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Biochemistry Exam 1

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Combination of the most recent oldies questions from amino acids to Enzymes I,II lectures.
Monty2989
Quiz by Monty2989, updated more than 1 year ago
Monty2989
Created by Monty2989 about 10 years ago
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Question 1

Question
An individual molecule of glycine possesses ________ carbon(s), and an individual molecule of alanine possesses _______ carbon (s).
Answer
  • 2,2
  • 1,2
  • 2,1
  • 2,3
  • 3,2

Question 2

Question
A recent study found that polyQ aggregation can interfere with the clearance of misfiled proteins in the cytosol. PolyQ is a serial repeat of _____________ residues.
Answer
  • Arginine
  • Glycine
  • Glutamate
  • Ubiquitin
  • Glutamine

Question 3

Question
With the exception of glycine, all the standard proteinogenic amino acids __________
Answer
  • Contain an optically inactive alpha carbon
  • Do not exhibit chirality
  • Are found in biological systems in equal ratios of the two superimposable stereoisomeric conformations
  • All of the above are true
  • None of the above are true

Question 4

Question
_______________ is formed by post-translational modification of the collagen molecule.
Answer
  • Proline
  • Hydroxyproline
  • Pyrrolysine
  • Selenocysteine
  • Gamma-carboxyglutamate

Question 5

Question
Phosphates cannot normally be attached to ________________ .
Answer
  • Asparagine
  • Serine
  • Threonine
  • Phosphates cannot be attached to any of the above
  • Phosphates can be attached to all of the above

Question 6

Question
At neutral pH, the side chains of __________ are charged.
Answer
  • Lysine
  • Arginine
  • Aspartic acid
  • The side chains of all of the above are charged
  • The side chains of none of the above are charged

Question 7

Question
Which of the following bonds in a peptide exhibits the greater amount of free rotation?
Answer
  • The bond between the carbonyl carbon and the nitrogen of the peptide bond
  • The bond between the alpha carbon and the alpha-amino (the amino group attached to the central carbon of an amino acid)

Question 8

Question
A decapeptide (peptide composed of 10 amino acids) contains ______ peptide bonds. _____________ of these peptide bonds possess polarity and also partial double bond character.
Answer
  • Two, None
  • Nine, Nine
  • Ten, None
  • Eleven, Ten
  • Nine, None

Question 9

Question
A disulfide bond can be formed by the _________ of two _________
Answer
  • Reduction, selenocysteines
  • Oxidation, selenocysteines
  • Reduction, cystines
  • Oxidation, cystines
  • None of the above

Question 10

Question
Serotonin is synthesized from an amino acid precursor. This amino acid is ____________.
Answer
  • Tyrosine
  • Histidine
  • Cysteine
  • Tryptophan
  • Threonine

Question 11

Question
An alpha-helix is stabilized by __________________.
Answer
  • Hydrogen bonding between peptide-bond carbonyl oxygens and amide hydrogens
  • Disulfide bond formation between cysteine residues located 4 amino acids away from each other
  • Hydrophobic interactions between non polar side chains
  • All of the above
  • None of the above

Question 12

Question
A(n) _______________ can be formed from two or more separate polypeptide chains (or segments of polypeptide chains) arranged either in a parallel or in an anti-parallel manner relative to each other.
Answer
  • Alpha-helix
  • Beta-sheet
  • Both alpha and beta
  • Neither alpha nor beta

Question 13

Question
_________ structure can be possibly stabilized by covalent bonds, hydrophobic interactions, hydrogen bonds, or ionic interactions
Answer
  • Tertiary
  • Quaternary
  • Both T and Q
  • Neither T nor Q

Question 14

Question
A monomeric protein is denatured by exposure to a chaotropic agent. This act of denaturation can result in the unfolding and disorganization of the protein's ____________.
Answer
  • Secondary
  • Tertiary
  • Both
  • Neither

Question 15

Question
Which of the following statements about beta-amyloid is (are) true?
Answer
  • It is a highly denatured peptide that consists of many different random conformations
  • It is associated with the deposition of plaques inside certain key neurons
  • It always results from a genetically encoded amino acid substitution
  • All of the above are true
  • None of the above are true

