Amino Acids And Proteins Chemistry Solved Question

Question/Answers

Q. The linkage that stabilized the tertiary structure of the protein?

Ans. Hydrophobic Interaction

Q. The method used to study the tertiary structure of the protein.

Ans. X-ray Crystallography

Q. DNA concentration is measured by?

Ans. Spectrophotometry

Q. How does Histidine E7 provide a hindered environment?

Ans.

• Carbon monoxide has 2 atoms: C and O.
• Fe2+ is present below the plane of the ring.
• C binds opposite to Fe2+ perpendicular to the ring.
• O tries to bind to C but Histidine E7 doesn't allow this binding → Hindering the environment.

Also read: Genetics Questions Solved for NEET PG Biochemistry Preparation

Q. Does Histidine E7 act the same way when oxygen binds?

Ans.

• Oxygen also has 2 atoms: O and O.
• First O binds perpendicular to the plane of the ring.
• Second O binds in an inclined position.
• Not hindered by Histidine E7

Q. Name the preferred sample for electrophoresis between serum and plasma samples.

Ans. Serum is preferred due to absence of fibrinogen. (Fibrinogen present in plasma forms a band in the gamma region that can obscure multiple myeloma bands.)

Q. A protein was run through SDS-PAGE and gave rise to a band corresponding to 100 kDa. After the protein was treated with mercaptoethanol, it gave rise to two bands: one corresponding to 20 kDa and the other corresponding to 30 kDa. What is your comment on the protein? Whether it is a monomer, dimer, or tetramer?

Ans. A monomer when treated with mercaptoethanol forms the same band in the 100 kDa region. Here, it's distributed between two bands, which means it is not a monomer. The substance in question cannot be a dimer because its molecular weight corresponds to 20 and 30 kDa; for dimer, the entire molecular weight should be equal to 100 kg Dalton. Therefore, the protein is a tetramer with two subunits of molecular weight 30 kDa and two subunits of molecular weight 20 kDa; when added together, they become 100 kg Dalton (total molecular weight of the protein).

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Q. Which is the fastest moving amino acid in paper chromatography?

Ans. In paper chromatography, amino acid which has maximum polarity moves fastest.

Q. What is the most common technique for HbA1c estimation?

Ans. Cation exchange chromatography is the most common technique for HbA1c estimation.

Important MCQs

Q. Ninhydrin test gives purple color with all except:

1. Glycine
2. Alanine
3. Glutamine
4. Proline

Q. Biuret test gives violet color with all except:

1. Albumin
2. Glycoproteins
3. Glutathione
4. Dipeptide

Also read: Biochemistry Important Questions For NEET PG/FMG Exams

Q. The xanthoproteic acid test is answered by:

1. Histidine
2. Arginine
3. Cysteine
4. Tyrosine

Q. Which of the following is optically inactive?

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

Q. All of the following have hydroxyl groups except:

1. Cysteine
2. Tyrosine
3. Serine
4. Threonine

Q. All of the following are aromatic amino acids except.:

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

Also read: INI-CET High Yield Questions For Biochemistry

Q. All of the following are basic amino acids except?

1. Lysine
2. Glutamate
3. Arginine
4. Histidine

Q. Which of the following is an imino acid?

1. Lysine
2. Glutamate
3. Arginine
4. Proline

Q. Which of the following is a polar but uncharged amino acid?

1. Serine
2. Glutamate
3. Arginine
4. Tryptophan

Q. All the following are true about Glutathione except.

1. It is a tripeptide.
2. It has 3 peptide linkages.
3. It has a pseudo peptide linkage.
4. It is an antioxidant.

Also read: Mucopolysaccharides : Exceptions, Important Facts

Q. The primary structure of a protein is stabilized by:

1. Peptide linkage
2. Hydrogen bond
3. Hydrophobic interaction
4. Disulphide bridges

Q. The secondary structure of a protein is studied by:

1. Sanger's method
2. Optical Rotatory dispersion
3. X-ray crystallography
4. NMR Spectroscopy

Q. All the following are true about alpha helix except:

1. It is stabilized by intra-chain hydrogen bonds.
2. It is compact.
3. Proline disrupts alpha helix.
4. Left-handed helices are common.

