Biology And Human Welfare

Streptokinase is an enzyme widely used in the medical field, particularly for its ability to treat blood clot-related conditions. The correct answer to the question is:

Removing clot from blood vessels. Understanding the mechanism of streptokinase helps in comprehending its clinical use:

• Streptokinase catalyzes the conversion of plasminogen to plasmin. Plasmin is an enzyme that dissolves fibrin clots.
• This property makes streptokinase particularly useful in conditions such as acute myocardial infarction, deep vein thrombosis, and pulmonary embolism, where dissolving blood clots can be life-saving.
• In clinical settings, streptokinase is administered intravenously to rapidly break down these clots and restore normal blood flow.

The disorder caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the hemoglobin is known as Sickle-cell Anemia.

In the normal beta-globin chain of hemoglobin, the sixth amino acid is Glutamic acid. In Sickle-cell Anemia, due to a genetic mutation, Glutamic acid is replaced by Valine. This substitution leads to the production of abnormal hemoglobin known as hemoglobin S (HbS).

Explanation of the mutation process:

• Normal hemoglobin (HbA): In a healthy individual, the beta-globin chain sequence includes Glutamic acid at the sixth position. This ensures the normal disc shape of red blood cells and their functionality.
• Mutant hemoglobin (HbS): The mutation from Glutamic acid (hydrophilic) to Valine (hydrophobic) causes hemoglobin to polymerize under low oxygen conditions, leading to distorted sickle-shaped red blood cells.
• These sickle-shaped cells cause blockages in blood vessels and are prone to destruction, resulting in anemia and various complications associated with Sickle-cell Anemia.

This genetic disorder illustrates the importance of amino acid sequencing in protein function and the profound impact that a single amino acid substitution can have on overall health.

In the Hershey and Chase experiment, radioactive isotopes were used to label different components of the bacteriophage, a virus that infects bacteria. The two isotopes used were ³⁵S and ³²P. These isotopes were crucial in determining the nature of genetic material.

• ³⁵S (Sulfur-35): This isotope was used to label proteins. Sulfur is found in the amino acids cysteine and methionine, which are components of proteins, but not in nucleic acids.
• ³²P (Phosphorus-32): This isotope was used to label DNA. Phosphorus is a key component of the phosphate backbone of nucleic acids, but not a constituent of amino acids and proteins.

The experiment involved growing bacteriophages in a medium that contained either ³⁵S or ³²P, allowing them to incorporate the radioactive isotopes into their structure.

When these radioactively-labeled bacteriophages infected bacteria, Hershey and Chase were able to demonstrate that phosphorus (associated with DNA) entered the bacterial cells while sulfur (associated with proteins) did not. This provided strong evidence that DNA, not protein, was the material responsible for heredity.

ELISA, which stands for Enzyme-Linked Immunosorbent Assay, is a common laboratory technique used to detect and measure antibodies or antigens in a sample. The fundamental principle of ELISA is based on Antigen – Antibody interaction. This interaction is highly specific, allowing for the detection of particular proteins. The process involves the following key steps:

1. An antigen or antibody is immobilized on a solid surface.
2. A sample containing antibodies (or antigens) is added, where it will bind to the immobilized antigen (or antibody) if the target is present.
3. An enzyme-linked secondary antibody is then added, which binds to the primary antibody (if detecting antigens) or directly to the antigen (if detecting antibodies).
4. A substrate is introduced, which reacts with the enzyme to produce a detectable signal, typically a color change.

The specificity and sensitivity of the Antigen – Antibody interaction in ELISA make it a powerful tool in diagnostics and research, particularly in detecting diseases, allergens, and hormones.