Sperm cell

The main function of the sperm cell is to carry genetic information to the egg cell. When the nuclei of the male and female sex cells fuse this is called fertilisation.

Sperm can be found inside the testes – the male sex organs.

The sperm cell has a number of adaptations that make it able to carry out its job:

The head contains the nucleus which holds the genetic information to be passed onto it’s offspring. The head also contains an enzyme to help penetrate the egg cell membrane.

The middle section is packed with mitochondria to supply energy for the sperm cell to swim.

The tail helps the sperm cell to swim towards the egg.

ESDGC Interesting fact:Drosophila bifurca, is a tiny fruit fly whose coiled sperm would measure more than 6 centimetres (2.4 inches) long if straightened out. That is 20 times the size of the fruit fly itself and 1,000 times longer than an average human sperm!

Egg Cell

The main function of the egg cell is to carry genetic information. When the nuclei of the male and female sex cells fuse this is called fertilisation. The scientific name for an egg cell is an ovum (or ova pleural).

Ova can be found inside the ovaries – the female sex organs.

Ova are much larger than sperm cells.

The ovum cell has a number of adaptations that make it able to carry out its job:

The nucleus holds the genetic information to be passed onto it’s offspring. The cytoplasm contains yolk which provides nutrients for the embryo (growing baby) if fertilised. The ‘jelly coat’ makes sure only one sperm cell can fertilise the egg

ESDGC Interesting fact:The largest baby born so far in 2017 was in New Zealand and weighed a whopping 16lb and 4oz. That is as heavy as 3 bags of sugar!

Plant leaf palisade cell

The main function of the palisade cell is to absorb sunlight so the plant can carry out photosynthesis and produce sugars needed for growth.

Carbon dioxide + water light energy glucose + oxygen chlorophyll

Palisade cells can be found on the upper surface of the plant’s leaves. They are located here because the upper surface is where the sunlight falls. The palisade cell has a number of adaptations that make it able to carry out its job:

Palisade cells are packed with chloroplasts that contain a green pigment called chlorophyll. Chlorophyll absorbs the sunlight energy needed to power the process of photosynthesis.The chloroplasts can actually move inside the palisade cell to absorb the most sunlight possible.

The cell shape is tall and narrow so that lots of cells can fit closely together. This increases the surface area over which photosynthesis can occur.

ESDGC Interesting fact:The World’s tallest trees are called Redwoods (Seqoia sempervirens) and are found in California.

Nerve cells – Neurones

Cell body

The main function of the neurone cell is to carry electrical messages to different parts of the body.Neurones connect the sense receptors to the central nervous system and also connect one part of the nervous system to another, for example in the brain and spine. They also carry signals from the nervous system to effector organs, such as muscles and glands.When neurons are stimulated they transmit an electrical impulse.

Neurones are found in the nervous system.

The neurone has a number of adaptations that make it able to carry out its job: Neurones are very long so they have a very large surface area to carry messages around the body.The neurone has a nucleus surrounded by cytoplasm. The cytoplasm forms extensions around the nucleus called dendrites. Dendrites bring electrical impulses to the cell body. The cytoplasm also forms a long fibre called an axon that is surrounded by a cell membrane. The axon carries the electrical impulses away from the cell body and is protected by a fatty sheath - a bit like the plastic coating around an electrical wire. The fatty sheath increases the speed at which the nerve impulse is transmitted. The nerve ending is branched to make good contact with other neurons or the effector organ.

Two neurones do not make direct contact. Where they meet, there is a very small gap called a synapse. The signal needs to cross this gap to continue on its journey to, or from, the central Nervous System. This cannot be in the fomr of an electrical message, instead it is done by means of chemicals which diffuse across the gap between the two neurones.

ESDGC Interesting fact:To study the structure and function of neurones Scientists used the Giant Squid. The Giant Squid is found in Newfoundland, Norway. Its cell body diameter is 1mm and its axon is up to 1m in length!

Ciliated epithelial cell

Ciliated epithelial cells can be found in the trachea (windpipe) and in the small intestine.

The surface of these cells are covered with tiny, microscopic hair-like structures called cilia. Cilia wave from side-to-side, brushing dirt and microbes from our lungs.

