Question 1

Which of the following statements best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids linked by peptide bonds.

Question 2

A protein has a molecular weight of 55,000 Da. Approximately how many amino acid residues does it contain? Use the average residue weight of 110 Da.

Accepted Answer

$$\frac{55,000}{110} = 500$$ residues

Question 3

Which protein type is primarily responsible for catalyzing biochemical reactions in living cells?

Accepted Answer

Enzymes

Question 4

Which purification technique would be most suitable for separating proteins based on their size and shape?

Accepted Answer

Gel filtration chromatography

Question 5

Antibodies are an example of which type of protein, and what is their primary biological function?

Accepted Answer

Defence proteins; bind antigens to neutralize pathogens

Question 6

Which of the following is a conjugated protein, and what distinguishes it from a simple protein?

Accepted Answer

Haemoglobin; contains a prosthetic group

Question 7

A researcher wants to purify a protein that is highly hydrophobic. Which chromatography method should they use?

Accepted Answer

Hydrophobic interaction chromatography

Question 8

Which of the following is NOT a typical industrial application of proteases?

Accepted Answer

Blood glucose monitoring

Question 9

Which statement about multi-subunit proteins is correct?

Accepted Answer

Subunits can be identical or different, as in haemoglobin.

Question 10

Why is it important to use a buffer during protein purification?

Accepted Answer

To maintain the pH and preserve protein biological activity.

Question 11

Which protein is used as a therapeutic agent to treat diabetes?

Accepted Answer

Insulin

Question 12

A protein sample is found to lose its biological activity outside a narrow pH range. What is the most likely explanation?

Accepted Answer

Protein denaturation due to pH-induced changes in structure.

Question 13

Which of the following proteins is an example of a metalloprotein?

Accepted Answer

Haemoglobin

Question 14

Which step is typically performed first when isolating a protein from cells?

Accepted Answer

Cell lysis to release intracellular proteins

Question 15

Which protein is involved in muscle contraction?

Accepted Answer

Actin

Question 16

A protein is found to have a prosthetic group derived from a vitamin. What type of protein is this?

Accepted Answer

Conjugated protein

Question 17

Which of the following is a correct match between protein type and function?

Accepted Answer

Regulatory protein – insulin

Question 18

Which protein purification method would be most effective for separating proteins based on their charge?

Accepted Answer

Ion exchange chromatography

Question 19

A patient is treated with tissue plasminogen activator (tPA) after a heart attack. What is the role of tPA?

Accepted Answer

It acts as a thrombolytic agent to dissolve blood clots.

Question 20

Which of the following statements about protein structure is correct?

Accepted Answer

Some proteins consist of multiple polypeptide chains, which may be identical or different.

Topic 5 – Proteins: Structure, Function, and Purification

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