Cell differentiation

Animals and plants produced by sexual reproduction begin life as a single cell – a or .

This cell must divide to produce a organism. It must also , so that its cells develop features that enable them to fulfil specific roles.

Examples in animals include:

Cells of the:	Specialised to:
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 to work as a coordinated whole.
Respiratory system	Deliver oxygen for respiration and remove waste carbon dioxide.
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:	Circulatory system
Specialised to:	Transport substances. Defend the body. Regulate temperature.

Cells of the:	Excretory system
Specialised to:	Remove waste products and unwanted substances. Regulate the water content of the body.

Cells of the:	Muscular system
Specialised to:	Bring about movement.

Cells of the:	Nervous system
Specialised to:	Respond to internal and external stimuli and conditions. Carry messages for the body to work as a coordinated whole.

Cells of the:	Respiratory system
Specialised to:	Deliver oxygen for respiration and remove waste carbon dioxide.

Cells of the:	Reproductive system
Specialised to:	Bring about fertilisation to produce new offspring.

Cells of the:	Skeletal system
Specialised to:	Bring about movement. Support and protect internal structures. Produce blood cells. Store and release calcium.

Some specialised cells of plants:

Cells of the:		Specialised to:
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 photosynthesis.
	Guard cells	Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen.
Phloem	Sieve tubes	Transport products of photosynthesis, including sugars and amino acids, 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 by mitosis.

Cells of the:
	Spongy mesophyll
Specialised to:	Allow gases to circulate for the exchange of gases between the leaf and the environment. Carry out photosynthesis.

Cells of the:
	Guard cells
Specialised to:	Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen.

Cells of the:	Phloem
	Sieve tubes
Specialised to:	Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed.

Cells of the:
	Companion cells
Specialised to:	Provide the energy required for transporting substances in sieve tubes.

Cells of the:	Xylem
	Xylem vessels
Specialised to:	Transport water and dissolved minerals from the roots, up the plant.

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