Exam 1

Which two of the following elements are major components of organic molecules? -bromine -calcium -oxygen -nitrogen -molybdenum

How many single covalent bonds does each of the following generally form? carbon hydrogen

molecular formula of carboxyl group and hydroxyl group?

Nucleic acids are polymers of what?

Proteins are polymers of what?

Polysaccharides are polymers of what?

Which of the following constituents found in eukaryotic cells are correctly ranked from largest to smallest? -cell nucleus > mitochondrion > ribosome > water molecule > protein > amino acid > proton -mitochondrion > cell nucleus > ribosome > water molecule > protein > proton > amino acid -proton > water molecule > amino acid > protein > ribosome > mitochondrion > cell nucleus -cell nucleus > mitochondrion > protein > amino acid > water molecule > ribosome > proton -cell nucleus > mitochondrion > ribosome > protein > amino acid > water molecule > proton

For each molecule below, specify the polarity of the bonds and the overall polarity of the molecule. Cl-Be-Cl and H-O-H

If a solid line represents a covalent bond and a dotted line represents intermolecular attraction, which of these choices shows a hydrogen bond? Check all that apply. -D...H-F- H-H -O...H-C- -N...H-O-

Which three of the following statements are true? -The bilayer of a cellular membrane is primarily composed of amphipathic (amphiphilic) lipids. -The tendency of hydrophobic molecules to aggregate in water is called the hydrophobic effect. -Forming an ordered network of water around hydrophobic molecules increases the entropy of water. -Nonpolar molecules that have no polar groups (e.g. hydrocarbons) can readily form micelles. -Placing a hydrophobic molecule into water causes water molecules to orient themselves around it.

Complete the following equation for the ionization of water by drawing the conjugate acid and conjugate base. Include lone pairs of electrons. H2O + H2O ->

Calculate either [H3O ] or [OH-] for the solutions below at 25 °C. Is the solution basic at 25 degrees Celcius? [OH-] = 2.93 * 10^-7 M

Calculate either [H3O ] or [OH-] for the solutions below at 25 °C. Is the solution basic at 25 degrees Celcius? [H30+] = 9.97 *10^-9

Calculate either [H3O ] or [OH-] for the solutions below at 25 °C. Is the solution basic at 25 degrees Celcius? [H30+] = 0.000705 M

Determine the dissociation constants for the following acids. Express the answers in proper scientific notation where appropriate. Is it a strong or weak acid? pKa = 3.0

Determine the dissociation constants for the following acids. Express the answers in proper scientific notation where appropriate. Is it a strong or weak acid? pKa = 8.10

Determine the dissociation constants for the following acids. Express the answers in proper scientific notation where appropriate. Is it a strong or weak acid? pKa = -1.0

What is the pH of an aqueous solution with a hydrogen ion concentration of [H ] = 6.8 × 10-3 M?

What is the hydroxide ion concentration, [OH-], in an aqueous solution with a hydrogen ion concentration of [H ] = 6.8 × 10-3 M?

The equilibrium concentrations of the reactants and products are: [HA] = 0.210 M [H ] = 3.00 × 10-4 M [A-] = 3.00 × 10-4 M Calculate the Ka value for the acid HA.

How does a buffer resist change in pH upon addition of a strong acid? -The strong acid reacts with the weak acid in the buffer to form a weak base, which produces few H ions in solution and therefore only a little change in pH. -The strong acid reacts with the weak base in the buffer to form a weak acid, which produces few H ions in solution and therefore only a little change in pH. The strong acid reacts with the strong base in the buffer to form a salt which, produces few H ions in solution and therefore only a little change in pH.

Which three of the following statements accurately describe the blood buffering system in humans? The blood buffering system . . . -utilizes the H2CO3/HCO3- conjugate acid/base pair. -maintains the pH of blood near 7.4. -depends on the ionization of H2PO4-. -utilizes the acetic acid/acetate conjugate acid/base pair. -regulates the blood pH at 7.4 /- one pH unit. -is facilitated by the enzyme carbonic anhydrase, which interconverts carbon dioxide and water to carbonic acid (ionizes into bicarbonate and H ).

Which form of the amino acid is in L-configuration? H +H3N-C-COO^- R OR H -^OOC-C-NH3+ R

Peptides can be separated using an ion-exchange column based on their isoelectric (pI) values. At which pH values would two different peptides, one with a pI of 6.0 and the other with a pI of 9.0, bind to a cation- and anion-exchange column? Each peptide may be capable of binding to each column at more than one pH value. Peptide A: pI = 6.0 Peptide B: pI = 9.0

A mixture of the amino acids leucine (Leu), glutamate (Glu), and arginine (Arg) is added to a cation exchange column at neutral pH. In what order will they elute from a cation exchange column? -Glu, Leu, Arg -Leu, Arg, Glu -Arg, Glu, Leu -Glu, Arg, Leu -Arg, Leu, Glu

The following statements describe SDS-PAGE, a method used to separate proteins. Select the true statements. Assume that SDS-PAGE is performed under reducing conditions. -Smaller proteins migrate faster through the polyacrylamide gel. -Sodium dodecyl sulfate binds proteins, resulting in protein-SDS complexes that are similar in size. -Proteins are separated in a polyacrylamide gel matrix. -Protein-SDS complexes migrate toward the negative electrode. -Proteins are visualized using a dye that binds to the gel matrix, but not to proteins. -Protein-SDS complexes have similar mass to charge ratios, therefore separation is by size.

