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Living things or organisms are made up of cells. Some organisms may be made up of just a single cell (unicellular), like bacteria, whereas others are made up of many cells, like a plant.
Some cells have particular jobs they need to carry out and are called specialised cells. Read below to learn about some of the most common specialised cells found in the body and in plants:
THE SPERM CELL - The job or function of the sperm cell is to fertilise an egg cell. The head of the sperm cell, called the acrosome, contains enzymes which help the sperm cell to penetrate the egg cell. Once it penetrates the egg, the genetic material in the sperm cell can combine with the genetic material of the egg cell. This is known as fertilisation. Eggciting stuff!
Another clever feature of the sperm cell is the long tail. This allows it to swim towards the egg. It uses the energy provided by the mitochondria to power the tail.
THE NERVE CELL - The nerve cell also looks like it has a tail. This structure is called the axon, which can be really long. This allows nerve impulses to travel all across the body at lightning fast speed. The axon also allows nerve impulses to be passed along to other cells, like muscles. It's covered in a blanket of fatty cells called the myelin sheath, which helps to protect the nerve cell from damage and speed up the transmission of nerve impulses.
MUSCLE CELLS - These are arranged in bundles, which means that the muscle can contract or shorten. There are three main types: skeletal, cardiac and smooth. Skeletal muscles are connected to our bones, which allows us to move. Cardiac muscle cells found in the heart contract rhythmically, allowing the heart to pump blood around the body. Smooth muscle cells are usually found lining our organs and can help with contracting different organs - your bladder, for example. Muscles contain mitochondria, allowing energy for muscle contraction to happen.
What about plants? Yes, plants have specialised cells too!
ROOT HAIR CELLS - these are tiny projections on the actual roots of the plant. They give the roots a bigger surface area, which means more water can be absorbed. The thin walls of the roots enable water and nutrients to pass into the plant super quick.
XYLEM AND PHLOEM CELL - Xylem cells transport water in one direction (from the root to the leaves) and are made of a thick hardened structure called lignin. The lignin helps to keep the plant upright and supported. Phloem cells transport glucose and other substances, like amino acids, up and down the plant to where they are needed. The mitochondria in the companion cells next to the phloem cells provide the energy needed for the movement of substances around the plant.
In the following activity, you will be asked to describe the different specialised cells and how their adaptation helps them to carry out their job.
