Best MCQs of Protein all important exam Success keys -

MULTIPLE CHOICE QUESTIONS MCQs ON PROTEIN CHEMISTRY

1. Proteins are high molecular weight polymers of a group of low molecular weight monomers called:

A) Lipids

B) Carbohydrates

C) Amino acids

D) Nucleoproteins

Q2. What is intimately associated with cell division and heredity, found in the cell nucleus?

A) Enzymes

B) Amino acids

C) Lipids

D) Nucleoproteins

Q3.Enzymes primarily serve what function in the cell cytoplasm?

A) Provide structure

B) Catalyze chemical changes

C) Store energy

D) Transport oxygen

Q4.Excess proteins in animals can serve as a source of:

A) Connective tissue

B) Simple diffusible nutrients

C) Energy and fat

D) Hormones

Q5.The most abundant substances in cell protoplasm are:

A) Carbohydrates

B) Lipids

C) Amino acids

D) Proteins

Q6.How many amino acids have been isolated from the proteins of all major classes of living organisms, common to all?

A) More than 80

B) 9

C) 18

D) 20

Q7. Amino acids that cannot be synthesized from other substances by the body cells are called:

A) Nonessential amino acids

B) Non-nitrogenous amino acids

C) Essential amino acids

D) Alpha amino acids

Q8.Which of the following is listed as an essential amino acid?

A) Glycine

B) Alanine

C) Phenylalanine

D) Proline

Q9.Which of the following is listed as a nonessential amino acid?

A) Methionine

B) Tryptophan

C) Histidine

D) Glycine

Q10.In the general formula for a protein chain, what does ‘R’ represent?

A) The peptide linkage

B) The free terminal amino group

C) The distinctive aromatic or aliphatic radical of any of the 18 amino acids

D) The carboxyl group

11.Amino acids with side chains containing basic groups include:

A) Serine, Threonine

B) Aspartic acid, Glutamic acid

C) Arginine, Lysine, Histidine

D) Glycine, Alanine

12.The number of amino acids absorbed from the intestine into the portal blood following digestion of a normal diet is approximately:

A) 18

B) 10

C) 20

D) 51

13.Long chains of amino acids linked by the peptide bond are called:

A) Monopeptides

B) Dipeptides

C) Polypeptides

D) Simple globular proteins

14.The simplest combination of amino acids that contains a peptide linkage is called a:

A) Polypeptide

B) Tripeptide

C) Dipeptide

D) Tetrapeptide

15.What is the number and order of amino acids in the polypeptide chains referred to as?

A) Secondary structure

B) Quaternary structure

C) Tertiary structure

D) Primary structure

16.The folding of polypeptide chains into a specific coiled structure held together by disulfide and hydrogen bonds is the definition of which protein structure?

A) Primary structure

B) Secondary structure

C) Tertiary structure

D) Quaternary structure

17.What are the three forms in which the polypeptide backbone exists in different sections of a protein?

A) Fibrous protein, Globular protein, Conjugated protein

B) alpha-helix, \beta-pleated sheet, Random coil

C) Monomeric, Dimeric, Tetrameric

D) Primary, Secondary, Tertiary

18.The arrangement and interrelationship of the twisted chains of protein into specific layers, crystals or fibers is called the:

A) Primary structure

B) Secondary structure

C) Tertiary structure

D) Quaternary structure

19.Quaternary structure is displayed when several monomeric units combine, where these subunits are held together primarily by:

A) Peptide bonds

B) Strong covalent bonds

C) Non-covalent bonds such as hydrogen and ionic bonds

D) Ether linkages

20.In the structure of collagen, what residue is found nearly every third position because it is the only amino acid that can fit into the triple stranded helix?

A) Proline

B) Hydroxyproline

C) Glycine

D) Lysine

21.Keratins, collagen, and elastin are examples of which type of protein?

A) Globular proteins

B) Conjugated globular proteins

C) Simple globular proteins

D) Fibrous proteins

22.Fibrous proteins are generally known to be insoluble in:

A) Distilled water

B) Dil. salt solution

C) Organic solvents

D) All common solvents such as water, dil. salt soln., dil. acids, alkalies and organic solvents

23.Which simple globular protein is soluble in distilled water?

A) Protamines

B) Albumin

C) Histones

D) Globulins

24.Globulins are classified as:

A) Water soluble simple globular proteins

B) Water insoluble globular proteins

C) Conjugated globular proteins

D) Fibrous proteins

25.Proteins combined with pigments are called:

A) Glycoproteins

B) Lipoproteins

C) Chromoproteins

D) Nucleoproteins

26.Mucin (in saliva) is an example of a conjugated globular protein combined with:

A) Lipids

B) Nucleic acid

C) Carbohydrates

D) Phosphoric acid

27.Casein of milk is an example of which type of conjugated protein?

