cell phys exam 1
The process of building new cellular macromolecules is called a. Anabolism b. Catabolism
a. anabolism
Any reaction A ↔ B is at equilibrium when: a. ΔG = 0. b. ΔG°' = 0. c. [A] = [B]. d. ΔG = ΔG°'.
A. G=0
In the replication of DNA the polymerase adds nucleotides to the __ end of a primer a. 2' b. 3' c. 5'
B. 3'
The smallest unit of life is: a. a DNA molecule b. a cell. c. an organelle. d. a virus. e. a protein
B. a cell
The figure below right represents the measurements of the velocity of an enzyme catalyzed reaction with or without an inhibitor present; is this inhibition: a. Competitive b. Noncompetitive
B. noncompetitive
Living cells are always in thermodynamic _________ a. Equilibrium b. Nonequilibrium, also called "steady-state"
B. nonequilibrium also called steady state
Which of the following statements concerning procaryotes is true? a. They have no nucleus and hence no DNA. b. They have no Golgi apparatus. c. They include bacteria, yeast, and protozoans. d. They are all able to live on inorganic energy sources.
B. they have no golgi apparatus
In order to do the useful work of making new macromolecules cells generate large amounts of _______, used to do chemical work, and _________ which provides high energy electrons used for reduction reactions. a. ADP / NAD+ b. NADPH / ATP c. ATP / NADPH d. AMP / GTP
C. ATP / NADPH
Which of the following statements about the basic chemistry of cells are true? a. All cells contain exactly the same proteins. b. All proteins are constructed from the same 22 amino acids. c. All genetic instructions in cells are stored in DNA. d. All organisms contain the same genes. e. All of the above.
C. all genetic instructions in cells are stored in DNA
As a consequence, nucleic acids are synthesized a. 2' to 5' b. 3' to 5' c. 5' to 2' d. 5' to 3'
D. 5' to 3'
A nucleotide sequence is said to be palindromic if it is complementary to itself. Which of the following sequences is palindromic (self-complementary)? a. 5'-AAGCCGAA-3' b. 5'-AAGCCGTT-3' c. 5'-AAGCGCAA-3' d. 5'-AAGCGCTT-3' e. 5'-AATTGGCC-3'
D. 5'-AAGCGCTT-3'
Which of the following are examples of isomers? a. 14C and 12C b. Valine and Alanine c. Cytosine and Guanine d. D-Glucose and L-Glucose
D. D-Glucose and L-Glucose
Cells can use ATP to a. Drive conformation change, for example, in motor proteins b. Drive thermodynamically unfavorable reactions. c. Phosphorylate proteins to inactivate them. d. All of the above
D. all of the above
Reactions that have positive standard free energy changes (ΔGo' > 0) can be made to occur in cells by: a. Coupling them with exergonic reactions via a common intermediate. b. Manipulating the concentrations of products and reactants such that ΔG < 0. c. Coupling them to the hydrolysis of ATP. d. All of the above
D. all of the above
. What unit of length would you generally use to give the measurements of a typical human cell? a. Centimeters. b. Nanometers. c. Millimeters. d. Micrometers.
D. micrometers
For which of the following would you use an electron microscope rather than a light microscope? a. To pick out individual human cells from a cell culture in order to grow new cultures from them. b. To watch organelles move inside a cell. c. To look at cells stained with fluorescent dyes. d. To see ribosomes. e. To study moving bacteria.
