Match the following list of bioactive substances a – Class 12 Biology

NCERT Exemplar · Q6

Q. Match the following list of bioactive substances and their roles: Bioactive Substance — Role A. Statin — i. Removal of oil stains B. Cyclosporin A — ii. Removal of clots from blood vessels C. Streptokinase — iii. Lowering of blood cholesterol D. Lipase — iv. Immuno-suppressive agent Choose the correct match:

(a) A-ii, B-iii, C-i, D-iv

(b) A-iv, B-ii, C-i, D-iii

(d) A-iii, B-iv, C-ii, D-i

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Concept understanding — Antibiotic Producing Fungi

Imagine you have a wound that gets infected. Before the 20th century, that infection could easily kill you. Today, we have a weapon against such bacterial infections: antibiotics. The most famous antibiotic, penicillin, comes from a humble source — a fungus.

The intuition is simple: in nature, fungi and bacteria are rivals. They compete for the same food and space. To win this battle, some fungi have evolved a chemical weapon. They produce a substance that kills bacteria or stops them from growing. That substance is an antibiotic. So, an antibiotic-producing fungus is simply a fungus that manufactures a natural chemical to destroy or weaken bacteria.

The precise meaning is this: certain species of fungi (like Penicillium notatum or Cephalosporium acremonium) secrete secondary metabolites — chemicals not essential for their own growth — that are toxic to bacteria. These chemicals interfere with a bacterium's cell wall, its protein-making machinery, or its DNA replication. Because bacterial cells are structurally different from human cells, the antibiotic can often kill the invader without harming us.

Why does this matter? It is the foundation of modern medicine. The discovery of penicillin by Alexander Fleming in 1928 was a turning point. Before antibiotics, a simple scratch could lead to sepsis. Today, antibiotics from fungi save millions of lives every year. They are used to treat pneumonia, tuberculosis, wound infections, and many other bacterial diseases.

Important

Antibiotics are effective only against bacteria, not against viruses (like the common cold or flu). Taking an antibiotic for a viral infection is useless and contributes to a serious problem called antibiotic resistance — where bacteria evolve to become immune to the drug.

Here are the key points to remember:

Source: The most famous antibiotic-producing fungus is Penicillium, which gives us penicillin. Another is Cephalosporium, which produces cephalosporins. …

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Bioactive substances like statins, cyclosporin A, streptokinase, and lipases, often derived from microbes, play crucial roles in medicine and industry, from lowering cholesterol to removing stains.

The world of microorganisms, though invisible to the naked eye, is a powerhouse of biochemical activity, yielding a vast array of substances with profound impacts on human welfare. Among these are bioactive molecules, which are compounds that have a specific effect on living organisms or biological systems. Many of these are produced by fungi and bacteria and have found indispensable applications in medicine, industry, and biotechnology. Understanding their origins and functions is key to appreciating their significance.

Let's delve into the specific bioactive substances mentioned and their roles:

Statins: These are a class of drugs produced by the yeast Monascus purpureus. Their primary medical application is in managing hypercholesterolemia, a condition characterized by high levels of cholesterol in the blood.
- Role: Statins function by competitively inhibiting the enzyme HMG-CoA reductase, which is crucial for the synthesis of cholesterol in the liver. By blocking this enzyme, statins effectively reduce the body's ability to produce cholesterol, thereby lowering blood cholesterol levels. This action is vital in preventing cardiovascular diseases like heart attacks and strokes.
Important

Statins are a classic example of a microbial product used as a blood-cholesterol lowering agent, highlighting the therapeutic potential of fungi.
Cyclosporin A: This powerful immunosuppressive agent is produced by the fungus Trichoderma polysporum. Its discovery revolutionized organ transplantation.
- Role: In organ transplant patients, the recipient's immune system often recognizes the transplanted organ as foreign and mounts an immune response to reject it. Cyclosporin A works by selectively suppressing the activity of T-lymphocytes, which are key immune cells responsible for cell-mediated immunity and graft rejection. By dampening this immune response, Cyclosporin A significantly increases the success rate of organ transplants, allowing the body to accept the new organ.
Note

The ability of Cyclosporin A to specifically target T-lymphocytes makes it a valuable tool, as it reduces the risk of rejection without completely shutting down the entire immune system, which would leave the patient vulnerable to infections.
Streptokinase: Unlike the previous two, which are fungal products, Streptokinase is an enzyme produced by the bacterium Streptococcus. It has a critical role in emergency medicine. …

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