d-block elements (transition metals) play important roles in biological systems because they can exist in multiple oxidation states and form stable complexes with biomolecules. Here’s a breakdown:
1. Iron (Fe)
- Part of hemoglobin and myoglobin, which transport and store oxygen in the blood and muscles.
- Involved in electron transport and energy production in cells (cytochromes).
2. Copper (Cu)
- Part of enzymes like cytochrome oxidase and superoxide dismutase, which help in cellular respiration and antioxidant defense.
- Helps in the formation of collagen and pigments like melanin.
3. Manganese (Mn)
- Activates enzymes involved in photosynthesis, especially photosystem II.
- Helps in metabolism of carbohydrates, proteins, and lipids.
4. Cobalt (Co)
- Component of vitamin B12 (cobalamin), essential for red blood cell formation and DNA synthesis.
5. Zinc (Zn)
- Present in over 300 enzymes like carbonic anhydrase and alcohol dehydrogenase.
- Supports immune function, growth, and wound healing.
6. Molybdenum (Mo)
- Part of enzymes like nitrogenase, which helps in nitrogen fixation in plants.
- Involved in metabolism of sulfur-containing amino acids.
7. Other Roles
- Chromium (Cr) helps regulate glucose metabolism.
- Vanadium (V) is found in some marine organisms and may help in enzyme function.
✅ In short:
d-block elements are essential for oxygen transport, enzyme function, electron transfer, metabolism, and growth. Without them, many vital biological processes cannot occur.