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"Good information about diseases, how they are spread, and also how they are cured."

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Hormones and their effects

Age range 14-16 Age range 16-19

Page 6 of 10

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Insulin

A selection of donuts with multicoloured icing
Eating bread, pasta, donuts or other sugary food causes the glucose level in blood to rise

After eating carbohydrate foods e.g. bread, pasta, sugary foods, the level of glucose in the blood rises. Glucose is important to the cells of the body, particularly the brain, as an energy source. However, the level of glucose in the blood must be regulated so that it does not rise too high.

When the bloodstream contains glucose the pancreas is stimulated to produce the hormone insulin. Insulin causes glucose to be usable by the body cells and excess to be stored in the liver and muscles as glycogen. If the body later needs glucose and none is available in the blood, the liver can convert glycogen back into glucose.

Diabetes

When the amount of insulin is too little (or absent altogether), or the action of insulin in the body is ineffective, the disease diabetes (correctly known as Diabetes Mellitus) will result. It is not a curable disease but can be controlled so that most sufferers can lead a full and normal life. However, if blood sugar levels are not controlled the diabetic could suffer from high blood pressure, and their kidneys, nerves, retina and blood vessels may become damaged.

Type 1 Diabetes

A young woman injects insulin into her thigh
Insulin may have to be injected several times a day

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 quickly in early childhood or adolescence and there are about 350,000 sufferers at present in the UK. A good diet is important but this type of diabetes must be treated with daily injections of insulin. Before the development of insulin as a medicine, type 1 diabetes was usually fatal.

Type 2 Diabetes

An elderly man smiling
Older people, particularly those who are overweight, may suffer from Type 2 diabetes

The kind of diabetes that develops in older people, typically over 40 and overweight, is known as type 2 diabetes. In type 2 diabetes the pancreas does produce insulin but cells become increasingly intolerant to the action of the insulin. There are more than 2 million sufferers of type 2 diabetes in the UK at present and the number seems to be growing. Losing weight and eating a controlled diet can sometimes control type 2 diabetes but, in some cases, oral drugs and injections may be needed.



Genetic Engineering Makes Insulin

At one time, insulin needed for diabetics was extracted from the pancreases of slaughtered pigs, cows and sheep. Nowadays demand for insulin is high and it is important to have a more reliable source. Scientists use a process called genetic engineering to ensure that there is enough insulin for all who need it. 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 some bacterial 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 5


Study the sentences below, then drag and drop
the missing word or phrase to complete the sentence.
insulin
 
 - type of diabetes usually found in children
hormone
 
 - the way large quantities of insulin can be made
pancreas
 
 - the hormone that controls the level of blood glucose
type 1 diabetes
 
 - a chemical messenger
type 2 diabetes
 
 - chromosomes are made of this
injections
 
 - type of diabetes usually found in older people
glucose
 
 - stored in the liver
DNA
 
 - found in the blood after eating sweets
Genetic engineering
 
 - where insulin is made in the body
glycogen
 
 - method of getting insulin into the body

 
Carbohydrate
Energy producing organic compounds which are made of carbon, hydrogen and oxygen. Examples of food containing carbohydrate are rice, pasta, bread and potatoes
Glucose
A type of sugar: a monosaccharide with six carbon atoms (a hexose sugar).
Pancreas
An endocrine gland which produces insulin. Part of the pancreas also produces pancreatic juice which is involved in digestion.
Insulin
A hormone produced by the pancreas. It is active in controlling blood glucose levels.
Liver
A large organ in the upper abdomen which manufactures, stores and breaks down substance as required by the body.
Glycogen
Glycogen is stored in the liver and in muscles and can be converted back to glucose when needed by the body.
Diabetes
A disease in which there is too much sugar in the blood. It results in tiredness, thirst and the production of a large volume of urine.
Adolescent
A young person between childhood and adulthood
Genetic engineering
A general name for the processes which scientists use to produce desired characteristics or substances that are in short supply, such as human growth hormone. Genes are taken from human cells and can be put into bacteria, which reproduce very quickly, and so can produce large quantities of a desired substance.
Chromosomes
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.
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.
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.
Bacteria (singular bacterium)
Unicellular microorganisms of many different types, some of which can cause disease.