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Genetic engineering

Genetic engineering involves changing the DNA of an organism, usually by deleting, inserting or editing a gene to produce desired characteristics.

Restriction enzyme

Enzymes produced by certain bacteria which cut DNA at specific sites. They are widely used in genetic engineering.

Type 1 diabetes

Develops when the body does not produce the right amount of insulin or, in some cases, does not produce any at all. It must be treated with daily injections of insulin. People affected also need to manage their diet, eat regularly and plan exercise carefully to balance their energy needs with their food and insulin intake.

Type 2 diabetes

The pancreas does produce insulin but cells stop responding properly to the insulin. It is often linked to obesity and lack of exercise and taking more exercise, losing weight and eating a carefully balanced diet can often control or even reverse type 2 diabetes.

Balanced diet

A diet which contains the correct amounts of carbohydrates, proteins, lipids, vitamins, minerals and fibre to provide your cells with the resources they need.

Chromosome

A chromosome is like a packet of coiled up DNA. Humans have 23 pairs of chromosomes. They are in the nucleus of every human cell.

Bacteria

Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus

Diabetes mellitus

A disease resulting from a lack of insulin production by the pancreas or a loss of the cell response to insulin that causes a loss of control of the glucose balance of the body.

Plasmid

A small circle of extra DNA found in bacteria

Obesity

A disorder where an excessive amount of fat has accumulated in the body. It results when the energy taken in as food is stored in the body instead of being used up through activity

Gene

A short piece of DNA which is responsible for the inheritance of a particular characteristic. It codes for the production of a specific protein. Genes occupy a fixed position, called a locus, on a particular DNA molecule.

DNA

Deoxyribonucleic acid. This is the molecule which contains the genetic code. It coils up tightly inside chromosomes. DNA is a double helix made from two strands which are joined together by pairs of bases.

Type 1 and type 2 diabetes

Some people cannot control their blood sugar level within the normal body limits. This can cause all sorts of problems for the body - but fortunately there are medicines that can help.

Type 1 diabetes

Type 1 diabetes develops when the body does not produce the right amount of insulin or, in some cases, does not produce any at all. It usually develops fairly early in childhood or adolescence and there are around 300,000 sufferers at present in the UK. This type of diabetes must be treated with daily injections of insulin. People affected also need to manage their diet, eat regularly and plan exercise carefully to balance their energy needs with their food and insulin intake. Before the development of insulin as a medicine, type 1 diabetes was usually fatal. Now it can be well managed and controlled.

Injecting insuling

People with type 1 diabetes have to monitor their blood sugar levels and inject insulin several times a day.

Type 2 diabetes

Type 2 diabetes usually develops in older people, often over 40 and overweight. In type 2 diabetes the pancreas does produce insulin but cells stop responding properly to the insulin. There are almost 3 million sufferers of type 2 diabetes in the UK at present and the number is growing. Type 2 diabetes is often linked to obesity and lack of exercise and taking more exercise, losing weight and eating a carefully balanced diet can often control or even reverse type 2 diabetes. However for some people oral drugs and even injections of insulin may be needed.

People

As the numbers of overweight people in the population increase, the number of relatively young people developing type 2 diabetes is also going up.

You can learn more about diabetes in the Diabetes topic resource.

Genetic engineering makes insulin

At one time, insulin needed for diabetics was extracted from the pancreases of slaughtered pigs (and sometimes cows). The amount of insulin available for treating people with diabetes varied with the number of animals slaughtered for meat. It was not exactly the same as human insulin either, which caused problems for some people.

In recent years the number of people with diabetes has risen. However scientists used a process called genetic engineering to make sure there is enough insulin for everyone who needs it. Now diabetes is treated using human insulin made not by humans but by bacteria! The insulin produced by genetic engineering is identical to human insulin which is an added advantage of this process.

  • Researchers found the part of a human chromosome that has the gene for making insulin.
  • They carefully cut out the gene using a restriction enzyme and put it into a bacterial plasmid (a small circle of DNA).
  • This DNA was put into a new bacterium.
  • The bacterium grew and multiplied to produce very large numbers of bacteria each with the insulin-making gene inside.
  • The large numbers of bacteria could make a large amount of insulin.

Question 2