Cell Specialisation
As an organism grows and develops cells have to perform different jobs. To perform these jobs more effectively cells begin to differentiate and become specialised. This means it gains different sub-cellular structures that enable it to carry out particular functions. You need to know the different examples below:
Specialised Animal Cells
Sperm Cells
Sperm cells contain the genetic information from the male parent and need to reach the egg cell, break into it and then fertilise it.
To allow them to do this they have multiple adaptations:
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- A large nucleus containing the genetic information to be passed on.
- A long tail that can whip from side to side to assist with movement.
- The mid-section is full of mitochondria to transfer energy for movement.
- The acrosome contains digestive enzymes to break down the outer layer of the egg.
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Nerve Cells
Nerve cells transmit electrical impulses around the body. To allow them to do this they have multiple adaptations:
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- A long axon to carry information over long distances.
- Numerous dendrites to pass information to neighbouring nerve cells.
- The synapses are adapted to pass impulses to other nerve cells using special neurotransmitters.
Muscle Cells
Muscle cells allow the movement of the skeleton or contract to squeeze food through the digestive system.
To allow them to do this they have multiple adaptations:
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- Contain mitochondria to transfer the energy needed for contracting.
- Store glycogen, which can be broken down and used in cellular respiration to transfer the energy required for contraction.
Specialised Plant Cells
Root Hair Cell
Root Hair Cells are used to help the plant take up water and dissolved mineral ions.
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To allow them to do this they have multiple adaptations:
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- Root Hair increases the surface area for efficent water uptake.
- Large permanent vacuole to maintain water potential.
- Lots of mitochondria to transfer the energy required for active transport of mineral ions into the cell.
Xylem Cell
Xylem cells make up the xylem tissue which carries water and associated dissolved minerals from the roots up the plant to the leaves. It also provides structure and support to the plant.
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To allow them to do this they have multiple adaptations:
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- Lignin builds up in the cell wall in spiral rings increasing the strength of the xylem allowing them to withstand the water pressure.
- The Xylem cells die forming long hollow tubes that allow water and any dissolved mineral ions to move with little resistance up the plant.
- Pits in the wall allow the horizontal transfer of water from xylem cell to xylem cell.
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Phloem Cell
Phloem cells are specialised to transport the products of photosynthesis around the plant.
To allow them to do this they have multiple adaptations:
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- Cell walls between neighbouring cells breaks down to form sieve plates that allow water to move freely up and down the tubes.
- Phloem cells have relatively few organelles but are kept alive by companion cells. The companion cells contain numerous mitochondria to transfer the energy needed to move dissolved food up and down the plant.
