Biology · Chemistry

Biomolecules and Enzymes

1,432 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Specific enzymes are needed for the break-down of a particular substance.

  1. True

  2. False

  3. Either

  4. Neither
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Enzymes are very specific for the substances they act upon and cause their breakdown. For example, cellulase enzyme breakdowns cellulose, protease enzyme breakdowns proteins, pectinase enzyme breakdowns pectin, hemicellulose enzyme breakdowns hemicellulose and many more such enzymes are there. Enzymes are biological catalysts which increase the rate of reaction by lowering the energy of activation. High specificity is a characteristic feature of enzymes.
Hence, the statement given in the question is correct.
So, the correct answer is 'True'
Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

The active site of an enzyme is formed by

  1. Exposed sulphur bonds

  2. Side chains of the amino acids

  3. Amino groups of the amino acids

  4. Carboxyl group of the amino acids
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The enzyme active site is composed of the amino acid residues. Side chains of the amino acids are seen in the active site region of the enzyme. The difference in the identity, charge, and spatial orientation of the functional groups located there results in the difference in enzyme specificity. 

So, the correct option is ' side chains of amino acids'.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

Identify the incorrect statement about enzymes.

  1. They consist of proteins, with or without a non-protein part.

  2. They change the rate of the catalyzed reaction.
  3. They change the value of $\triangle$G of the reaction.

  4. They are not sensitive to heat.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are biological catalyst which catalyze biological reactions. Most of the enzymes are proteins in nature. Some of the enzymes have non protein part which helps them to carry out reaction. Enzymes change the rate of chemical reaction by bringing about a decrease in free energy requirement. Thus, changing the free energy of the reaction. Because enzymes are proteins, they are highly sensitive to heat. Thus, enzymes catalyze reactions only at physiological conditions of temperature and pH.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

What is true for an enzyme during a biochemical reaction?

  1. It becomes part of the product

  2. It is unchanged

  3. It is broken down into amino acids

  4. It reacts with fatty acids

  5. It becomes a polypeptide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Any chemical reaction includes the formation of transition state between reactant and product. The energy required for formation of the transition state is termed as activation energy. Enzymes enhance the rate of reaction by lowering down the activation energy of transition state but themselves remain unchanged. Thus, the correct answer is option B.

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

The action of lysozyme is

  1. Physiological

  2. Anatomical

  3. Morphological

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lysozyme are also reffered as muramidase. They are glycoside hydrolases. They catalyzes hydorlysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetly-D-glucosamine residues in peptidoglycan thus they can dissolve bacterial cell wall. It is present  in a number of secretions, such as tears, saliva, human milk and mucus. So, its function is physiological.
Thus, the correct answer is option (A).

Multiple choice properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology
Holoenzyme is the complete enzyme consisting of an apoenzyme and a co-factor. Select the option that correctly identifies the nature of apoenzyme and co-factor.

  1. Apoenzyme - Protein
    Co - factor - Non-Protein

  2. Apoenzyme - Non - Protein
    Co - factor - Protein

  3. Apoenzyme - Protein
    Co - factor - Protein

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conjugated enzymes ( holoenzymes) are formed of two parts a protein part called apoenzyme and a non-protein part named co-factor. The complete conjugated enzyme consisting of an apoenzyme and a co-factor is called holoenzyme. Holoenzyme is the functional unit of enzyme. 

${\underset{(active\,\, enzyme)}{Holoenzyme}}$ $\rightarrow$  ${\underset {(protein\,\, part)}{Apoenzyme}}$ $+ co-factor$
Co-factor may be inorganic or organic in nature. Catalystic activity is lost when co-factor is removed from the enzyme which indicates that it plays a crucial role in catalytic activity of enzymes.
So, the correct answer is 'Apoenzyme - Protein, Co - factor - Non-Protein'.

Multiple choice zoology biotechnology and its applications transgenic animals transgenic organisms applications of biotechnology

A human protein which is obtained from transgenic animals and is used to treat emphysema is 

  1. Alpha-lactalbumin

  2. Thyroxine
  3. $\alpha-1$-antitrypsin

  4. Insulin.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A human protein which is obtained from transgenic animals and is used to treat emphysema is α−1-antitrypsin. Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA which codes for particular product such as human proteins. 

So, the correct option is 'Option C' .

Multiple choice zoology aids to health immunity and the lines of immunity immune system of the body immunity and blood groups

Which one forms chemical barrier for infections?

  1. Isozyme

  2. Coughing

  3. Lysozyme

  4. Lysosome
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase is an antibacterial enzyme produced by animals and humans that forms part of the innate immune system. Lysozyme is abundant in secretions including tears, saliva, human milk, sweat and mucus. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils. Lysozyme is an enzyme and hence, acts as a chemical barrier of infection.

So, the correct answer is 'Lysozyme'.

Multiple choice biology tissues muscle tissue structure of protein muscle tissues

Which one is both structural and functional (catalytic) protein?

  1. Hexokinase

  2. Myosin

  3. Ribozyme

  4. Acetyl Co-A
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Myosin is found in muscle filaments. The head portion of myosin forms cross linkage with actin filaments during muscular contraction. The cross bridges between actin and myosin are very important for muscular contraction activity. Thus, myosin fulfills both structural and functional roles.

Multiple choice bio-chemistry proteins muscle tissue structure of protein muscle tissues

An example of structural protein is

  1. Myosin

  2. Collagen

  3. Keratin

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Structural proteins are fibrous proteins and form the largest class of proteins measured in terms of their total mass. Structural proteins include myosin, collagen, and keratin. 

Keratins form the protective covering like skin, hair, fur, wool, etc. in all land vertebrates. Equally widespread are the actin and myosin proteins of muscle tissue that play a major role in body movements. In addition, there are the collagens of tendons and hides, which form connective ligaments within the body.
Thus, the correct answer is option (D), 'All of the above'.

Multiple choice zoology immunity phagocytosis cells in immune system immune system, its cells, mediators and antigens

Antigenic determinants are 

  1. Large and complex molecules that are different from those of an organism/host

  2. Proteins or carbohydrates

  3. Recognisable sites over antigens

  4. Specific products of pathogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that binds to the epitope is called a paratope. These epitopes interact with the paratope based on the 3-D surface features and shape or tertiary structure of the antigen.

So, the correct answer is 'Recognisable sites over antigens'.