Osmosis is the movement of water across a semi-permeable membrane. Osmosis is a selective process since the membrane does not allow all molecules to pass through it. Water is usually the only free flowing molecule across this membrane.
Isotonic, hypotonic solutions, hypertonic solutions
- Isotonic solutions are those which have the same solute and pH concentration as the surrounding body fluid or the cytoplasm.
- Hypotonic solutions contain lesser amount of solute concentration compared to the surrounding fluid and can force the cell to rupture due to excess input of water into the cell.
- Hypertonic solutions contain a higher concentration of solute compared to the surrounding fluid and thus push water out of the cell, shrinking it.
Cell walls in plants
Plant cells are different from animal cells due to the presence of a cell wall. The cell wall is made of cellulose and gives a rigid structure to the plant cell. It provides structural support to plants. Due to cell walls, cells of plants, fungi and bacteria can withstand greater changes in surrounding conditions than animal cells. E.g. Cell wall enables the cells to withstand hypotonic solution without bursting.
Cell Organelles
Eukaryotic cells contain various membrane-bound organelles that carry out various functions in the cell, e.g. Nucleus, Endoplasmic reticulum, Golgi apparatus, Lysosomes, etc.
Endocytosis
Endocytosis is the invagination of the cell membrane, followed by pinching off forming a membrane-bound vesicle. This is commonly seen in Amoeba.
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