Absorption – process by which nutrient substances are taken in and processed by the small intestine before being moved into the blood stream to be used around your body.
ALT – alanine aminotransferase, a liver enzyme that enters the blood following liver damage. An increase in ALT levels, as measured in liver function tests, may indicate the presence of liver disease.
Amino acids – the compounds that make up proteins. Proteins in the human body are made of 20 different amino acids that are either manufactured by the body or absorbed from your diet.
Anaemia – a condition in which you have less than the normal amount of red blood cells or haemoglobin in your blood.
AST – aspartate aminotransferase, a liver enzyme but less specific to the liver than ALT (see above). A raised AST level may follow a heart attack, for example.
Base sequence – the order of the chemical units known as ‘nucleotide bases’ (adenine, thymine, cytosine and guanine) in DNA that forms the genetic code. The sequence of the bases will determine what protein is produced.
Cell – the most basic and smallest functioning unit or ‘building block’ of living things. Your body is made up of cells, each with its own unique functions and features. Within the outer skin (membrane) of each cell is a central compartment known as the cell ‘nucleus’ that contains your genetic material.
Chromosome – a single, long molecule of DNA that holds our genes, contained within the nucleus of a cell. A cell should contain 46 chromosomes in two pairs of 23. One set of 23 chromosomes is inherited from the egg of the biological mother and the other from the sperm of the biological father. Chromosomes are numbered from 1 to 22 (and known as ‘autosomes’) with the 23rd pair, the sex chromosomes, designated ‘X’ and ‘Y’.
DNA – deoxyribonucleic acid, the chemical compound of which chromosomes are made and which contains the genetic instructions for the making of proteins in your body. DNA molecules
consist of two paired strands that twist to form a double helix. Each strand is made of four chemical units called ‘nucleotide bases’. These are adenine (A), thymine (T), guanine (G), and cytosine (C). They pair specifically with bases on opposite strands e.g. ‘A’ always with ‘T’, ‘C’ always with ‘G’ etc. and their order determines the meaning of the information encoded in that part of the DNA molecule.
Enzyme – a protein that speeds up a chemical reaction within a cell, without being changed or used up in the reaction.
Expression – the process where information encoded in a gene is converted into the structures
and functions of a cell.
Ferritin – the protein that stores iron in your body. As the amount of iron increases, so do the levels of ferritin in the serum. Measuring ferritin levels is more accurate than measuring blood iron in the long run, as the latter may vary with diet.
Free radical – an unstable molecule created from the metabolism of oxygen in your body. Free radicals belong to a group known as ‘reactive oxygen species’. Although a by-product of normal cell function, when too many are generated they can become toxic and lead to cell damage.
Gene – a segment of a chromosome (or unit of DNA) that carries the instructions or code for making a specific protein or set of proteins responsible for, or contributing to, a specific physical trait or action.
Genotype – the genetic makeup encoded in your DNA.
Haemoglobin – an iron-containing protein (metalloprotein) contained in the red blood cells. Haemoglobin is responsible for transporting oxygen from the lungs to the rest of your body. It is also the pigment that provides the colour of red blood cells.
Hepatocyte – a liver cell.
Inflammation – the first response of the immune system to infection, commonly characterised by heat, swelling, pain and tenderness.
Molecule – the smallest component of a substance able to show the typical chemical properties of that substance. Molecules are made up of atoms that are held together by chemical bonds and make up all living and non-living things.
Mutation – an occurrence where a gene undergoes a change or variation in the base sequence of its DNA. Some mutations result in the gene no longer coding for the correct protein, or producing a reduced amount of the protein.
Nutrient – a substance required from our diet for growth and sustenance of life. Nutrients can be ‘organic’, such as carbohydrates, fats, proteins and vitamins, or ‘inorganic’. Inorganic nutrients are usually minerals such as water, oxygen or iron.
Oxygen – an odourless, colourless gas absorbed from the atmosphere through your lungs and into your blood. Oxygen is a major component of organic molecules and is necessary for most forms of life.
Peptide – a compound formed when two or more amino acids are joined.
Protein – the active molecule in cells that determines the physical structure of the organs and tissue that make up your body. Proteins also control the biological and chemical reactions within your body.
Serum – more than half of your blood is made of plasma, the substance which carries the circulating blood cells and platelets. Normally clear or yellowish, serum is the liquid that separates from blood when clotting occurs. Many chemical tests will carried out using serum.
Transferrin – a protein that binds iron in the blood serum and carries it around your body. The
percentage of transferin bound to iron is increased in haemochromatosis.
Variant – as in gene variant, a term that may be used in place of ‘mutation’ (see above) as many gene changes do not cause any disorder.