Key Concepts: Specialised Cells

Specialised cells are designed to perform specific functions within an organism, allowing such organisms to perform complex and diverse tasks.
As a participant in the Biological World, understanding the concept of specialised cells is crucial.
Sperm cells are one of the various examples of specialised cells. They possess a tail (flagellum) that aids movement towards egg cells for fertilisation. They contain very little cytoplasm and lots of mitochondria to release energy needed to swim and fertilise the egg.
Egg cells, also called ovum, are much larger than sperm cells. They carry the food reserves (in the form of a nutrient-rich cytoplasm) to nourish the developing embryo in the early stages after fertilisation.
Nerve cells, also known as neurons, are specialised for rapid signal transmission. They have a long body (axon) to carry the electrical signal from one part of the body to another. Branching dendrites at each end allow the neuron to connect with many other neurons.
Muscle cells are also specialised. They contain a high concentration of mitochondria to release energy needed for contraction. They also contain proteins that slide past each other, causing the muscle to contract or relax.
Root hair cells, found in plants, have a large surface area for water absorption. They do not contain chloroplasts as they are normally underground and hence away from light.
Leaf cells, which perform photosynthesis, are packed with chloroplasts. Their large surface area allows for increased absorption of sunlight.
Phloem cells transport sugar solutions up and down plants. Xylem cells transport water from roots to leaves and provide support to the plant.
Specialised cells differentiate from less specialised cells through the process of cell differentiation. During the development of an organism, cells change in shape and function until they are suited to their specific role.
Cell differentiation happens at different stages of life depending on the organism. For example, in animals, cell differentiation happens at a very early stage whereas, in plants, it can happen throughout life.
Specialised cells group together to form tissues, which can further group to form organs which then group together to form organ systems. Each hierarchy of organisation has specific functions.
Revisit any concept you don’t fully understand until you do. Practise drawing and labelling the different types of specialised cells as this can aid memory recall.