Cell Specialisation (1.1.3) PDF

Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate...

Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells). In animals, most cells only differentiate once, but in plants many cells retain the ability. Examples of specialised cells in animals Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells). In animals, 1 most cells only differentiate once, but in plants many cells retain the ability.  1. Sperm cells: specialised to carry the male’s DNA to the egg cell (ovum) for successful reproduction Streamlined head and long tail to aid swimming Many mitochondria (where respiration happens) which supply the energy to allow the cell to move The acrosome (top of the head) has digestive enzymes which break down the outer layers of membrane of the egg cell 2. Nerve cells: specialised to transmit electrical signals quickly from one place in the body to another The axon is long, enabling the impulses to be carried along long distances Having lots of extensions from the cell body (called dendrites) means branched connections can form with other nerve cells The nerve endings have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters. These allow the impulse to be passed from one cell to another. 3. Muscle cells: specialised to contract quickly to move bones (striated muscle) Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells). In animals, 2 most cells only differentiate once, but in plants many cells retain the ability.  or simply to squeeze (smooth muscle, e.g found in blood vessels so blood pressure can be varied), therefore causing movement Special proteins (myosin and actin) slide over each other, causing the muscle to contract Lots of mitochondria to provide energy from respiration for contraction They can store a chemical called glycogen that is used in respiration by mitochondria Examples of specialised cells in plants 4. Root hair cells: specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots Have a large surface area due to root hairs, meaning more water can move in The large permanent vacuole affects the speed of movement of water from the soil to the cell Mitochondria to provide energy from respiration for the active transport of mineral ions into the root hair cell 5. Xylem cells: specialised to transport water and mineral ions up the plant from the roots to the shoots Upon formation, a chemical called lignin is deposited which causes the cells Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells). In animals, 3 most cells only differentiate once, but in plants many cells retain the ability.  to die. They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water 6. Phloem cells: specialised to carry the products of photosynthesis (food) to all parts of the plants Cell walls of each cell form structures called sieve plates when they break down, allowing the movement of substances from cell to cell Despite losing many sub-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells. Cell Specialisation (1.1.3) Cells specialise by undergoing differentiation: a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role. Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells). In animals, 4 most cells only differentiate once, but in plants many cells retain the ability.