Determine the highest level of protein structure described by the following. Sort each item from primary structure to quaternary structure. -overall shape of a single polypeptide unit -beta-pleated sheet -order of amino acids -alpha-helix -overall macromolecule structure containing more than one polypeptide chain

From the choices below, choose the major force controlling tertiary protein structure. -disulfide bonds -hydrophobic effect -hydrogen bonding -ion pairs -inorganic ions

Test your understanding of the term denaturation by deciding which of the following statements are true. -a denatured protein has a different tertiary structure than its native state -cooking an egg hydrolyzes its albumin -denaturation and digestion refer to the same process -digestive enzymes hydrolyze proteins -egg white meringue (made by beating egg whites) contains denatured proteins -protein denaturation involves cleavage of its peptide bonds soaking fish in lime juice (pH 2.3) denatures the proteins

Test your understanding of the term denaturation by deciding which of the following statements are false. -a denatured protein has a different tertiary structure than its native state -cooking an egg hydrolyzes its albumin -denaturation and digestion refer to the same process -digestive enzymes hydrolyze proteins -egg white meringue (made by beating egg whites) contains denatured proteins -protein denaturation involves cleavage of its peptide bonds soaking fish in lime juice (pH 2.3) denatures the proteins

Determine what four statements apply to hemoglobin. -as oxygen binds to this molecule, the shape of the molecule changes, enhancing further oxygen binding -carbon monoxide binds at an allosteric site, lowering oxygen binding affinity -oxygen binds irreversibly to this molecule -the binding pattern for this molecule is considered cooperative -the molecule delivers oxygen more efficiently to tissues -the oxygen dissociation curve is hyperbolic in shape -the oxygen dissociation curve is sigmoidal in shape ("S"-shaped) -this molecule has a greater affinity for oxygen

Determine what two statements apply to myoglobin. -as oxygen binds to this molecule, the shape of the molecule changes, enhancing further oxygen binding -carbon monoxide binds at an allosteric site, lowering oxygen binding affinity -oxygen binds irreversibly to this molecule -the binding pattern for this molecule is considered cooperative -the molecule delivers oxygen more efficiently to tissues -the oxygen dissociation curve is hyperbolic in shape -the oxygen dissociation curve is sigmoidal in shape ("S"-shaped) -this molecule has a greater affinity for oxygen

What is the effect of a negative modifier (effector) on the velocity curve of an allosteric enzyme?

What would happen to [T]/[R] if substrate concentration is increased? R is the highly active form of enzyme and T is the less active form of enzyme. Assume that this is a positively cooperative enzyme, meaning that the affinity for substrate increases with increasing substrate concentration. - [T]/[R] would decrease - [T]/[R] would increase - [T]/[R] would remain the same

What is the "catalytic triad" of chymotrypsin, a type of serine protease? -the enzyme-cofactor-substrate complex -the amino acids serine, histidine, and aspartate -the amino acids serine, histidine, and glutamate -the enzyme-cofactor-intermediate complex -the amino acids cysteine, histidine, and aspartate

Which of the following amino acids have side chains that fit into the specificity pocket of chymotrypsin? Select all the amino acids that fit. You will need to check more than one amino acid. -arginine -tyrosine -phenylalanine -aspartate -glycine

Consider the hypothetical serine protease: contains a glutamic acid in the bottom. What type of amino acid would interact here?

Consider the hypothetical serine protease: contains a small, hydrophobic pocket. What type of amino acid would interact here?

Consider the hypothetical serine protease: contains a deep, hydrophobic pocket. What type of amino acid would interact here?

Which of the following is not a biopolymer? -glucose -protein -polysaccharide -nucleic acids

Which of the following subcellular components has a dimension of ~20nm? -H2O -ribosome -hemoglobin -glucose

Which statement about water is false? -water can form hydrogen bonds with other molecules -water is a solvent and dissolves polar molecules -water molecules are polar -nonpolar substances readily dissoce in water

Which of the following is not a noncovalent interaction? -disulfide bonds -hydrophobic interactions -Van der Waals forces -charge-charge interactions -hydrogen bonds

Which of the following two functional groups are common to all amino acid residues? -carboxylic acid -amine -imidazole -guanidine

Which of the following technique is not a protein purification technique? -ion-exchange chromotography -gel-filtration chromatography -mass spectrometry -affinity chromatography

Which of the following statements about proteins is false? -protein has three-dimensional structures -protein structure is a mystery and cannot be determined -alpha helix and beta strand are typically secondary structures -non-covalent interactions assist protein folding

Which of the following statements about myoglobin and hemoglobin is false? -both are oxygen binding proteins -both have a heme prosthetic group -both have the same oxygen binding curve -oxygen binds reversibly to heme

Which of the following statement is true? -Enzyme-catalyzed reactions do not need to overcome any energy barrier -The transition state is stable enough to be detected -Mechanisms of enzyme-catalyzed reactions include nucleophilic substitutions, cleavage reactions, and oxidation-reduction reactions. -pH has no effect on enzyme catalysis

Which of the following is not a serine protease? -chymotrypsin -trypsin -elastase -lysosyme

Which of the following statement is false about enzymes? -enzymes are catalyst -an enzyme catalyze a specific biological reaction -an enzyme-catalyzed reaction can be 10^3 to 10^20 times faster than the corresponding uncatalyzed reaction. -enzymes are consumed after a reaction

Inhibitors of enzymes _____. -can decrease rates of enzyme-catalyzed reactions -have no effect on kinetic constants -do not directly interact with enzymes -all of the above