A) Lipoprotein

B) Chromoprotein

C) Phosphoprotein

D) Metalloprotein

28.Denaturation of a protein is said to occur when the protein undergoes changes in:

A) Molecular weight only

B) Composition only

C) Structure or composition

D) Primary structure only

29.Denaturation primarily results in the unfolding of the protein molecule due to the destruction of:

A) Peptide bonds

B) Salt bridges by thermal agitation

C) Hydrogen bonds

D) Disulfide linkages

30.Which mineral acid causes denaturation by destroying salt bridges by altering the ionization of carboxyl and amino groups?

A) Nitric acid

B) Sulfosalicylic acid

C) Acetic acid

D) Citric acid

31.Mineral alkalies, such as sodium hydroxide, denature proteins by:

A) Thermal agitation

B) Oxidative decomposition

C) Cleavage of hydrogen bonds

D) Splitting peptide bonds

32.Neutral chemical agents, such as urea, cause protein denaturation by:

A) Splitting salt bridges

B) Mechanical deformation

C) Cleavage of hydrogen bonds

D) Splitting peptide bonds adjacent to aromatic rings

33.Amino acids react with ninhydrin to form a blue complex that maximally absorbs light at what wavelength?

A) 640 nm

B) 570 nm

C) 520 nm

D) 603 nm

34.The Biuret reaction tests for the presence of:

A) Aromatic rings

B) Alpha amino acids

C) Peptide linkages

D) Sulfhydryl groups

35.The Biuret reaction is dependent upon the formation of a complex involving:

A) Silver

B) Copper

C) Iron

D) Zinc

36.Albumin reacts specifically with Bromcresol green (BCG) at pH 4.1 to form what colored complex?

A) Purple

B) Yellow

C) Greenish-blue

D) Red

37.What is the process of movement of proteins in an electrical field called?

A) Chromatography

B) Nephelometry

C) Turbidimetry

D) Electrophoresis

38.What is the isoelectric pH (pI) of a protein?

A) The pH at which it carries maximum positive charge

B) The pH at which it is neutral and does not carry any charge

C) The pH at which it binds lipids

D) The pH at which it precipitates easily

39.What is the first step in the general metabolism of amino acids, where the amino group is transferred from an amino acid to a keto acid?

A) Deamination

B) Decarboxylation

C) Transamination

D) Urea cycle

40.Deamination, the removal of the amino group as NH3, results in the formation of:

A) A tripeptide and urea

B) A ketoacid and ammonia

C) Glutamic acid

D) Pyruvic acid

41.Oxidative deamination takes place mostly in which organs?

A) Spleen and pancreas

B) Heart and lungs

C) Liver and kidneys

D) Muscle and bone

42.The major oxidative deamination reaction is catalyzed by which mitochondrial enzyme?

A) Serum glutamate pyruvate transaminase (SGPT)

B) Pepsin

C) Glutamate dehydrogenase (GLD)

D) Trypsin

43.Ammonia derived from the deamination of alpha-amino acids is:

A) Non-toxic and excreted directly

B) Converted to urea in the kidneys

C) Toxic, and human tissues detoxify it by converting it to glutamate for transport to the liver

D) Stored in muscle tissue

44.The term “dynamic equilibrium” refers to the constant interchange between:

A) Essential and nonessential amino acids

B) Plasma proteins and labile tissue reserve

C) Serum albumin and globulin

D) Lipids and carbohydrates

45.The most common metabolic disorder in amino acid metabolism, caused by a deficiency of hepatic enzyme phenylalanine hydroxylase, is:

A) Albinism

B) Alkaptonuria

C) Phenylketonuria (PKU)

D) Wilson’s disease

46.What enzyme is defective in Phenylketonuria (PKU)?

A) Homogentisate oxidase

B) Tyrosinase

C) Phenylalanine hydroxylase

D) Glutamate dehydrogenase

47.Which disorder is caused by the deficiency of homogentisate oxidase in tyrosine metabolism, leading to urine that turns black or brown upon standing?

A) Phenylketonuria

B) Albinism

C) Alkaptonuria

D) Parkinson’s disease

48.The most common cause of Albinism is a defect in which enzyme?

A) Homogentisate oxidase

B) Tyrosinase

C) Phenylalanine hydroxylase

D) Ceruloplasmin

49.Parkinson’s disease is linked with decreased synthesis of which intermediate compound formed in tyrosine metabolism?

A) Melanin

B) Homogentisate

C) Dopamine

D) Tyrosine

50.What is the clinical condition in which increased amounts of proteins (detectable by usual chemical methods) are present in urine?

CORRECT ANSWERS

1. C

2. D

3. B

4. C

5. D

6. C

7. C

8. C

9. D

10. C

11. C

12. C

13. C

14. C

15. D

16. B

17. B

18. C

19. C

20. C

21. D

22. D

23. B

24. B

25. C

26. C

27. C

28. C

29. C

30. B

31. B

32. C

33. B

34. C

35. B

36. C

37. D

38. B

39. C

40. B

41. C

42. C

43. C

44. B

45. C

46. C

47. C

48. B

49. C

50. C

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