Question 16

Question
Which of the following statements about prions is (are) true?
Answer
  • The prion genome consists of a single molecule of RNA
  • The prion genome codes for an inherently unstable peptide
  • Both statements are true
  • Neither statement is true

Question 17

Question
One is comparing the noninfectious, normal PrP in a healthy brain to the infectious PrP. The infectious PrP ___________ relative to the normal PrP
Answer
  • Exhibits less resistant to proteolytic degradation
  • Exhibits a greater tendency to form insoluble aggregates of fibrils
  • Both
  • Neither

Question 18

Question
The reaction A-B + water ---> A-OH + B-H is enzymatically mediated by a(n) ___________.
Answer
  • Isomerase
  • Ligase
  • Transferase
  • Hydrolase
  • None of the above

Question 19

Question
An enzyme binds its substrate under optimal conditions. Upon this binding, which of the following will subsequently occur?
Answer
  • An enzyme-substrate complex is produced
  • Binding of the substrate causes a conformational change in the enzyme
  • Enzyme-substrate complex is converted to an enzyme-product complex
  • All statements are true
  • None are true

Question 20

Question
An enzyme functions by ______________
Answer
  • Increasing the free energy of activation
  • Decreasing the free energy of the reactants
  • Increasing the free energy of the product
  • All statements are true
  • None of the statements are true

Question 21

Question
Which of the following statements about the tau protein is (are) true?
Answer
  • The normal version of tau helps in the assembly and stabilization of the intracellular micro tubular structure
  • The abnormal tau results from the substitution of a valine to a glutamate
  • The abnormal tau is hypophosphorylated (fewer phosphates than normal) and is highly soluble
  • All are true
  • None are true

Question 22

Question
Protein X is a large and complex polypeptide. X's secondary and tertiary structure would be potentially altered the most by the substitution of a single ______ for a single ________
Answer
  • arginine, lysine
  • alanine, valine
  • glutamate, aspartate
  • serine, proline
  • glutamine, asparagine

Question 23

Question
Which of the following statement(s) about amino acids is (are) correct?
Answer
  • Certain amino acids can function in neurotransmission
  • Certain neurotransmitters are derived from amino acids
  • Certain hormones are derived from amino acids
  • Certain amino acids are not incorporated into proteins (non-proteogenic)
  • All are correct

Question 24

Question
Which of the following statements is (are) correct?
Answer
  • Glycine is not a chiral molecule
  • Glycine can be found in both an L and D form in many human proteins
  • Glycine has an asymmetric center at the alpha carbon
  • All are correct
  • None are correct

Question 25

Question
Which of the following amino acids would be least likely to be found on the outside surface of a protein buried inside of a hydrophobic environment?
Answer
  • Tyrosine
  • Phenylalanine
  • Leucine
  • Tryptophan
  • Alanine

Question 26

Question
The formation of a disulfide bond by the oxidation of two ______ residues can contribute to the stability of proteins
Answer
  • Methionine
  • Proline
  • Cysteine
  • Histidine
  • All options

Question 27

Question
Which of the following statements about amino acids is (are) correct?
Answer
  • The side chains of certain amino acids contain a carboxylate group
  • The side chains of certain amino acids contain an amide group
  • The side chains of certain amino acids contain polar hydroxyl groups, which can serve as sites of attachment for compounds that are not amino acids
  • All are correct
  • None are correct

Question 28

Question
Which one of the following statements about protein structure is correct?
Answer
  • Proteins consisting of one polypeptide can have quaternary structure
  • The formation of a disulfide bond in a protein requires that the two participating cysteine residues by adjacent to each other in the primary sequence of the protein
  • The stability of quaternary structure in proteins is mainly a result of covalent bonds among the subunits
  • The denaturation of proteins always leads to irreversible loss of secondary and tertiary structure
  • The information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain

Question 29

Question
Which one of the following statements is correct?
Answer
  • The alpha-helix can be composed of more than one polypeptide chain
  • B-sheets exist only in the anti-parallel form
  • There are 3.6 amino acids in each turn of an alpha helix
  • Domains are a type of secondary structure
  • The alpha-helix is stabilized primarily by ionic interactions between the side chains of amino acids

