Problem 55 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following biomolecules contain nontransition metal ion? (a) vitamin \(\mathrm{B}_{12}\) (b) chlorophyll (c) haemoglobin (d) insulin

Step-by-Step Solution

Answer

Chlorophyll contains a nontransition metal ion (magnesium).

Step 1: Understand Metal Ions in Biomolecules

Biomolecules often contain metal ions which play critical roles in their structure and function. Transition metals like iron, copper, and zinc are commonly found in biomolecules, but nontransition metals such as magnesium and sodium can also occur.

Step 2: Identify the Metal Ion in Vitamin 9_{ ext{12}}

Vitamin 9_{ ext{12}} contains cobalt, which is a transition metal. It is not a candidate for the biomolecule containing a nontransition metal ion.

Step 3: Identify the Metal Ion in Chlorophyll

Chlorophyll contains a magnesium ion at its core. Magnesium is a nontransition metal, making chlorophyll a biomolecule with a nontransition metal ion.

Step 4: Identify the Metal Ion in Haemoglobin

Haemoglobin contains iron ions, which are transition metals. Therefore, haemoglobin does not contain a nontransition metal ion.

Step 5: Check Insulin for Metal Ions

Insulin doesn't typically require metal ions for its primary function in glucose metabolism. However, it sometimes interacts with zinc ions, which are transition metals.

Step 6: Conclusion

Based on the analysis, chlorophyll is the biomolecule containing a nontransition metal ion (magnesium).

Key Concepts

Nontransition Metal Ions

Nontransition metal ions are elements found on the periodic table that do not belong to the transition metal category, which typically consists of groups 3 to 12 on the periodic table. Nontransition metals include elements such as magnesium, calcium, and sodium. These metals often possess stable electron configurations and do not have unfilled d orbitals.

In biomolecules, nontransition metal ions frequently play essential roles. They can contribute to the stability and function of biological structures. For instance:

• Magnesium ions are integral to the structure of chlorophyll.
• Calcium ions are vital for bone structure and muscle function.
• Sodium ions are crucial for nerve impulse transmission and maintaining cellular fluid balance.

Understanding the distinction between transition and nontransition metal ions is vital in fields like biochemistry, where these ions participate in diverse biological processes.

Chlorophyll

Chlorophyll is a critical biomolecule for life on Earth, mostly known for its role in photosynthesis. It gives plants their green color and is essential for converting sunlight into chemical energy. One of the fascinating aspects of chlorophyll is its structure, featuring a magnesium ion at its core.

Chlorophyll's structure, known as a porphyrin ring, forms the basis for its functionality. The central magnesium ion plays a pivotal role in stabilizing this ring-shaped structure:

• It helps capture light energy, which is necessary for photosynthetic processes.
• The ion enables the efficient transfer of energy within the chlorophyll molecule.

Understanding chlorophyll and its magnesium ion not only sheds light on the photosynthetic process but also emphasizes the importance of nontransition metals in natural functions.

Magnesium in Biomolecules

Magnesium (mg) is a versatile nontransition metal ion that appears in a wide range of biomolecules. It is vital for numerous physiological and biochemical processes due to its role as a cofactor for many enzymes and its involvement in nucleic acid function.

In biomolecules, magnesium ions can combine with other functional groups to stabilize structures and facilitate reactions:

• In DNA and RNA, magnesium ions help stabilize the negatively charged phosphate backbones, allowing these molecules to maintain their structure.
• They are essential activators of almost all enzymes involved in phosphate transfer reactions.
• By binding to substrates, magnesium can assist in the catalysis of biochemical reactions.

The importance of magnesium in biomolecules cannot be overstated, and its role in chlorophyll underscores this point. These contributions illustrate why magnesium is fundamental to both plant and animal life, making it a crucial component of many biological systems.