic acid is 0.1 M and the formate ion concentration is 0.018 M, the pH is 3.01.
3.75
What is the pH of 10-4 M HCl?
4
Calculate the pKa of a propionic acid solution, given that when the concentration of propionic acid is 0.10 M and the propionate ion concentration is 0.43 M, the pH is 5.50.
4.87
) Which of the following contributes to the structural rigidity of cellulose?
Adjacent cellulose polymers are stabilized by extensive hydrogen bonding.
The second law of thermodynamics states
All spontaneous processes increase the entropy of the universe.
Which of the following is not a glycoaminoglycan?
Amylopectin
In an A-helix, The side chains of the amino acid residues:
Are found on the outside of the helix spiral
Triacylglycerols are an excellent for storage of metabolic energy because they:
Are highly reduced.
G proteins:
Are inactive when bound to GDP.
If the following polypeptide were folded into an A-helix, to which amino acid would the carbonyl of cysteine be hydrogen bonded? Cys-Tyr-Ile-Gln-Asp-His-Ala
Aspartate
You want to study an enzyme reaction at pH 4.0. Which of the following weak acids would make the best buffer solution for this pH based on the given Ka values? (A) Phosphoric Acid Ka = 7.3 X 10-3 (B)Lactic Acid Ka = 1.4 X 10-4 (C)Acetic acid Ka = 1.7 X 10-5 (D)H2PO4 - Ka = 6.3 X 10-8 (E) Bicarbonate Ka = 6.3 X 10-11
B
Which of the following statements is correct? (A) The A-helix is composed of more than one polypeptide chain. (B) B-Sheets are found in nature only in the antiparallel form. (C) The A-helix is stabilized by successively charged amino acids. (D)B -sheets are stabilized primarily by ionic interactions between the side chains of amino acids. (E) B-turns often contain proline residues
B-turns often contain proline residues
Due to the short half life of hormones, how can the circulating hormone concentration be kept constant under normal conditions?
By maintaining constant rates of hormone synthesis and degradation.
What three types of amino acid residues are found in high proportion in silk fibroin?
Glycine, Alanine and Serine. (GAS)
Cytosine has an amino group at the
C4 position
Adenine has an amino group at the
C6 position
Chymotrypsin cleaves at
CT of F W Y
elastase cleaves
CT of Gly, Ala
Carboxypeptidase cleaves
CT until Pro
Protein Kinase C is activated by
Calcium ions and Diacylglycerol.
Hemoglobin carries CO2 from the tissues back to the lungs by:
Carbamylation of N-terminals of the 4 polypeptide chains.
Plasmids are
Closed circular extrachromosomal DNA molecules.
A transition state analog would serve as an effective:
Competitive inhibitor
The primary reason phospholipids are the main constituents of cell membranes is related to the fact they:
Contain both a polar and a nonpolar region.
ADP:
Contains a furanose ring
In both hemoglobin and myoglobin, the role of the proximal histidine is to:
Coordinate to the heme iron.
Which one of the following is NOT a direct action of insulin binding to the insulin receptor? (A)Activation of the tyrosine kinase activity of the B-subunit of the receptor. (B) Cross phosphorylation of the cytostolic domains of the B-subunit of the receptor. (C) Phosphorylation of target proteins. (D)Activation of adenylate cyclase. (E) Increased activity and number of glucose transporters in the cell membrane.
D
Facilitated diffusion through a biological membrane is:
Driven by a difference in solute concentration
Facilitated diffusion through a biological membrane is:
Driven by the difference in solute concentration
Ruptured biological membranes are self-sealing due to all of the following except: (A)The amphipathic character of the lipids. (B) The hydrophobic interactions between the lipids. (C) The fluidity of the membrane. (D)The increase in entropy of the system upon resealing. (E) The covalent linkages between adjacent lipids.
E
The Na+ ,K+ ATPase (A)is an example of active transport. (B) mediates the antiport of Na+ and K+ . (C) is an example of an integral protein. (D)generates an electrochemical gradient. (E) all of the above statements are true.
E
Which lipid does not contain a sphingosine backbone? (A)Ganglioside GM3 (B) Choline sphingomyelin (C) Ceramide (D)Galactosyl Cerebroside (E) Phosphatidylinositol.
E
Cholesterol is phospholipid
F
T/F A lipposome is an enzyme that hydrolyzes phospholipids.
F
T/F The binding of oxygen in hemoglobin or myoglobin, oxidizes the heme iron from the Fe2+ to the Fe3+ state.
F
T/F The insulin receptor is a 7-TMS receptor.
F
Glycogen is a polymer composed of which of the following?
