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BC 351
exam 1
| Question | Answer |
|---|---|
| The key properties of water molecules important for the existence of cells on earth include | its ability to form hydrogen bonds. |
| Relative to the earth’s crust, cells contain | a much higher proportion of C. |
| The electronegativity of an atom refers to | how strongly it attracts and holds electrons. |
| Which of the following bonds/interactions involves sharing electrons? | Covalent bonds |
| Electronegativity means | The ability of an atom to attract a bonding pair of electrons |
| A variable in a cell is constantly being broken down and synthesized. This situation is referred to as | dynamic steady state |
| The main cellular energy carrier is | Adenosine triphosphate |
| Noncovalent bonds and interactions | in most cases are affected by the aqueous environment. |
| The pH of household bleach is | close to 13 |
| Which of these intermolecular interactions depend on water | hydrophobic forces |
| Which of the following noncovalent bonds/interactions requires water to exist? | hydrophobic forces |
| When oxygen forms a covalent bond with carbon the both electrons are associated disproportionately with the oxygen. This means oxygen is | More highly electronegative |
| The change in Gibbs free energy (deltaG) of a reaction | refers to the energy that is available for work. |
| Humans maintain a nearly constant level of hemoglobin by continually synthesizing and degrading it. This is an example of a(n): | dynamic steady state. |
| Which of the following is not a major cellular energy currency? | ATP |
| Which of the following is the strongest non-covalent interaction? | Ionic bonds |
| The pH of a sample of blood is 7.4, while gastric juice is pH 1.4. The blood sample has: | a million times lower [H+] than the gastric juice. |
| Which of the following as a single bond is the strongest bond? | Covalent bond |
| Dynamic steady state refers to | The balanced synthesis and degradation of a molecule in a cell |
| Most generally, cancer cells | have changes that result in the breakdown of regulation of proliferation. |
| Currently, cancers are classified | by the apparent tissue/cell type of their origin. |
| Recent anticancer drugs like Gleevec | are inhibitors of enzymes that function to promote cell proliferation. |
| Anticancer drug design and development | is based upon drugs having shapes and functional groups complementary to clefts in key enzymes. |
| Cancer cells are characterized by | Rapid growth and proliferation |
| Anticancer drugs design is | Becoming more specific to key enzymes that are dysregulated in cancer cells |
| Due to the partial double bond character of the peptide bond between amino acid residues | the amide bond has a planar structure. |
| The key properties and structure of peptide bonds include | planar structure. |
| Which of the following is correct with respect to the amino acid composition of proteins? | Proteins with different functions usually differ significantly in their amino acid composition. |
| The most important contribution to the stability of a protein’s conformation appears to be the | entropy increase from the decrease in ordered water molecules forming a solvent shell around it. |
| the three classifications of amino acids includes | polar, nonpolar, and charged/special |
| alpha helix hydrogen bonds: | are roughly parallel to the axis of the helix. |
| Of the 20 standard amino acids, only ___________ is not optically active. The reason is that its side chain ___________. | glycine; is a hydrogen atom |
| Which of the following is correct with respect to the amino acid composition of proteins? | Proteins with different functions usually differ significantly in their amino acid composition. |
| At pH 7.0, converting a proline to hydroxyproline, will have what effect on the overall charge of the protein containing it? | it will stay the same |
| Amino acids are classified by | the properties of their R groups |
| Which of the following best represents the backbone arrangement of two peptide bonds? | Cα—C—N—Cα—C—N |
| A hydrophobic amino acid R group (side group) would most likely be found in a protein | on the inside of the folded chain, away from the water. |
| An amino acid residue commonly found in the middle of beta turn are | proline and glycine |
| The major reason that antiparallel β-stranded protein structures are more stable than parallelβ-stranded structures is that the latter: | have weaker hydrogen bonds laterally between adjacent strands. |
| For amino acids with non ionizable R groups, at any pH below the pI of the amino acid, the population of amino acids in solution will have: | a net positive charge. |
| Which two amino acids differ from each other by only one atom? | Ser and Cys |
| the incidence of cancer increases dramatically with age due to | the time it takes to accumulate approx 6 changes in the cell |
| Age dependent increase in death rate slows for breast and cervical cancers, but not in colon after age 50 due to | menopause |
| The process of anticancer drug discovery | recently has begun to employ compound libraries produced through combinational chemistry |
| Drug resistance is a constant problem in anticancer therapy that can be addressed by | giving patients multiple drugs that inhibit two or three oncoproteins found in a particular cancer |
| Organic chemistry reactions carried out in the top ocher labs are not much different from that occurring in living cells | false |
| carbon compound functional groups | have properties largely determined by how they interact with water molecules |
| For a reaction A<->B starting with delta G=0, what will happen if the enthalpy of B is decreased 2X relative to A | There will be more B than A |
| For a reaction A<->B starting with delta G=0, what will happen if the entropy of B is decreased 2X relative to A | There will be more A than B |
| For a rxn A<->B, with [A] 3X [B] in the cell (at homeostasis) and delta G knot=0 | Delta G will be negative |
| Interactions between two H molecules bonded to two different carbons will be mediated by | Van Der Walls |
| Interactions between a N molecule and H bonded to a carbon will be mediated by | Van Der Walls |
| Interactions between a N and H bound to an O will be mediated by | hydrogen bonds |
| Interactions b/w two H bound to two different carbons will be driven by | hydrophobic interactions |
| Phosphoric acid is tribasic, with pka's at 2.14, 6.86, and 12.4. The ionic form that predominated at pH 3.2 is | H2PO4- |
| Amino acids | found in cells are generally restricted to the 20 common AA |
| The polar/nonpolar nature of amino acid R groups are difficult to measure using free amino acids | as a result of the polar amino and carboxyl groups found on each amino acid |
| the polar/nonpolar nature of amino acid R groups are difficult to measure using free AA, you can get around this problem by | measuring the solubility of the R groups alone in water and organic solvent. |
| Which of the following statements about aromatic amino acids is correct? | On a molar basis, tryptophan absorbs more UV light than tyrosine |
| Titration of valine by a strong base reveals two pK's. The titration run at pk2 is | (NH3+) + (OH-) --> (NH2-) + (H2O) |
| Protein and nucleic acids | are both large polymers |
| The production of just one molecule of each AA sequence of polypeptides 300 AA in length will require more atoms than exists in the universe | True |
| The functional differences between two different enzymes of E. coli result directly from their different | AA sequences |
| Which of the following pairs of bonds within a peptide backbone show free rotation | Ca-C and N-Ca |
| What is the proper definition of equilibrium with respect to a biochemical reaction | there is no net change in reactant and product concentrations |
| Given that all 20 AA have at least two oppositely charged, ionizable R-groups, which statement is incorrect? | It is not possible to fully deprotonate amino acids |
| Protein folding to a native conformation is highly dependent upon the following, except | the rotation about the peptide bond |
| On a ramachandran plot | the dihedral angles of the alpha carbon to carbonyl carbon covalent bond and the alpha carbon to nitrogen covalent bond allowed in various tripeptides are displayed |
| an alpha helix would be destabilized most by | the presence of two Lys (+ charge) residues near the amino terminus of the alpha helix |
| Which is the more stable beta sheet- anti parallel or parallel | Antiparallel due to linear hydrogen bonds |
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potato80