Genetic diseases

Diseases caused by a fault in a person's DNA

Cystic fibrosis is a genetic disease It is the result of just one change in a protein

Just one difference in the base sequence in a length of DNA (a gene) will cause a change in the nature of the protein encoded by the gene

"CFTR" is a protein found in the plasma membrane (plasma-membrane protein) CFTR is the protein responsible for the active transport of chloride ions out of the cell

Its tertiary protein structure is altered because the primary structure contained a base change As a result of the change in tertiary structure, the protein cannot carry out its function of actively transporting chloride ions out of the cell

People with such a faulty protein are unable to maintain the correct water potential of the mucus found in the respiratory tract A thicker mucus is the result with, as a consequence, lungs that become blocked

Severe and chronic breathing problems occur as well as a tendancy to lung infection due to the build up of thick mucus

Digestion is also affected by the thick mucus

The gut cannot absorb foodstuffs so readily & sufferers of Cystic Fibrosis must take enzyme capsules to aid their digestion

To be able to explain the problems caused by this disease, you need to have an understanding of the role of *ribosomes, *endoplasmic reticulum *the Golgi body (or apparatus) *vesicles in the production of the CFTR protein & mucus.

You may like to try http://www.cftrust.org.uk/ or http://www.sciencemuseum.org.uk/exhibitions/genes/234.asp for further information