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WorksheetsProteins
Total questions: 20
Worksheet time: 10mins
All proteins contain the
Same 20 amino acids
Different amino acids
300 Amino acids occurring in nature
Only a few amino acids
The optically inactive amino acid is
Glycine
Serine
Threonine
Valine
Sulphur containing amino acid is
Methionine
Leucine
Valine
Asparagine
An example of sulphur containing amino acid is
2-Amino-3-mercaptopropanoic acid
2-Amino-3-methylbutanoic acid
2-Amino-3-hydroxypropanoic acid
Amino acetic acid
All the following are sulphur containing amino acids found in proteins except
Cysteine
Cystine
Methionine
Threonine
An aromatic amino acid is
Lysine
Tyrosine
Taurine
Arginine
Amino acid with side chain containing basic groups is
2-Amino 5-guanidovaleric acid
2-Pyrrolidine carboxylic acid
2-Amino 3-mercaptopropanoic acid
2-Amino propanoic acid
An essential amino acid in man is
Aspartate
Tyrosine
Methionine
Serine
Non essential amino acids
Are not components of tissue proteins
May be synthesized in the body from essential
amino acids
Have no role in the metabolism
May be synthesized in the body in diseased
states
Which one of the following is semiessential amino acid for humans?
Valine
Arginine
Lysine
Tyrosine
The amino acid with a nonpolar side chain is
Serine
Valine
Asparagine
Threonine
Biuret reaction is specific for
–CONH-linkages
–CSNH2 group
–(NH)NH2 group
All of these
Sakaguchi’s reaction is specific for
Tyrosine
Proline
Arginine
Cysteine
Million-Nasse’s reaction is specific for the amino acid:
Tryptophan
Tyrosine
Phenylalanine
Arginine
In proteins the α-helix and β-pleated sheet are examples of
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
At the lowest energy level α-helix of polypeptide chain is stabilised
By hydrogen bonds formed between the H of
peptide N and the carbonyl O of the residue
Disulphide bonds
Non polar bonds
Ester bonds
The a-helix of proteins is
A pleated structure
Made periodic by disulphide bridges
A non-periodic structure
Stabilised by hydrogen bonds between NH
and CO groups of the main chain
Denaturation of proteins results in
Disruption of primary structure
Breakdown of peptide bonds
Destruction of hydrogen bonds
Irreversible changes in the molecule
Proteins contain
Only L- α- amino acids
Only D-amino acids
DL-Amino acids
Both (A) and (B)
At neutral pH, a mixture of amino acids in solution would be predominantly:
Dipolar ions
Nonpolar molecules
Positive and monovalent
Hydrophobic
