Ch 5 dives deep into cell biology. Students study the plasma membrane, nucleus, and all major organelles, understanding how each contributes to the cell's functioning as the basic unit of life.
Plasma membrane: thin, flexible, selectively permeable (controls entry/exit of substances via diffusion, osmosis). Nucleus: contains chromosomes (DNA), nucleolus, and nuclear membrane with pores. It directs all cell activities. Prokaryotic cells lack a well-defined nucleus; eukaryotic cells have one.
Endoplasmic reticulum (ER): smooth ER makes lipids, rough ER has ribosomes that make proteins. Golgi apparatus: packages and dispatches proteins/lipids. Lysosomes: digestive enzymes — break down foreign material and worn-out organelles (suicide bags). Mitochondria: cellular respiration — powerhouse of the cell. Chloroplast: photosynthesis in plants.
Download: https://ncert.nic.in/textbook/pdf/iesc105.pdf | Complete book: https://ncert.nic.in/textbook/pdf/iesc1ps.zip
Lysosomes contain powerful digestive enzymes. If a cell is damaged beyond repair, lysosomes burst and release these enzymes, digesting the cell itself. This self-destruction process is called autolysis. This is why lysosomes are called "suicide bags" of the cell.
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