Question 30

Question
Which of the following statements about the normal form of PrP is (are) correct?
Answer
  • It has a different gene sequence relative to the infectious form
  • It has a different amino acid sequence relative to the infectious form
  • It has fewer B-sheets and more A-helices than the infectious form
  • It is more resistant to proteolytic degradation than the infectious form
  • It plays a significant role in the development of Alzheimer disease

Question 31

Question
A peptide bond:
Answer
  • Has partial double bond character
  • Is ionized at physiological pH
  • Is cleaved by agents that denature proteins, such as organic solvents and high concentrations of urea
  • Is stable to heating in strong acids
  • Most commonly in the cis configuration

Question 32

Question
Which of the following statements about the alpha-helix is (are) correct?
Answer
  • The sequence of amino acids in the alpha-helix always shows a predictable pattern of specific amino acids throughout the length of the entire helix
  • The formation of the alpha-helix is always mediated by the enzymatic activity of enzymes known as alpha-helicases
  • Approx. 50% of the alpha-helices are found in a parallel configuration, while about 50% are in anti-parallel configuration
  • All are correct
  • None are correct

Question 33

Question
Which of the following interactions can cooperate in the stabilization of the tertiary structure:
Answer
  • Ionic interactions between negatively charged and positively charged side chains
  • Hydrophobic interactions between different non polar side chains
  • Disulfide covalent linkages between two noncontiguous cysteine residues
  • All cooperate
  • None of the options cooperate

Question 34

Question
Which of the following statements about the neurofibrillary tangles associated with Alzheimer disease is (are) correct?
Answer
  • The neurofibrillary tangles are extra-cellular aggregates that tend to accumulate both in the brain and other regions of the central nervous system
  • There is significant evidence that these neurofibrillary tangles are usually caused by the ingestion of a pathogenic protein known as tau
  • The neurofibrillary tangles are generally intertwined with the intra-cellular amyloid plaque
  • All are correct
  • None are correct

Question 35

Question
Which of the following is the least likely to be disrupted by denaturation of a protein?
Answer
  • Disulfide bonds
  • Hydrophobic interactions
  • Peptide bonds
  • Weak noncovalent interactions
  • Hydrogen bonds

Question 36

Question
The addition of a hydroxyl to __________ produces tyrosine
Answer
  • Valine
  • Tyrosine
  • Phenylalanine
  • Glycine
  • Proline

Question 37

Question
This is an optically inactive amino acid
Answer
  • Valine
  • Tyrosine
  • Phenylalanine
  • Glycine
  • Proline

Question 38

Question
This is the precursor of dopamine, epinephrine, and norepinephrine
Answer
  • Valine
  • Tyrosine
  • Phenylalanine
  • Glycine
  • Proline

Question 39

Question
An example of an imino acid
Answer
  • Valine
  • Tyrosine
  • Phenylalanine
  • Glycine
  • Proline

Question 40

Question
Branched chain amino acid
Answer
  • valine
  • tyrosine
  • phenylalanine
  • glycine
  • proline

Question 41

Question
Protein P is a protein found inside a lipid environment. Which of the following amino acids would be most likely to be found on the outside surface of P
Answer
  • Aspartic acid
  • lysine
  • isoleucine
  • asparagine
  • arginine

Question 42

Question
Drug D has one ionizable group, an amino group, with a pKa of 9.0. This drug can pass through cell membranes most readily when uncharged. Theoretically, passage of the drug would occur most readily at pH ___________.
Answer
  • 2.5
  • 4.5
  • 6.5
  • 7.5
  • 9.3

Question 43

Question
Which of the following amino acids participates the most in protein buffering of blood?
Answer
  • histidine
  • proline
  • alanine
  • tryptophan
  • phenylalanine

Question 44

Question
PrP(Sc) is the causative agent of transmissible spongiform encephalopathies because of:
Answer
  • A single point mutation in the gene coding for the PrP(Sc)
  • The ability of the PrP(Sc) to complex with an infectious molecule of nucleic acid
  • A higher proportion of alpha-helical structures in the PrP(Sc)
  • All are correct
  • None are correct
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