Cell differentiation
Animals and plants produced by sexual reproduction begin life as a single cell - a fertilisationThe joining of a male and female gamete. egg cellThe female reproductive cell. or zygoteA fertilised egg cell..
This cell must divide to produce a multicellularHaving more than one cell. organism. It must also differentiationWhen an unspecialised cell becomes a more specialised cell type., so that its cells develop features that enable them to fulfil specific roles.
Examples in animals include:
| Cells of the鈥 | Specialised to鈥 |
| Circulatory system | Transport substances, defend the body, regulate temperature |
| Excretory system | Remove waste products and unwanted substances, regulate the water content of the body |
| Muscular system | Bring about movement |
| Nervous system | Respond to internal and external stimuli and conditions, carry messages for the body, work as a coordinated whole |
| Respiratory system | Deliver oxygen for respiration and remove waste |
| Reproductive system | Bring about fertilisation to produce new offspring |
| Skeletal system | Bring about movement, support and protect internal structures, produce blood cells, store and release calcium |
| Cells of the鈥 | Circulatory system |
|---|---|
| Specialised to鈥 | Transport substances, defend the body, regulate temperature |
| Cells of the鈥 | Excretory system |
|---|---|
| Specialised to鈥 | Remove waste products and unwanted substances, regulate the water content of the body |
| Cells of the鈥 | Muscular system |
|---|---|
| Specialised to鈥 | Bring about movement |
| Cells of the鈥 | Nervous system |
|---|---|
| Specialised to鈥 | Respond to internal and external stimuli and conditions, carry messages for the body, work as a coordinated whole |
| Cells of the鈥 | Respiratory system |
|---|---|
| Specialised to鈥 | Deliver oxygen for respiration and remove waste |
| Cells of the鈥 | Reproductive system |
|---|---|
| Specialised to鈥 | Bring about fertilisation to produce new offspring |
| Cells of the鈥 | Skeletal system |
|---|---|
| Specialised to鈥 | Bring about movement, support and protect internal structures, produce blood cells, store and release calcium |
Some specialised cells of plants:
| Cells of the鈥 | Specialised to鈥 | |
| Leaf | Palisade mesophyll | Carry out photosynthesis |
| Spongy mesophyll | Allow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis | |
| Guard cells | Open and close to control the exchange of gases 鈥 carbon dioxide, water vapour and oxygen | |
| Phloem | Sieve tubes | Transport sugars produced in photosynthesis from the leaf to where they are needed |
| Companion cells | Provide the energy required for transporting substances in sieve tubes | |
| Xylem | Xylem vessels | Transport water and dissolved minerals from the roots, up the plant |
| Growing points | Meristem | Produce new cells as they divide |
| Cells of the鈥 | Leaf |
|---|---|
| Palisade mesophyll | |
| Specialised to鈥 | Carry out photosynthesis |
| Cells of the鈥 | |
|---|---|
| Spongy mesophyll | |
| Specialised to鈥 | Allow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis |
| Cells of the鈥 | |
|---|---|
| Guard cells | |
| Specialised to鈥 | Open and close to control the exchange of gases 鈥 carbon dioxide, water vapour and oxygen |
| Cells of the鈥 | Phloem |
|---|---|
| Sieve tubes | |
| Specialised to鈥 | Transport sugars produced in photosynthesis from the leaf to where they are needed |
| Cells of the鈥 | |
|---|---|
| Companion cells | |
| Specialised to鈥 | Provide the energy required for transporting substances in sieve tubes |
| Cells of the鈥 | Xylem |
|---|---|
| Xylem vessels | |
| Specialised to鈥 | Transport water and dissolved minerals from the roots, up the plant |
| Cells of the鈥 | Growing points |
|---|---|
| Meristem | |
| Specialised to鈥 | Produce new cells as they divide |