NEET Botany: Cell Structure and Functions

The Endoplasmic Reticulum (ER)

• Primary function: Plays a crucial role in protein and lipid synthesis, and is also involved in detoxification processes within the cell.
• Rough ER: Studded with ribosomes responsible for protein synthesis
• Smooth ER: Lacks ribosomes and is involved in lipid and steroid hormone synthesis, detoxification, and calcium storage.

Lysosomes: The Recycling Center of the Cell

• Acidic pH maintenance: Lysosomes maintain a highly acidic internal environment (pH 4.5-5.0) achieved through specialized proton pumps that actively transport hydrogen ions (H+) into the lysosome.
• Membrane: Lysosomes are enclosed by a single membrane called the lysosomal membrane.
• Function: Lysosomes are responsible for the breakdown and digestion of cellular waste, debris, foreign substances, and even worn-out organelles. They act as the cell's recycling center, ensuring the efficient disposal and reuse of cellular components.
• Enzymes: Lysosomes contain a variety of powerful hydrolytic enzymes like proteases, lipases, nucleases, and glycosidases, which function optimally in acidic conditions.
• Suicidal bag: The lysosome is also called the "suicidal bag of the cell" because when the cell undergoes programmed cell death (apoptosis), lysosomes release their enzymes, leading to the breakdown of cellular components.

The Golgi Apparatus: The Packaging and Sorting Center

• Cis face: The cis face of the Golgi apparatus is responsible for receiving materials from the endoplasmic reticulum (ER).
• Function: The Golgi apparatus functions as a sophisticated processing and packaging center for proteins and lipids, modifying and sorting them for delivery to their specific destinations within the cell or for export outside the cell.

Vacuoles

• Membrane: Vacuoles are enclosed by a single membrane known as the tonoplast.
• Function: Vacuoles offer a diverse range of functions, including storage of water, nutrients, waste materials, and pigments. They also play a role in maintaining turgor pressure in plant cells.