exam 1 Flashcards
(13 cards)
The equilibrium constant or Keq provides information about which of the following?
A. how quickly a strong acid will completely dissociate in an aqueous solution.
B. The degree of dissociation of water when mixed with a weak acid nucleic acids.
C. The affinity of a weak acid for its proton.
D. The Ph of a solution.
E. All of the above
C. the affinity of a weak acid for its proton.
Chemical equilibrium is the state in which the reactants and products have no net change over time. This is whne the forward and reverse reactions occur at equal rate, this state of equilibrium can be described by the equilibrium constant , K
The lower the pKa of a weak acid:
A. The higher the pH of the solution
B. the less likely it is to donate a proton in aqueous solutions
C. The more likely it is to dissociate in an aqueous solution
D. The more conjugate acid would be present at a high pH.
E. All of the above could be added and be accurate
C. The more likely it is to dissociate in an aqueous solution.
The smaller the pKa value the stronger the acid.
pHpKa = fewer protons, more conjugate base (cant donate protons)
The pH optimum of enzyme “lobozyme” is 5.2. There are two acidic residues at the active site of lysozyme (E35 and D52) that are required for enzyme activity. The pKa of E35 is 5.9, whereas the pKa of D52 is 4.5. What are the primary ionization states of these two residues at the pH optimum of the enzyme?
A. E35 is protonated; D52 is ionized B. E35 is protonated; D52 is protonated C. E35 is ionized; D52 is protonated D. E25 is ionized; D52 is ionized E. This cannot be determined from the onformation provided
C. E35 is ionized; D52 is protonated
pHpKa = fewer protons, more conjugate base (cant donate protons)
To find pH= pKa+log[A-]/[HA]
Which of the following contributes most significantly to the folding of a protein in its final, most energetically stable form?
A. Hydrophobic interactions B. Ionic bonds C. Hydrogen bonds D. Van Der Wals forces E. COvalent bonds
A. Hydrophobic interactions
If a mutation in glucokinase caused a proline to be substituted for a leucine on a surface helix far from the active site, but within the hinge region of the actin fold, which one of the following would be expected?
A. there would be no effect of the rate of the reaction because the mutation is not in the active site.
B. There would be no effect on the rate of the reaction because proline and leucine are both nonpolar amino acids
C. There would be no effect on the number of substrate molecules reaching the transition state.
D. There would probably be an effect on the binding of ATP or a subsequent step in the reaction sequence
E. the reaction would probably proceed through an alternate mechanism.
D. There would probably be an effect on the binding of ATP or a subsequent step in the reaction sequence
Which of the following would be considered a “mechanism-based inhibitor”?
A. an inhibitor which binds to an allosteric site to redue activity.
B. An inhibitor which competes with another enzyme for substrate binding
C. An inhibitor which bind irreversible with function groups in the active site
D. An inhibitor which binds irreversible to the product
E. All of the above
C. An inhibitor which binds irreversibly with functional groups in the active site.
mechanism inhibitor binds to the transition state, halts reaction, requires a mechanism of enzyme to be functioning
The purine (with four nitrogen atoms) and pyrimidine (with two nitrogen atoms) bases, which are nitrogen-containing ring structures, are essential components of which biochemical macromolecule?
A. carbohydrates B. lipids C. Nucleic acids D. Proteins E. none of the above
C. Nucleic acids
Which of the following subcellular organelles has a biomembrane containing cytochrome p-450 proteins that can be involved in drug metabolism?
A. Plasma membrane B. Nuclear membrane C. Lysosomal membrane D. Golgi complex E. Smooth endoplasmic reticulum (SER)
E. Smooth endoplasmic reticulum (SER)
P450 helps to process and excrete waste found on the smooth endoplasmic reticulum
Allosteric inhibitor
binds away from the active site to effect enzyme
Competitive inhibitor
binds to the active site of an enzyme
What does it mean if a compound is saturated? unsaturated?
saturated= no double bonds unsaturated= has double bonds
Bacteria contain a cell wall and a plasma membrane. antibiotics targeting the cell wall do not effect human cells because the human cells to not express a cell wall. however, antibiotics cannot target plasma membranes because both bacteria and humans express such membranes. Which on of the following is a characteristic of the eukaryotic plasma membrane?
A. it contains oligosacharides sandwhiched between the inner and outer leaflets.
B. It contains more phosphatidylserine in the inner than the outer leaflet.
C. It contains phospholipids with their acyl groups extending into the cytosol.
D. It contains principally nonpolar lipids
E. It is composed principally of triacylglycerols and cholesterol
D. It contains principally nonpolar lipids
What is the most common phospholipid present in most cellular plasma membranes?
A. phosphatidylcholine B. phophatidylethanolaine C. phosphatidylserine D. phosphatidylinositol E. sphinomyelin
D. Phosphatidylinositol