D. to see ribosomes
In the figure, the approximate Km and Vmax of the uninhibited reaction are: a. Km = 2 mM, Vmax = 1 umole/min b. Km = 1 umole/min, Vmax = 2 mM
a. 2mM, Vmax=1 umole/min
Membrane lipids are ________ molecules because one end of the molecule is _________ while the other end is ____________ a. Amphipathic / hydrophobic / hydrophilic b. Amphibolic / large /small c. Water soluble / hydrophilic / hydrophilic d. Water soluble / hydrophobic / hydrophobic
a. Amphipathic / hydrophobic / hydrophilic
The biosynthetic pathway for the two amino acids E and H is shown schematically to the right. After showing that E inhibits Enzyme 6, and H inhibits Enzyme 3 you predict that Enzyme 1 will be most efficiently controlled via feedback inhibition by molecule: a. C b. E c. H d. E and H
a. C
Proteins can be modified by reaction with acetate resulting in the addition of an acetyl group to lysine side chains as shown below. The bond indicated in the box is most like: a. a peptide bond. b. an ester bond c. a phosphoanhydride bond. d. a hydrogen bond. e. a phosphodiester bond
a. a peptide bond
All of the following are basic properties of all cells, except: a. Cells have nuclei and mitochondria b. Cells have a genetic program and the means to use it. c. Cells are capable of producing more of themselves. d. Cells are able to respond to stimuli
a. cells have nuclei and mitochondria
You two have identified mutants of an enzyme that catalyzes a commercially useful reaction. Both mutants have the same Vmax as the original or wild type (WT) enzyme. However, one mutant has a lower Km for substrate than the WT, the other has a higher Km for substrate. Which mutant is likely to be a "better" (i.e., faster) enzyme for catalyzing the reaction: a. Neither. Since they have the same Vmax they will have the same reaction velocities at all substrate concentrations b. The lower Km enzyme since it will show greater reaction velocities at low concentrations of substrate c. The higher Km enzyme since it will show greater reaction velocities at higher concentrations of substrate.
b
Which of the following statements about enzymes are correct? a. Enzymes enable energetically unfavorable reactions (ΔG > 0) to occur. b. An enzyme preferentially binds the transition state of the reaction. c. An enzyme can typically catalyze many chemically different reactions. d. An enzyme can bind to many structurally unrelated substrates. e. Enzymes are permanently altered after catalyzing a reaction.
b. an enzyme preferentially binds the transition state of the reaction
If the coloring of calico cats is due to X chromosome inactivation, which of the following will not be true? a. Calico cats with identical patterns will be rare b. Calico cats can be male or female c. Patches of the same color represent cells that share a common lineage
b. calico cats can be male or female
DNA is negatively charged at physiological pH. A protein Z binds to DNA through noncovalent ionic interactions involving lysines. What will be the effect of acetylation of the lysine side chains (see Figure above) in protein Z on the strength of this binding: a. It should increase it because the acetylated lysine will form a greater number of ionic interactions with DNA. b. It should decrease it because the acetylated lysine will form fewer ionic interactions with the DNA. c. It should have no effect because the unmodified lysine would not have formed an ionic interaction with the DNA. d. It should have no effect because the bond formed between lysine and the acetyl group still has a positive charge.
b. it should decrease it because the acetylated lysine will form fewer ionic interactions with the DNA
Cellular membranes are composed of a. lipid bilayers held together by covalent bonds between phospholipids b. lipid bilayers held together by noncovalent interactions c. micelles held together by covalent bonds between phospholipids d. micelles held together by noncovalent interactions
b. lipid bilayers held together by noncovalent bonds
The most reliable feature distinguishing a eucaryotic cell from a procaryotic cell is: a. the presence of a plasma membrane. b. the presence of a nucleus. c. the eukaryotic cell's larger size. d. the presence of internal membranes. e. the presence of DNA.
b. the presence of a nucleus
In the DNA double helix a. Purines pair with purines b. The strands are antiparallel c. The phosphodiester bonds are 5' and 2' d. Uracil is used in place of thymine
b. the strands are antiparallel
You are studying a biochemical pathway that requires ATP as an energy source. To your dismay, the reactions soon stop, partly because the ATP is rapidly used up and partly because an excess of ADP builds up and inhibits the enzymes involved. You are about to give up when the following table from a biochemistry textbook catches your eye and you see an easy way to regenerate ATP from ADP to allow your reaction pathway to continue. Which of the following reagents are most likely to revitalize your reaction? a. A vast excess of ATP. b. Glucose 6-phosphate and enzyme E. c. Creatine phosphate and enzyme A d. Pyrophosphate and enzyme D.
