Glossary
Amino Acid
Amino acids are the basic building blocks of proteins. The type and order of amino acids which join together to make a protein are determined by DNA in the cell that produces the protein, and will affect the structure and function of the protein in the body.
Antagonist
An antagonist blocks or reduces a biological action for example by preventing a substance binding to its receptor and starting a reaction.
Antioxidant
Antioxidants slow or prevent oxidative damage to cells. Oxidation is a chemical reaction that produces free radicals, which start chain reactions that damage cells. Antioxidants such as vitamin e terminate these chain reactions by reacting with the free radicals themselves and removing them from the chain.
Ataxia Telangiectasia (AT)
A rare childhood neurological disorder. Affected children show impaired coordination and balance (ataxia) and may also have a weakened immune system, frequently suffering from infections. A high number of affected children also develop cancers such as leukaemia or lymphoma. Telangiectasia are small, red veins which may appear on the surface of the ears and cheeks or in the corners of the eyes in patients. There is currently no cure. More information on AT can be found on the A-T society homepage at www.atsociety.org.uk
Brown fat
Brown fat is one of the two types of fat tissue (the other being white fat tissue) that is present in many newborn or hibernating mammals. Its primary purpose is to generate body heat and it is rich in mitochondria, the energy producing units of cells.
Cerebellar Ataxia
Cerebellar ataxia is a disorder of the nervous system which affects balance and coordination.
Differentiation
Cellular differentiation is the process by which a less specialised cell from a fertilised egg becomes a more specialised cell type such as a nerve cell or muscle cell. Differentiation also occurs in adults during tissue repair and normal cell turnover.
DNA
DNA is a molecular structure containing the instructions for all components and processes which make up living organisms. A DNA strand is made up of repeating units called nucleotides, linked to a backbone made of sugar and phosphate. The four different nucleotides are: adenine, cytosine, guanine, thymine, often represented by their first letters: A, C, G and T.
Enzyme
Enzymes are biological molecules that catalyze (i.e. increase the rates of) chemical reactions. Many medicines and poisons are enzyme inhibitors, decreasing the activity of enzymes and slowing or preventing chemical reactions in the body.
Frataxin
Frataxin is a small protein, found in the mitochondria. Its function is not entirely clear, but it seems to be involved in assembly of iron-sulphur clusters and maintaining appropriate iron levels in the mitochondria.
Free Radical
In general a free radical is any molecule that has a single unpaired electron in an outer shell. Since electrons like to exist in pairs, this makes free radical molecules very eager to react with other molecules in order to become more stable. This reaction often results in damage to larger molecules within cells, known as oxidative damage or oxidative stress.
Haeme
Haeme is the iron-containing component of haemaglobin, which carries oxygen in the blood.
Heterochromatin
A tightly packed form of DNA. It may control the expression of certain genes through regulation of transcription initiation.
Histone Deacetylase inhibitors
During transcription of genes, DNA is coiled and uncoiled around a histone backbone, with the help of molecules called histone acetylases which add acetyl groups to make an open, active structure which can be read, and Histone deacetylases (HDAC) which removes these acetyl groups, making the chromatin structure dense and unreadable. HDAC inhibitors are a class of compounds that interfere with the removal of acetyl groups from the DNA structure, thus making it open and readable again. HDAC inhibitors have a history of use in psychiatry and neurology as mood stablilisers and anti-epileptics, for example, the drug valproic acid. More recently, HDAC inhibitors are being studied as a potential therapy for neurodegenerative diseases.
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is a heart condition associated with Friedreich’s ataxia. The heart muscle becomes thickened and can obstruct the flow of blood. The severity and symptoms this causes range from mild to severe. Some people need no treatment. Others require medication, surgery or other treatments.
Intron
Introns are sections of DNA which interrupt genes and do not contain information specifying a particular protein.
MRI scan
MRI (Magnetic resonance imaging) scans are used in medical imaging to give clear pictures of structures inside the body, such as the brain and spine. It uses magnets instead of radiation as used in other scanning methods such as CT scanning.
MRS
MRS (Magnetic resonance spectroscopy) is another type of imaging used in medicine, which gives information about the dynamics of a structure, such as changes in temperature, activity and metabolism. It is mainly used to study the brain growth and disorders, and metabolic conditions of muscles and nerves.
Mitochondria
Mitochondria are organelles in each cell which use oxygen and nutrients to create energy. They are sometime called the ‘powerhouses’ or ‘batteries’ of cells and are found in varying numbers in all cells, depending on the energy requirements of the cell. In addition to supplying cellular energy, mitochondria are involved in a range of other processes, such as cell growth and cell death. Mitochondria have been implicated in several human diseases and may play a role in the aging process.
Oxidative stress
Oxidative stress is caused by an imbalance between the production of toxic free radicals and the body’s ability to detoxify or easily repair the resulting damage. An example of oxidation damage occurs when iron is exposed to oxygen and rust forms. In humans, oxidative stress is involved in many diseases, such as atherosclerosis, Parkinson’s disease and Alzheimer’s disease, as well as different types of ataxia.
Pancreas
The pancreas is a body organ with roles in the digestive and endocrine (hormone) systems. It secretes enzymes to aid digestion and produces insulin to control blood sugar. Impaired function of the pancreas leads to diabetes.
Phenotype
A phenotype is the qualities of an organism which can be seen such as appearance (e.g. blue eyes) or behavior, as opposed to its genotype - the inherited instructions in its DNA.
Placebo
An inactive pill, liquid or other substance with no medical value used in clinical trials as a control to compare against an experimental treatment.
RNA
A molecule similar to DNA which is made from the DNA template during protein synthesis. There are different types of RNA, for example messenger RNA (mRNA) which carries coding information from DNA to the sites of protein synthesis. (See Transcription)
Sensory nerve
Sensory nerves receive information from parts of the body, such as how something feels and if it is painful. They are made up of nerve fibers which relay this information to the central nervous system (spinal cord and brain).
Skeletal muscle
Skeletal muscle is a type of muscle attached to the skeleton. Contraction of different skeletal muscles applies force to bones and joints to create movement.
Spinocerebellar degeneration
Spinocerebellar degeneration and cerebellar degeneration describe changes that have taken place in a person’s nervous system. Cerebellar and spinocerebellar degeneration have many different causes.
Stem cells
Stem cells are unspecialised cells that have not yet differentiated into any specific type. They are unique because they can reproduce themselves infinitely. They can also generate more specialised cell types, such as muscle, nerve or bone cells.
Transcription
Transcription is the production of RNA following the instructions contained in DNA. Both DNA and RNA sequences use the same language, and the information is simply transcribed, or copied, from one molecule to the other. DNA sequence is copied to produce a complementary nucleotide RNA strand, called messenger RNA (mRNA), which carries the genetic message from the DNA to the protein-synthesizing machinery of the cell.
Trinucleotide
Nucleotides in sets of threes are called trinucelotides or codons and carry the genetic code for a specific amino acid.