Glucose
which of the following is an example of secondary active transport?
Glucose transport by intestinal epithelium cells.
Which of the following amino acids is most soluble in water at pH 7.0?
Glutamate
Which of the following statements about hydrogen bonds is true?
Hydrogen bonds account for the high boiling point of water.
Which of the following rank the interactions in order of strength from the lowest to the highest?
Hydrophobic interactions, hydrogen bonds, ionic interactions, covalent bonds.
Which of the following statements is correct? (A)Parallel B-sheets are more stable than antiparallel B-sheets. (B) In B-sheets,every carbonyl oxygen is hydrogen bonded with an amide hydrogen four residues farther up the polypeptide chain. (C) Only antiparallel B-sheets are found in proteins. (D)All B-sheets have a left-handed twist. (E) In all B-sheets successive side chains of the polypeptide chains occur on opposite planes of the sheet.
In all B-sheets successive side chains of the polypeptide chains occur on opposite planes of the sheet.
Increasing the pH from 7.2 to 7.4 would:
Increase the O2 binding affinity of hemoglobin.
A lack of insulin causes:
Increased production of B-hydroxybutyrate.
A competitive inhibitor:
Increases the apparent Km with no effect on the Vmax.
2,3, bisphosphoglycerate:
Increases the p50 of hemoglobin.
If you took off last Wednesday evening leaving TAMU elevation near sea level and went to party at the Octoberfest in the rockin' ski lodge town of Park City, Utah elevation 10,000 feet (beautiful this time of year). Your body would adapt to the lower oxygen concentration by,
Increasing the BPG concentration.
How can the organism rapidly change the concentration level of circulating hormones?
Increasing the rate of hormone synthesis and inhibiting the rate of degradation, or by increasing the rate of degradation while decreasing the rate of hormone synthesis.
2,3 Bisphosphoglycerate:
Is bound to hemoglobin primarily through electrostatic interactions.
What is the advantage of adding SDS to gel electrophoresis?
SDS allows proteins to be separated on the basis of approximate mass
T/F )Antiparallel B-sheets are more stable than parallel B-sheets
T
T/F B-turns often contain proline residues.
T
T/F Cellulose is held together by intermolecular hydrogen bonds.
T
T/F Glucagon is the hormone that signals low concentration of glucose in the blood.
T
T/F Glycogen is a branched polymer consisting of alpha(1 to 4) and (1 to 6) glycosidic linkages.
T
T/F Histones are basic proteins rich in lysine and or arginine.
T
T/F The glucagon receptor is a 7 transmembrane segments receptor.
T
Which of the following statements regarding the Ca2+ Pump of the sacroplasmic reticulum is incorrect?
The Ca2+ Pump is an example of secondary active transport.
What is the importance of the rapid inactivation of circulating hormones?
The ability to rapidly react to changing metabolic conditions
Which of the following is not a cellular mechanism for regulating enzyme activity?
The binding of regulatory proteins via disulfide bond formation.
In an A-helix, the hydrogen bonding interaction involves which atoms or groups?
The carbonyl C=O of residue number, n, with the amide NH of residue n + 4.
A clathrate is
The extensive hydrogen-bonding network of liquid water molecules around
All of the following statements about the plasma membrane of typical mammal cell are true EXCEPT:
The fluidity of the membrane is maintained as the temperature is lowered by adjusting the saturated fatty acid composition of the phospholipids.
As oxygen binds to the Hb subunits:
The iron atom moves into the plane of the heme to trigger the T to R transformation.
You are trying to separate the following 3 tripeptides by anion exchange chromatography. (a) Gly-Pro-Val, (b) Ser-Asp-Met and (c) Ala-Lys-His. If the pH is 7.0, then:
The order of elution would be c-a-b.
Which one of the following statements concerning the binding of oxygen by hemoglobin is correct?
The oxygen affinity of hemoglobin increases as the per cent saturation increases.
What is the source of the cooperativity of hemoglobin?
The quaternary interactions between subunits
The most important biological function of the distal histidine of hemoglobin is:
To decrease the affinity of the heme for carbon monoxide.
Which of the following is not a component of biological membranes?
Triacylglycerols
The structure of collagen consists of:
a triple helix with every third residue a glycine residue facing the interior of the helix.
