Problem 52 - A Complete Resource Book in Chemistry for JEE Main

Question

\(\mathrm{Mg}\) is an important component of which biomolecule occurring extensively in living world? (a) cholorophyll (b) haemoglobin (c) ATP (d) florigen

Step-by-Step Solution

Answer

Magnesium is an important component of chlorophyll.

Step 1: Understand the Question

The question asks which biomolecule contains magnesium (Mg) as a significant component. Among the options provided, magnesium should be a notable and essential element in the structure or function of the correct biomolecule.

Step 2: Recall Biological Molecules and Their Components

Recall that chlorophyll is a pigment found in plants that is crucial for photosynthesis. Haemoglobin is found in blood and carries oxygen. ATP is an energy molecule used in cells. Florigen is hypothesized to be a flowering signal in plants.

Step 3: Identify the Biomolecule with Magnesium

Recall that chlorophyll specifically contains a magnesium ion at its center, which is essential for capturing light energy during photosynthesis. This magnesium ion is a distinctive feature of chlorophyll molecules.

Step 4: Match Options with Knowledge

Among the options, consider which biomolecule you know to have magnesium as a critical component. Chlorophyll (option a) matches this description, as it contains magnesium at its core.

Key Concepts

Chlorophyll

Chlorophyll is a vibrant green pigment found inside the chloroplasts of plant cells and some algae. It plays a crucial role in capturing light energy from the sun, enabling the process of photosynthesis. The structure of a chlorophyll molecule is fascinating. At its core lies a magnesium ion (\( \mathrm{Mg} \)) which is bonded within a large ring structure called a porphyrin ring.

This magnesium ion is essential because it holds a key position in capturing light energy. Once the light energy is absorbed, it enables the plant to convert light into chemical energy. Therefore, it is magnesium in chlorophyll that makes the pigment uniquely efficient at its function.

• The central magnesium ion is surrounded by a hydrophobic tail, helping chlorophyll anchor into the lipid membranes of chloroplasts.
• Chlorophyll molecules are sensitive to specific wavelengths, primarily absorbing blue and red light while reflecting green, giving plants their typical color.

Understanding chlorophyll's structure and its relationship with magnesium can help one appreciate why magnesium is vital for the process of photosynthesis.

Photosynthesis

Photosynthesis is a fundamental biological process where plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored as glucose. This process is crucial for sustaining life on Earth, as it provides both food and oxygen.

The chemical reaction for photosynthesis can be translated simply as: carbon dioxide \( (\mathrm{CO}_2)\), water \( (\mathrm{H}_2\mathrm{O}) \), and sunlight are converted into glucose \( (\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6}) \) and oxygen\( (\mathrm{O}_2)\).

The process primarily takes place in the chloroplasts of plant cells, where chlorophyll pigments absorb sunlight. The role of magnesium in chlorophyll cannot be understated as it is a pivotal part of the light-absorbing complex. Key stages in photosynthesis include:

• Light-dependent reactions: These occur in the thylakoid membranes, where light energy is captured by chlorophyll and used to generate ATP and NADPH.
• Light-independent reactions (Calvin cycle): These occur in the stroma of the chloroplasts, where ATP and NADPH are used to convert \( \mathrm{CO}_2 \) into glucose.

By understanding photosynthesis, we grasp the intricate dependencies between light energy, chlorophyll, and essential biochemical pathways that sustain life.

Biological Molecules

Biological molecules, also known as biomolecules, are the building blocks of life. They are essential components of all living organisms and include various categories: carbohydrates, proteins, lipids, and nucleic acids. Each type of biomolecule plays a unique and critical role in the functioning of cells and organisms as a whole.

Magnesium holds a place of importance in several biological molecules, chiefly for its role in stabilizing structures and participating in biochemical reactions. In chlorophyll, magnesium's role is central to light absorption in photosynthesis.

• Carbohydrates: These offer energy to living cells and provide structural support in plant cell walls as cellulose.
• Proteins: Comprised of amino acids, proteins perform numerous roles including catalyzing biochemical reactions as enzymes and providing cellular structure.
• Lipids: Insoluble in water, these biomolecules store energy, build cellular membranes, and serve as signaling molecules.
• Nucleic Acids: DNA and RNA are essential for genetic information storage and transmission.

By recognizing the interrelated nature of biomolecules, one understands the complexity and beauty of life at its most fundamental level, with magnesium playing a critical part particularly in photosynthetic processes.