Olete.in – MCQs, Mock Tests & Government Job Prep | Biochemistry Biochemistry -Structure and Properties of Amino Acids

When the amino acid alanine (R-group is CH3) is added to a solution with a pH of 7.3, alanine becomes

1. an isotope
2. a cation
3. nonpolar
4. a zwitterions

✅ Correct Answer: 4

What is the end product of leucine metabolism?

1. Acetyl-CoA
2. Pyruvic acid
3. Oxaloacetic acid
4. Acetyl carnitine

✅ Correct Answer: 1

What is the heaviest of the twenty amino acids?

1. Phenylalanine
2. Tryptophan
3. Tyrosine
4. Histidine

✅ Correct Answer: 2

Which of the following amino acids can form hydrogen bonds with their side (R) groups?

1. Asparagine
2. Aspartic acid
3. Glutamine
4. All of these

✅ Correct Answer: 4

The isoelectric point of an amino acid is defined as the pH

1. where the molecule carries no electric charge
2. where the carboxyl group is uncharged
3. where the amino group is uncharged
4. of maximum electrolytic mobility

✅ Correct Answer: 1

Molecules that bear charged groups of opposite polarity are known as

1. zwitterions
2. ambions
3. ion conversion
4. amphions

✅ Correct Answer: 1

What is the product of the catabolic breakdown of Arginine?

1. Alpha-ketoglutarate
2. Fumarate
3. Oxaloacetate
4. Succinate

✅ Correct Answer: 1

Which amino acids would most likely reside in the membrane-anchoring domain of a membrane embedded protein?

1. Isoleucine, valine and phenylalanine
2. Phenylalanine, valine, and aspartate
3. Leucine, threonine, and lysine
4. Lysine, arginine and histidine

✅ Correct Answer: 1

An essential amino acid is one that

1. is essentially easy to synthesize
2. is essential to flagella motion
3. the body cannot synthesize
4. the body can synthesize under essential conditions

✅ Correct Answer: 3

D-Alanine and L-Alanine are technically known as

1. anomers
2. enantiomers
3. epimers
4. polymer

✅ Correct Answer: 2

Which of the following pairs of amino acids would carry a negative charge on their side chain at pH 8.0?

1. Asparagine & Glutamine
2. Leucine & Glycine
3. Histidine & Lysine
4. Aspartate & Glutamate

✅ Correct Answer: 4

In a polypeptide average mass of an amino acid residue is

1. 110 daltons
2. 118 daltons
3. 80 daltons
4. 150 daltons

✅ Correct Answer: 1

Which pair of amino acids absorbs the most UV light at 280 nm?

1. Threonine & Histidine
2. Trp & Tyrosine
3. Cystein & Asparagine
4. Phenylalnine & Proline

✅ Correct Answer: 2

Which of the following is a nonstandard amino acid?

1. Cysteine
2. Isoleucine
3. Hydroxyproline
4. Histidine

✅ Correct Answer: 3

Which of the following is an essential amino acid?

1. Tryptophan
2. Methionine
3. Lysine
4. All of these

✅ Correct Answer: 4

Protein fluorescence arises primarily from which residue?

1. Arginine
2. Tryptophan
3. Tyrosine
4. Phenylalanine

✅ Correct Answer: 2

Which of the following amino acid is known as half-cystine residue?

1. Cysteine
2. Isoleucine
3. Valine
4. Histidine

✅ Correct Answer: 1

Which of the following is not an essential amino acid?

1. Aspartic acid
2. Glutamic acid
3. Glycine
4. All of these

✅ Correct Answer: 4

Which of the following is not a sensible grouping of amino acids based on their polarity properties?

1. Ala, Leu, and Val
2. Arg, His, and Lys
3. Phe, Trp, and Tyr
4. Asp, Ile, and Pro

✅ Correct Answer: 4

Proteins and macromolecular structures take on their higher order structures

1. by self-assembly
2. with the help of molecular chaperons
3. with the help of precursor sequences that are removed from the final structures
4. all of the above

✅ Correct Answer: 4

What is the product of the catabolic breakdown of Alanine?

1. Fumarate
2. Oxaloacetate
3. Pyruvate
4. Malate

✅ Correct Answer: 3

How many different amino acids are there?

1. 3
2. 20
3. 100
4. An infinite number

✅ Correct Answer: 2

Amino acids required in the human diet and not synthesized by the body are called

1. specialized
2. trace
3. essential
4. accessory

✅ Correct Answer: 3

Which of the following amino acid contain an imidazolium moiety?

1. Alanine
2. Valine
3. Cysteine
4. Histidine

✅ Correct Answer: 4

The sequence of letters 'WYQN' will represent

1. Tryptophan, tyrosine, glutamic acid, asparagine
2. Tryptophan, tyrosine, glutamine, asparagine
3. Tryptophan, glutamine, tryptophan, asparagine
4. Glutamine, tyrosine, tryptophan, aspartic acid

✅ Correct Answer: 2

The sulphur containing side chain of cysteine is

1. ampiphillic, highly reactive and capable of reacting with another cysteine
2. hydrophillc, highly reactive and capable of reacting with another cysteine
3. hydrophobic, highly reactive and capable of reacting with another cysteine
4. none of the above

✅ Correct Answer: 3

Which of the following is a nonprotein amino acid?

1. Dopamine
2. Hydroxylysine
3. Cystine
4. none of the these

✅ Correct Answer: 1

Serine and threonine are polar amino acids due to

1. reactive hydroxyl group in the side chain
2. reactive alcoholic group in the side chain
3. reactive keto group in the side chain
4. reactive aldehyde group in the side chain

✅ Correct Answer: 1

Which of the following is not the hydrophobic and aromatic amino acid?

1. Phenylalanine
2. Tyrosine
3. Tryptophan
4. none of the these

✅ Correct Answer: 4

Stereo chemical configuration of all a-amino acids derived from proteins is

1. L
2. D
3. L and D
4. None of these

✅ Correct Answer: 1

The α-amino acids have a carboxyl group with a pK around __________ , and an amino group with a pK near __________ .

1. 1.1, and 12.1
2. 6.5, and 8.0
3. 3.3, and 10.5
4. 2.2, and 9.4

✅ Correct Answer: 4

Coomassie Blue stains the proteins by reacting with

1. arginine residues
2. free c-termini
3. peptide bonds
4. aromatic ring

✅ Correct Answer: 1

Which amino acid when exposed to ninhydrin produces a brown color?

1. Asparagine
2. Proline
3. Alanine
4. Valine

✅ Correct Answer: 1