Certain malignant tumors of the pancreas cause excessive production of insulin by the B-cells. Affected individuals exhibit shaking, trembling, weakness, fatigue, sweating and insatiable hunger. (a.) What is the effect of hyperinsulinism on the metabolism of carbohydrate, amino acids and lipids by the liver? (b.) What are the causes of the observed symptoms?Why does this condition if untreated result in brain damage?
a. Excessive utilitization of blood glucose by the liver leading to hypoglycemia. Insulin shuts down fatty acid catabolism and protein amino acid catabolism. b.All of the observed symptoms are caused by low levels of ATP because there is very little circulating fuels in the blood stream. Hyperinsulinism causes a severe decrease in blood glucose which causes lack of brain function leading to brain damage, coma and brain death
Which of the following statements about hemoglobin is correct? (A)The symmetry of the protein is maintained in the T to R transition. (B) Due to the interactions between subunits, the whole tetramer must simultaneously convert from the T to R transition. (C) There are two sets of hydrogen bonds and salt bridges, one set stabilizes the T-state the other set stabilizes the R-state. (D)In the absence of oxygen, the T-state is favored.
all
Which of the following pairs is interconverted in the process of mutarotation
alpha- D-glucose and Beta-D-glucose
When the pCO2 increases from 10 to 40 torr, the oxygen affinity of hemoglobin
dec.
at equilibrium
delaG = 0
Under the biochemistry standard conditions:
delta G = delta G0'
Which of the following is not a state function: (A) Pressure (B) Heat (C) Enthalpy (D) Entropy (E) Free Energy
heat
Ion exchange chromatography fractionate proteins based on
electrostatic charge
If heat energy is absorbed by the system during a spontaneous chemical reaction, the reaction is said to be
endothermic and exergonic.
If a reaction produces heat but is not spontaneous then it is
exothermic and endergonic
Which of the following is a ketose? (A) Mannose (A) Galactose (B) Fructose (C) Ribose (D) Threose
fructose
Which of the following is the C-4 epimer of glucose?
galactose
A peptide bond:
has partial bond character
For any amino acid with a neutral side chain, at any pH below the pI of the amino acid, the amino acid will
have a net positive charge.
The portion of a transmembrane protein that is located within the plasma membrane is most likely to be composed of amino acids that are:
hydrophobic
The folded states of globular proteins in aqueous solutions are stabilized mainly by:
hydrophobic interactions
HCO3- is ___________ to biological membranes. Testosterone is __________ to biological membranes. Galactose is _______________ to biological membranes. O2 is ___________ to biological membranes
impermeable permeable impermeable permeable
If the pH decrease from 7.4 to 7.3, the p50 of hemoglobin would
inc.
When a glutamic acid residue is brought into close proximity to an aspartate residue the pKa of the glutamic acid residue
inc.
When a glutamic acid residue is shifted from the surface of a protein into a hydrophobic, nonpolar pocket in the interior of the protein, the pKa of the glutamic acid
inc.
When a histidine residue is brought into close proximity to an aspartate residue the pKa of the histidine
inc.
When the concentration of BPG decreases, the oxygen affinity of hemoglobin
inc.
When the pH increases from 7.2 to 7.4, the oxygen affinity of hemoglobin
inc.
When an enzyme is inhibited by a competitive inhibitor, the inhibition can be overcome by:
increasing the concentration of substrate.
The free energy change, deltaG
is equal to zero at equilibrium
The Km is:
numerically equal to the substrate concentration that produces half-maximal velocity
The fatty acid designated by (18:1^9 ) is
oleic acid
In the capillaries of respiring tissues, carbon dioxide is released by muscle cells. This is an example of
passive diffusion
In the capillaries of respiring tissues, carbon dioxide passes through the plasma membrane into the erythrocyte cell. This is an example of:
passive diffusion
13.) Carbon dioxide is __________ to biological membranes. 14.) Glucose is __________ to biological membranes. 15.) Na+ is _____________ to biological membranes. 16.) Ethanol is__________e to biological membranes . 17.) Cl- is______________ to biological membranes.
permeable impermeable impermeable permeable impermeable
Water derives all its special properties from its
polarity and H-bonding capacity
The activation of Phospholipase C causes all of the following EXCEPT: (A)The cleavage of membrane bound phosphatidylinositol 1,4,5 trisphosphate. (B) The production of diacylglycerol. (C) The release of calcium ions from the endoplasmic reticulum. (D)The activation of calmodulin dependent protein kinases. (E) The activation of adenylate cyclase
the activation of adenylate cyclase
The slowest step of protein folding is
the conformational adjustments to optimize the orientation of the side chains.
When the pH equals the pKa of a weak acid, then:
then the conc. of weak acids and conj. base are equal
Which of the following is not a state function? (A)volume (B) entropy (C) free energy (D)internal energy (E) thermal energy
thermal energy
The base located at the 5'-end is
thymine
The 20 amino acids found in proteins are all L-amino acids. (A) True (B) False
true
Z-DNA
typically has alternating GC residues.
