BIO213: Chemistry Of Amino Acids And Proteins TMA3 Question and Answer

BIO213: Chemistry Of Amino Acids And Proteins TMA3

Question 1 : Which of these uncommon amino acids is a precursor of arginine
A. Ornithine
B. Penicillamine
C. Serotonin
D. Citrulline

Answer to question 1 is D. Citrulline

Question 2 : One of these staements is not true of peptides
A. They are Ionic
B. The precise number of water molecule lost during formation is one less than the number of amino acid residues in a peptide
C. The have two terminals
D. In a peptide, amino acid residue is linked to its neighbour in a tail-to head manner

Answer to question 2 is A. They are Ionic

Question 3 : When amino acids react with Ninhydrin all but one of these substances is formed.
A. Aldehyde
B. Water
C. Ammonia
D. Carbondioxide

Answer to question 3 is B. water

Question 4 : Polymers composed of few (3-10) amino acids residues are known
A. Oligopeptides
B. Polypeptides
C. Proteins
D. Peptidechains

Answer to question 4 is A. Oligopeptides

Question 5 : What is the function of the gel used in gel filtration?
A. Acts as molecular sieve
B. Acts as magnet
C. Acts as gum
D. Acts as adsorbent

Answer to question 5 is A. Acts as molecular sieve

Question 6 : Which of these amino acids forms a red precipitate with bromine water?
A. Tyrosine
B. Tryptophan
C. Arginine
D. Serine

Answer to question 6 is C. Arginine
Question 7 : An example of an uncommon amino acid that acts as a hormone.
A. Serotonin
A. Valine
B. Glycine
C. Epinephrine

Answer to question 7 is C. Epinephrine

Question 8 : Alanine has only one chiral center, how many stereoisomers does it have?
A. 1
B. 2
C. 0
D. 4

Answer to question 8 is B. 2

Question 9 : The following are examples of gel materials except ______________________
A. Polyacrylamide
B. Dextran
C. Sepharose
D. Amylose

Answer to question 9 is D. Amylose

Question 10 : One of these amino acids will not give a purple colour with Ninhydrin
A. Lysine
B. Leucine
C. Proline
D. Arginine

Answer to question 10 is C. Proline

Question 11 : Which of these statements is not true of a buffer system
A. It can resist a change in pH
B. If acid is added, the conjugate base interacts with it to produce the weak acid and so resist the change in the pH
C. If base is added, the weak acid interacts with it to give water and conjugate base
D. the buffer system is irreversible

Answer to question 11 is D. the buffer system is irreversible

Question 12 : Mention the amino acid that yields a yellow colour when it reacts with Ninhydrin.
A. Proline
B. Serine
C. Tyrosine
D. Phenyl alanine

Answer to question 12 is A. Proline

Question 13 : In a peptide chain residues are numbered from____
A. Least amino acid
B. The Largest amino acid
C. The C- terminal
D. The N-terminal

Answer to question 13 is D. The N-terminal

Question 14 : Calculate the pKa of lactic acid given that at pH 4.8, the concentration of lactic acid and its conjugate base is 0.001 and 0.087 M respectively.
A. 7.4
B. 2.86
C. 2.74
D. 3.68

Answer to question 14 is B. 2.86

Question 15 : An example of an amino acid whose side chain is an aliphatic chain terminating in an acidic carboxyl is_______
A. Aspartate
B. Serine
C. Glutamine
D. Asparagine

Answer to question 15 is A. Aspartate

Question 16 : Amino acid polymers with molecular weight less than 10,000 are called _____________.
A. Proteins
B. Peptides
C. Nucleic acids
D. Sugars

Answer to question 16 is B. Peptides
Question 17 : What is the term for stereoisomers that are mirror images of each other?
A. Enantiomers
B. Diastereoisomers
C. Stereoisomers
D. Chiral

Answer to question 17 is A. Enantiomers

Question 18 : One of these groups plays an important role in Sakaguchi reaction
A. imidazole group
B. Imino group
C. guanidinium group
D. amide group

Answer to question 18 is C. guanidinium group

Question 19 : Which of these is not a peptide found in living systems?
A. Proline
B. Glutathione
C. Oxytocin
D. Vasopresin

Answer to question 19 is A. Proline

Question 20 : The α-carboxyl group can react with ammonia to yeild one of the following
A. Amide
B. Ester
C. Alkanol
D. Aldehyde

Answer to question A. Amide