c. creatine phosphate and enzyme A
Which of the following statements is correct? a. All eukaryotic cells contain chloroplasts b. No eukaryotic cells contain chloroplasts c. Eukaryotic cells acquired mitochondria before they acquired chloroplasts d. Eukaryotic cells acquired chloroplasts before they acquired mitochondria
c. eukaryotic cell acquired mitochondria before they acquired chloroplasts
Assembling the individual enzymes required for a multistep process into a protein machine is likely to increase the efficiency with which the entire process is carried out in all of the following ways EXCEPT: a. by increasing the rate at which the individual enzymes encounter their substrates. b. by ordering the reactions sequentially. c. by increasing the Vmax of the individual enzymes. d. by coordinating the regulation of the individual enzymes. e. by coordinating the movement of the enzymes.
c. increasing the Vmax of the individuals enzymes
Which of the following statements is true? a. Peptide bonds are the only covalent bonds that link amino acids together in proteins. b. The polypeptide backbone of some proteins is branched. c. Nonpolar amino acids tend to be found in the interior of proteins. d. The sequence of the atoms in the polypeptide backbone varies between different proteins
c. nonpolar amino acids tend to be found in the interior of proteins
DNA differs from RNA in: a. the number of different bases used. b. the number of phosphates between the sugars in the sugar-phosphate backbone. c. one of the pyrimidines used. d. one of the purines used. e. the chemical polarity of the polynucleotide chain.
c. one of the pyrimidines used
You have identified a mutation in a G protein that causes the G protein to remain "active" much longer than normal. Which of the following might be the explanation for this: a. The mutant G protein hydrolyzes GTP much more slowly than the normal G protein. b. The mutant G protein can no longer interact with another protein that stimulates the binding of GTP c. The mutant G protein can no longer interact with another protein that stimulates it's hydrolysis of GTP d. Both a and c.
d. both a and c.
Which of the following is NOT a component of a nucleotide? a. Ribose b. Phosphate c. Adenine d. Choline
d. choline
A common means of providing energy to an energetically unfavorable reaction in a cell is by: a. generation of a higher temperature by the cell. b. transfer of a phosphate group from the substrate to ADP. c. enzyme catalysis of the reaction. d. coupling of ATP hydrolysis to the reaction. e. coupling of the synthesis of ATP to the reaction
d. coupling of ATP hydrolysis to the reaction
Which of the following is not true of Nucleosomes a. They contain histones H2A, H2B, H3 and H4 b. The DNA is wrapped around the histone core almost 2 times c. The histone core contains a total of 8 proteins d. Histones are acidic proteins so that they can interact well with DNA
d. histones are acidic proteins so that they can interact well with DNA
The α helix and β sheet are common secondary structures in proteins, both structures are stabilized by: a. hydrogen bonding between the amino acid side chains most commonly found in proteins. b. covalent interactions between amino acid side chains and the polypeptide backbone. c. ionic interactions between charged amino acid side chains. d. hydrogen bonding between atoms of the polypeptide backbone.
d. hydrogen bonding between atoms of the polypeptide backbone
Which of the following statements is false? a. All protein molecules function by binding specifically to other molecules. b. Many proteins can bind to more than one ligand. c. Binding between protein and ligand generally involves noncovalent bonds. d. Proteins are designed to bind their ligands as tightly as possible.
d. proteins are designed to bind their ligands as tightly as possible
Embryonic stem cells have great potential for treating disease. Which of the following statements about mammalian embryonic stem cells is true? a. Under appropriate stimulation they can differentiate into different cell types b. They can be created from somatic cells from an individuals and a donor egg cell c. The generation of human embryonic stem cells is currently quite labor intensive and complicated by ethical and legal restrictions. d. Embryonic stem cells are derived from cells in the interior of the blastocyst at the earliest stage of development. e. All of the above
e. all of the above
