As i'm not so good in biology, and lazy to open up biology book and read it, i decided to post some information about any chapter here, but don't worry, all information i take from reference book :)
Properties of plasma mebrane:
- The cell membrane is describe as semi-permeable membrane or partially permeable membrane, It means that only certain substances can move across it freely but other substances cannot.
- Hydrophilic head, like water.. Hydrophobic tail dislike water. (Phobia)
- Passive transport:
- Simple diffusion: Movement of molecules from a region of higher concentration to a region lower concentration.
- Facilitated diffusion: Movement of bigger molecules which are not soluble in lipids down the concentration gradient. Example: amino acid,glucose.. Need carrier protein where their active site complements the respective molecules.
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- Osmosis : Movement of water molecules across the plasma membrane from a region of lower concentration to a region of higher concentration. Example: water
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2. Active Transport
- Movement of substances across the plasma membrane against the concentration gradient
- Needs protein carriers
- Needs energy. ATP
- When a cell is surrounded by an external solution that is more dilute than the cytoplasm vacuole, the external solution is said to hypotonic to the cell. A cell is hypotonic solution will gain water by osmosis
- A hypotonic refers to a solution that is less solute (more water) compared to a cytoplasm of the cell. If the solution surrounding the cell is hypotonis osmosis causes water to have a net flow into the cell. Thus, resulting in the swelling and expension of the cell
- Haemolysis will occur.
- PLANT CELLS IN A HYPOTONIC SOLUTION
1. When a plant cell is immersed in a hypotonic solution such as water, water molecules diffuse into the cell by osmosis.
2. The vacuole gain water, expands and exerts pressure outwards on the cell wall.
3. This pressure is called turgor pressure which cause the plant cell to become turgid.
4. The turgidity of the cells give the plant mechanical support.
Isotonic
- Isotonic solution is the solution which the concentration of solute is equal.
- A cell in isotonic solution neither gains nor loses water by osmosis
- PLANT CELLS IN AN ISOTONIC SOLUTION
1. If a plant cell is immersed in an isotonic solution such as 5% sucrose solution, there is no net movement of water across the plasma membrane.
2. Water flows across the membrane at the same rate in both directions.
3. The cell's volume and shape remain constant.
Hypertonic
- PLANT CELLS IN A HYPERTONIC SOLUTION
1. When a plant cell is placed in a hypertonic solution such as 30% sucrose solution, water molecules diffuses out of the cell by osmosis.
2. Water is lost from the vacuole and cytoplasm.
3. The vacuole and the cytoplasm shrink. The plasma membrane is pulled away from the cell wall.
4. The plant cell becomes flaccid and the plant wilts.
5. This process is called plasmolysis.
6. If the plasmolysed plant cell is immersed in a hypotonic solution, there is a net movement of water into the cell. The cell will expand and become turgid again.
7. This process is called deplasmolysis.
Sumber Rujukan: Focus excel, blogger biology
