Why are mitochondria and chloroplasts called semi-autonomous organelles?

Mitochondria and chloroplasts have their own circular DNA (similar to bacterial DNA) and their own 70S ribosomes. They can synthesize some of their own proteins. However, they depend on the nucleus for most proteins and cannot reproduce independently outside the cell — hence 'semi-autonomous'. This supports the Endosymbiotic Theory.

What is the function of the Golgi apparatus?

Golgi apparatus processes, modifies, packages, and dispatches proteins and lipids. Proteins from RER enter the cis face, are glycosylated/modified in the cisternae, and packaged into vesicles at the trans face for secretion or delivery to lysosomes. It also produces glycoproteins for the cell membrane.

Why are lysosomes called 'suicide bags'?

Lysosomes contain ~40 types of hydrolytic enzymes that can digest all biological macromolecules (proteins, lipids, carbohydrates, nucleic acids). Under stress or at the end of a cell's life, lysosomes can rupture and release these enzymes, digesting the entire cell — hence 'suicide bags'. This process is called autolysis.

Cell Organelles and Their Functions

Cell: The Unit of Life • Class 11 Biology • NCERT • CBSE

Key cell organelles: Mitochondria (powerhouse — ATP synthesis via cellular respiration), Chloroplast (photosynthesis in plant cells), Ribosome (protein synthesis — 80S in eukaryotes), Golgi Apparatus (packaging and secretion), ER (protein/lipid synthesis), Nucleus (controls all cell activities).

Frequently Asked Questions

Why are mitochondria and chloroplasts called semi-autonomous organelles?: Mitochondria and chloroplasts have their own circular DNA (similar to bacterial DNA) and their own 70S ribosomes. They can synthesize some of their own proteins. However, they depend on the nucleus for most proteins and cannot reproduce independently outside the cell — hence 'semi-autonomous'. This supports the Endosymbiotic Theory.
What is the function of the Golgi apparatus?: Golgi apparatus processes, modifies, packages, and dispatches proteins and lipids. Proteins from RER enter the cis face, are glycosylated/modified in the cisternae, and packaged into vesicles at the trans face for secretion or delivery to lysosomes. It also produces glycoproteins for the cell membrane.
Why are lysosomes called 'suicide bags'?: Lysosomes contain ~40 types of hydrolytic enzymes that can digest all biological macromolecules (proteins, lipids, carbohydrates, nucleic acids). Under stress or at the end of a cell's life, lysosomes can rupture and release these enzymes, digesting the entire cell — hence 'suicide bags'. This process is called autolysis.

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