JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D I Year REMEDIAL BIOLOGY Previous Question Paper (October/November - 2019 - R08)

Membrane-bound organelles are specialized structures within plant cells that perform distinct physiological functions, allowing for compartmentalization of metabolic processes. The key organelles include:

1. Nucleus: The control center of the cell, enclosed by a double-membrane nuclear envelope with pores. It contains genetic material (DNA) and the nucleolus, which is the site of ribosome synthesis. It regulates gene expression and cell division.

2. Mitochondria: Known as the powerhouse of the cell, these are bounded by a double membrane, with the inner membrane folded into cristae. They are the primary sites of aerobic respiration, where ATP is generated through the Krebs cycle and electron transport chain.

3. Chloroplasts: Unique to plants, these contain chlorophyll and are enclosed by a double membrane. The internal structure consists of thylakoids stacked into grana, embedded in the stroma. They are the site of photosynthesis, converting light energy into chemical energy (glucose).

4. Endoplasmic Reticulum (ER): A network of membranous tubules and sacs. The Rough ER is studded with ribosomes and is involved in protein synthesis and folding, while the Smooth ER lacks ribosomes and is responsible for lipid synthesis and detoxification.

5. Golgi Apparatus: Composed of flattened sacs called cisternae. It functions as the processing, sorting, and packaging center for proteins and lipids synthesized in the ER, often modifying them before dispatching them to their final destinations via vesicles.

6. Vacuole: A large, membrane-bound sac known as the tonoplast. In mature plant cells, the central vacuole occupies most of the cell volume. It stores water, nutrients, pigments, and waste products, and maintains turgor pressure, which provides structural support to the plant.

7. Peroxisomes: Small, single-membrane vesicles containing oxidative enzymes. They play a crucial role in photorespiration, lipid metabolism, and the breakdown of toxic hydrogen peroxide into water and oxygen.