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ARTICLE

The body’s first line of defence

Your body has a two-line defence system against pathogens (germs) that make you sick. Pathogens include bacteria, viruses, toxins, parasites and fungi. The first line of defence (or outside ...

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Bacterial DNA – the role of plasmids

Like other organisms, bacteria use double-stranded DNA as their genetic material. However, bacteria organise their DNA differently to more complex organisms. Bacterial DNA – a circular chromosome ...

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Meiosis, inheritance and variation

Although we are all unique, there are often obvious similarities within families. Maybe you have the same nose as your brother or red hair like your mother? Family similarities occur because we ...

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The body’s second line of defence

If the pathogens are able to get past the first line of defence, for example, through a cut in your skin, and an infection develops, the second line of defence becomes active. Through a sequence ...

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Role of proteins in the body

Proteins are molecules made of amino acids. They are coded for by our genes and form the basis of living tissues. They also play a central role in biological processes. For example, proteins ...

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What levers does your body use?

Muscles and bones act together to form levers. A lever is a rigid rod (usually a length of bone) that turns about a pivot (usually a joint). Levers can be used so that a small force can move a ...

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Cell organelles

Every cell in your body contains organelles (structures that have specific functions). Just like organs in the body, each organelle contributes in its own way to helping the cell function well as ...

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Energy for exercise

Why is a muscle like a motor bike? Although muscles and engines work in different ways, they both convert chemical energy into energy of motion. A motorbike engine uses the stored energy of ...

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Bacteria – good, bad and ugly

Bacteria range from the essential and useful, to the harmful. Essential bacteria Without the key functions of some bacteria, life on earth would be very different: Some bacteria degrade organic ...

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Genotype and phenotype

We are all unique. Even monozygotic twins, who are genetically identical, always have some variation in the way they look and act. This uniqueness is a result of the interaction between our ...

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Bacterial transformation

Bacteria are commonly used as host cells for making copies of DNA in the lab because they are easy to grow in large numbers. Their cellular machinery naturally carries out DNA replication and ...

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DNA extraction

DNA extraction is a routine procedure used to isolate DNA from the nucleus of cells. Scientists can buy ready-to-use DNA extraction kits. These kits help extract DNA from particular cell types or ...

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DNA cloning

DNA cloning is the starting point for many genetic engineering approaches to biotechnology research. Large amounts of DNA are needed for genetic engineering. Multiple copies of a piece of DNA can ...

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DNA profiling

DNA profiling is the process where a specific DNA pattern, called a profile, is obtained from a person or sample of bodily tissue Even though we are all unique, most of our DNA is actually ...

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Muscle structure - muscle under the microscope

Does all muscle look the same? If you were to look at skeletal, smooth and cardiac muscle using a microscope, you would see differences in their structure. Skeletal muscle Skeletal muscle looks ...

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Mitochondria – cell powerhouses

Mitochondria are tiny organelles inside cells that are involved in releasing energy from food. This process is known as cellular respiration. It is for this reason that mitochondria are often ...

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E. coli – the biotech bacterium

The bacterium Escherichia coli (E. coli for short) is crucial in modern biotechnology. Scientists use it to store DNA sequences from other organisms, to produce proteins and to test protein ...

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Preparing samples for the electron microscope

Electron microscopes are very powerful tools for visualising biological samples. They enable scientists to view cells, tissues and small organisms in very great detail. However, these biological ...

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Impacts of biotechnology on society

Biotechnology has helped improve the quality of people’s lives for over 10,000 years. Today’s biotechnologies vary in application and complexity. However, they all have potential to change our ...

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Large intestine function

Recent research has revealed that the large intestine and its resident bacterial population have key roles to play in determining our health and wellbeing. It is much more than just a waste ...

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How to add foreign DNA to bacteria

Using modern laboratory techniques, it is relatively easy to add pieces of foreign DNA to bacteria. To do this, scientists first package their DNA of interest within a circular DNA molecule (a ...

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How microscopes magnify

A microscope is something that uses a lens or lenses to make small objects look bigger and to show more detail. This means that a magnifying glass can count as a microscope! It also means that ...

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