Q. All the following are true about beta pleated sheets except:

1. It is stabilized by interchain hydrogen bonds.
2. It is extended.
3. Parallel beta pleated sheets are found.
4. Antiparallel beta pleated sheets are never possible.

Q. Which of the following is true about super secondary structures?

1. They connect adjacent tertiary structures.
2. They are found adjacent to motifs.
3. Proline is found more among these structures.
4. They are stabilized by covalent interactions.

Also read: Glycogen Storage Diseases

Q. The tertiary structure of a protein is studied by:

1. Sanger's method
2. Optical Rotatory dispersion
3. X-Ray crystallography
4. NMR Spectroscopy

Q. Globular proteins true is:

1. Structural proteins
2. The axial ratio is more than 10.
3. Compact
4. More b pleated sheets

Q. A person presented with recurrent renal stones, which were hexagonal on microscopy. He was diagnosed with cystinuria. True about Cystine is:

1. It is an amino acid.
2. It is a dipeptide.
3. It has a free sulfhydryl group.
4. It is an imino acid.

Q. The amino of globin chain that provides hindered environment for carbon monoxide binding to haemoglobin is

1. His F8
2. His E7
3. HIS H21
4. Ser H11

Q. All of the following is true about Bohr Effect except

1. Deoxygenation increases the affinity of Hemoglobin for hydrogen ions
2. Decrease in the affinity of hemoglobin for Oxygen on H+ binding
3. Happens in the lung side
4. Acidosis shifts the curve to right

Also read: Fanconi Anemia: Symptoms, Causes and Treatment

Q. Binding of carbon dioxide to haemoglobin causes which of the following?

1. Taut structure to relaxed structure
2. Relaxed structure to Taut structure
3. Both
4. None

Q. All of the following cause shift of oxyhemoglobin dissociation curve to right except

1. Alkalosis
2. 2,3-BPF
3. Hypoxia
4. Anaemia

Q. All of the following cause shift of oxyhemoglobin dissociation curve to right except

1. Increase in body temperature
2. 2,3-BPF
3. Alkalosis
4. Acclimatization

Q. Foetal haemoglobin shows higher affinity for oxygen because.

1. It exhibits higher affinity for 2,3-BPG
2. It has a lower affinity for carbon monoxide.
3. It has lower affinity for 2,3-BPG
4. It exists in a taut structure.

Also read: Phenylketonuria: Symptoms, Causes and Treatment

Q. Total number of 2,3-BPF bound to one molecule of haemoglobin during conditions of hypoxia.

1. 1
2. 2
3. 3
4. 4

Important Points to remember

• Amino acid which acts as a physiological buffer: Histidine.
• Aromatic amino acids: Phenylalanine, Tyrosine & Tryptophan.
• Optically inactive amino acid: Glycine.
• Tryptophan: aldehyde test.
• Arginine: Sakaguchi test.
• Tyrosine: Millon's test.
• Fe2+ is attached to His F8 of heme.
• The amino acid, which is responsible for the hindered environment, protecting from carbon monoxide poisoning is His E7.
• Carbon monoxide causes anaemic hypoxia.
• 2,3-BPF facilitates Taut structure of haemoglobin.
• Anaemia dissociates the oxyhaemoglobin curve to the right.
• The preferred sample for protein electrophoresis is serum.
• SDS PAGE separates protein based on molecular weight.
• The method used to study quaternary structure of protein is reducing the type of SDS page. (Where mercaptoethanol is used)
• The buffer used for elution in cation exchange chromatography is alkaline.
• The buffer used for elution in anion exchange chromatography is acidic.
• The most commonly used method for HbA1C estimation is cation exchange chromatography.

Also read: MCAD Deficiency: Causes, Symptoms, Risk Factors, Diagnosis, Treatment

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