ESDGC Interesting fact:When you smoke the cilia in your trachea become paralysed for one hour. This results in the poisonous chemicals in the tobacco smoke reaching your lungs and can cause severe damage and lung cancer. The country with the largest number of cases of lung cancer is Hungary.

Lymphocyte cell

A lymphocyte is a type of white blood cell.

The main function of the lymphocyte cell is to fight infections by releasing antibodies that destroy disease-causing microorganisms.

Lymphocytes can be found in the spleen, tonsils and lymph nodes. The lymphocyte cell has a number of adaptations that make it able to carry out its job:

Lymphocytes have an irregular shape so that they can squeeze out of blood vessels and get to the site of infection.

Lymphocyte cells have a very large nucleus to allow it to produce antibodies.

ESDGC Interesting fact:When you get an infection your lymph nodes produce a lot of lymphocytes. Lymphocytes produce antibodies to try to fight the infection.Some cancer treatments use antibodies to help fight cancer. Denmark has the highest number of recorded cancer cases.

Red blood cells

A red blood cell is a type of white blood cell.

The main function of the red blood cell is to carry oxygen from the lungs to other parts of the body.

Red blood cells are found in the bloodstream.

The red blood cell has a number of adaptations that make it able to carry out its job:

Red blood cells are bi-concave in shape. This means they dip in on both sides a bit like a doughnut. This gives them a large surface area to pick up oxygen.

Their cell membrane is flexible so they can squeeze through the blood vessels and travel around the body.

The cytoplasm of the red blood cells contain a pigment called haemoglobin. Haemoglobin binds to oxygen and allows the red blood cell to carry it around the body.

Red blood cells do NOT have a nucleus. This gives them more space inside to hold more haemoglobin pigment and carry more oxygen. However, having no nucleus mean the cells have a short life of 120 days.

ESDGC Interesting fact:Scientists have shown that athletes produce more red blood cells to increase oxygen delivery to the working muscles.Usain Bolt holds the record for the fastest 100m sprint. He comes from Jamaica.

Muscle cells

The main function of the muscle cell is to contract to bring about movement.

Muscle cells have a cell membrane, nucleus and cytoplasm like other cells.

The muscle cell has a number of adaptations that make it able to carry out its job:

The muscle cells are elongated. They contain protein fibres that can contract when energy is available, to shorten and lengthen the cell. When you contract your biceps all of the cells in the muscle have shortened.

ESDGC Interesting fact:The 2017 winner of the the well-known competition ‘The World’s Strongest Man’ comes from Botswana. He has trained very hard and developed very strong muscles.

Virus cell

Viruses are pathogenic microorganisms. This means that they are microscopic cells that cause diseases. They are parasitic cells and can only survive inside a living cell.

The main function of the virus cell is to invade a host organism and take over its cells for their own benefit. They then instruct the host’s cells to make copies of the virus. When it has made enough copies of the virus the host cell bursts, releasing the virus cells into the host organism. These new virus cells then invade even more host cells spreading the infection or disease.

Viruses are often considered to be non-living as they cannot survive without a living host cell.

The virus has a number of adaptations that make it able to carry out its job:

It doesn’t have a nucleus. Instead it just has a strand of genetic material (DNA or RNA) which is surrounded by a protective protein coat (the capsid). They may also have a tail section.

ESDGC Interesting fact:South Africa has the highest HIV epidemic. This condition is caused by the Human Immunodeficiency Virus (HIV) shown above.

Fat Cells

Adipocyte is the scientific term for a fat cell. Fat cells are found throughout the human body between the skin and muscle areas. They can also be found surrounding the organs inside of the body.

Fat cells act as food reserves and help to insulate, and are made when energy intake exceeds energy use.

The fat cell has a number of adaptations that make it able to carry out its job: They are very large cells but only have a small amount of cytoplasm, making a lot more room for fat stores. They can expand by up to 1000 times their normal size.

They are expandable because they have a loose membrane and cytoskeleton which support cell expansion as it fills up with fat. There are also relatively few mitochondria and ribosomes as they do not need many proteins or much energy as normal cells.

ESDGC Interesting fact:The World’s most obese country is Egypt.You can also find many camels in the Egyptian desert. A camel's hump stores fat, which it uses as source of nourishment when food is scarce.