Cell - Structure and Functions — Important Questions

Ribosomes

Ribosomes are responsible for protein synthesis in cells. They are small granular structures made of RNA and proteins that read the genetic code from messenger RNA (mRNA) and assemble amino acids into proteins. Ribosomes can be found free in the cytoplasm or attached to the endoplasmic reticulum. Lysosomes digest cellular waste, vacuoles store materials, and chloroplasts carry out photosynthesis. Protein synthesis is essential for cell growth, repair, and enzyme production.

Plasma membrane

The cell membrane is also known as the plasma membrane. It is the outermost boundary of animal cells and lies just inside the cell wall in plant cells. The plasma membrane controls what enters and exits the cell, making it selectively permeable. The nuclear membrane surrounds the nucleus, the cell wall is an external rigid layer in plants, and cytoplasm is the gel-like substance inside the cell. The plasma membrane is crucial for maintaining cell shape and protecting the cell's interior.

Suicidal bags of the cell

Lysosomes are known as 'suicidal bags of the cell' because they contain powerful digestive enzymes that can break down cellular waste and damaged organelles. When a cell is damaged beyond repair or no longer needed, lysosomes can burst and release these enzymes to digest the entire cell, leading to programmed cell death. Mitochondria are the powerhouse, chloroplasts are sometimes called the kitchen, and the nucleus is the control room. This self-destructive capability of lysosomes is essential for cellular maintenance and tissue development.

Robert Brown

Robert Brown first named the nucleus in 1831. He observed this dark-colored structure in plant cells and called it the nucleus, though he didn't fully understand its functions at that time. Robert Hooke discovered cells, Rudolf Virchow contributed to cell theory by stating that all cells come from pre-existing cells, and Camillo Golgi discovered the Golgi complex. Brown's identification of the nucleus was crucial for understanding cell structure and later led to the discovery of its role in controlling cell functions and containing genetic material.