Download Biochemistry Exam 1 (Multiple Choice + Formulas) rated A and more Exams Biochemistry in PDF only on Docsity!
Formulas) rated A
Approximately what percentage of the human genome encodes for protein? - correct answer ✅3% What pairs of atoms in bases are involved in hydrogen bonds? A) N-H and O-H B) N-H and S-H C) O-H and P-O D) All of the above E) None of the above - correct answer ✅A) N-H and O-H The structure of DNA described by Watson and Crick included A) a double helix B) the sugar phosphate backbone aligned in the center of the helix C) the base pairs that are stacked on the inside of the double helix D) A and B E) A and C - correct answer ✅E) A and C What two properties of water are important for biological interactions? - correct answer ✅The polarity of water The cohesive properties of water How many hydrogen bonds are formed between A and T? - correct answer ✅ 2
Formulas) rated A
What gives proteins a dominant role in biochemistry? - correct answer ✅Their ability to spontaneously fold into complex three-dimensional structures Which of the following is considered a noncovalent bond? A) Electrostatic interactions B) Hydrogen bonds C) Van der Waals interactions D) All of the above E) None of the above - correct answer ✅D) All of the above The First Law of Thermodynamics states what? - correct answer ✅The total energy of a system and its surroundings is constant The Second Law of Thermodynamics states what? - correct answer ✅The total entropy of a system and its surroundings always increases for a spontaneous process List atoms commonly found in biological molecules that are often hydrogen-bond acceptors. - correct answer ✅Oxygen Nitrogen What is the [A-]/[HA] ratio when the weak acid is in a solution one pH unit below its pKa? - correct answer ✅1:
Formulas) rated A
What determines a protein's function? - correct answer ✅Structure What is the name of the plot that allows one to investigate the likely orientation of certain amino acid pairs? - correct answer ✅Ramachandran What type of structure includes alpha-helices, beta-sheets, and turns? - correct answer ✅Secondary structure What type of protein structure develops when two proteins combine to form one larger protein? - correct answer ✅Quaternary structure What is responsible for the tertiary structure of proteins? - correct answer ✅Interactions between amino acid side chains Which of these agents can denature proteins? A) Salt B) Alcohol C) UV light D) All of the above - correct answer ✅D) All of the above Combining three amino acids produces what? - correct answer ✅A tripeptide + 2 water molecules
Formulas) rated A
Disulfide bonds in proteins can be reduced to free sulfhydryl groups by reagents such as _______. - correct answer ✅Beta-mercaptoethanol What type of purification is based on the attraction of the protein for a particular chemical group? - correct answer ✅Affinity chromatography What affects the sedimentation of a particle? - correct answer ✅Mass Shape Density of the solution Proteins can be separated from small molecules and ions through a semi- permeable membrane by what process? - correct answer ✅Dialysis In the Edman procedure for peptide sequence, what is used to selectively remove the N-terminal residue as a PTH-derivative. - correct answer ✅Phenyl isothiocyanate The first step in protein purification from a homogenate is usually what? - correct answer ✅Isolation by centrifugation Exclusion gel or gel-filtration chromatography separates molecules on what basis?
- correct answer ✅Size Polypeptides can be fragmented into smaller peptides by cleavage with chymotrypsin, which hydrolyzes the peptide bond at the C-terminal side of what amino acid residues? - correct answer ✅Phenylalanine
Formulas) rated A
Each amino acid residue in a protein is encoded by a set of three bases of mRNA referred to as a ______. - correct answer ✅Codon The enzyme that is capable of synthesizing DNA from an RNA template is _________. - correct answer ✅Reverse transcriptase DNA polymerase reads the template strand in what direction? - correct answer ✅3' to 5' What is the nucleotide sequence on the DNA template strand that yields the CUA codon for leucine? - correct answer ✅TAG How does a nucleotide differ from a nucleoside? - correct answer ✅A nucleotide is a nucleoside with a phosphate ester linked to the sugar The flow of genetic information from DNA to protein is called what? - correct answer ✅Gene expression A three-base codon defines a specific ______. - correct answer ✅Amino acid In DNA and RNA synthesis, the new strand growth is always in what direction? - correct answer ✅5' to 3' The difference in RNA bases compared to DNA bases is what? - correct answer ✅RNA contains U instead of T
Formulas) rated A
The nucleoside that is composed of a D-ribose linked to a cytosine base is called ______. - correct answer ✅Cytidine What was the technique used by Franklin and Wilkins to deduce the structure of DNA? - correct answer ✅X-ray diffraction The feature(s) of DNA deduced by Watson and Crick included what? A) Two antiparallel polynucleotide chains coiled in a helix around a common axis B) The pyrimidine and purine bases lie on the inside of the helix C) The bases are nearly perpendicular to the axis D) All of the above E) None of the above - correct answer ✅D) All of the above DNA renaturation after melting is called what? - correct answer ✅Annealing What is the Henderson-Hasselbach equation? - correct answer ✅pH = pKa + log [A-]/[HA] What is the equation for determining Ka? - correct answer ✅Ka = [H+][A-]/[HA] Ka = products/reactants For the reaction A + B -> 2C, give the equation for Q and Keq. Tell the difference. - correct answer ✅Q = [C]^2 / [A][B]
