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. We will be looking into this more closely below:
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 break down the outer membrane of the egg cell, and then penetrate the egg cell. Once it penetrates the egg, the genetic material in the haploid sperm cell can combine with the genetic material of the haploid egg cell. This is known as fertilisation. Eggciting stuff!
The sperm cell is also suited to its job by having a tail to allow it to swim towards the egg. It uses the energy provided by the mitochondria to power the tail.
NERVE CELL/NEURONE - One of its features is a structure that looks like a tail, called the axon. This can be really long! The axon allows nerve impulses to travel all across the body at lightning fast speed, and for nerve impulses to be passed along to other cells. It's covered in a blanket of fatty cells called the myelin sheath. This helps to protect the nerve cell from damage and helps speed up the transmission of nerve impulses.
Nerve cells also contain dendrons. Dendrons are branches (that further divide into dendrites) which receive nerve impulses from other nerve cells.
MUSCLE CELLS - These are made up of protein filaments and 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. We have control over our skeletal muscles. Cardiac muscle cells, which make up the heart, contract rhythmically, allowing the heart to pump blood around the body. These muscles contract automatically. Smooth muscle cells are usually found lining our organs and can help with contracting, for example, your bladder. Smooth muscles also contract automatically. Muscles contain mitochondria, allowing energy from respiration for muscle contraction.
What about plants? Yes, plants have specialised cells too!
ROOT HAIR CELLS - are tiny projections on the actual roots of the plant. They give the roots a bigger surface area, which allows more water to be in contact with the root hair cell and means more water can be absorbed. The thin walls of the roots mean that water and nutrients can pass into the plant very quickly.
XYLEM AND PHLOEM CELLS - Xylem cells transport water in one direction (from the root to the leaves) and are made of a thick hardened non-living structure called lignin (in trees this is the woody part). 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 (this is called translocation). 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 apply and demonstrate your knowledge of the different specialised cells and how their adaptations help them to carry out their job.