Allele: One of a pair of genes that occupy the same site on a chromosome. All genes come in pairs: you inherit one allele of each gene from your mother and one from your father.
Antibody: Antibodies are the soldiers of the immune system; they move freely in the blood, seeking out invaders such as bacteria and viruses and flagging them up for destruction. Antibodies are tailor-made by the immune system to recognise and attach to specific targets, which makes them excellent tools for ‘finding’ target molecules in researchers’ laboratory experiments.
Apoptosis: Programmed cell death, or cell suicide.
Bacteriophage: A virus which targets and infects bacteria.
Carcinogen: A substance capable of causing cancer.
Carcinoma: A type of cancer that starts in the epithelial cells that form the outer membranes of all the organs, tubes and cavities in our bodies, and include our skin. At least 80 per cent of cancers are carcinomas (see also sarcoma, leukaemia, lymphoma).
Cell culture: A laboratory process in which cells are maintained and grown outside the body in specially designed containers, such as test tubes and Petri dishes, and under precisely controlled conditions of temperature, humidity, nutrition and freedom from contamination.
Cell line: A cell culture developed from a single cell and therefore consisting of cells with a uniform genetic make-up.
Cell-cycle checkpoint: The checkpoints mark the end of each phase in the multi-phase process of cell division. At each checkpoint, ‘quality control’ has the chance to verify that the process has been accurately completed before allowing the cell to proceed to the next phase.
Checkpoint: See cell-cycle checkpoint.
Codon: A sequence of three consecutive nucleotides (the basic building blocks of DNA) on a gene that together form a unit. These units dictate which amino acids are to be used to create the protein that will carry out the function of the gene.
Clone: In the context of this book, a gene that is produced artificially from another gene, of which it is an identical copy.
DNA: Deoxyribonucleic acid, the material inside the nucleus of the cells of living organisms that carries genetic information.
Expression: The process by which an activated gene makes a protein or other product that carries out the function of that gene in the cell. If a gene is ‘over-expressed’, it implies there is an over-abundance of protein in the cell.
Gain of function: An expression used in reference to a genetic mutation that changes the gene product (e.g. protein) in such a way that it gains a new and abnormal function (see also loss of function).
‘Hallmarks of Cancer’: A seminal paper written by Robert Weinberg and Doug Hanahan in 2000 that describes the six characteristics common to all cancers, of whatever organ or origin. They revised the ‘Hallmarks’ in 2011, adding four more general principles.
Large T antigen: The gene in the DNA of the monkey virus SV40 that is responsible for causing cancer in the cells of the host species it infects.
Leukaemia: Cancer of the white blood cells, which are a vital component of the immune system (see also lymphoma).
Loss of function: An expression used in reference to a mutation that renders a gene useless – the mutant gene is either unable to make any protein or the protein it makes has no function. In most, if not all, tumour-suppressor genes other than p53, mutation leads to ‘loss of function’.
Lymphoma: Cancer originating in lymphoid tissue, a key component of the body’s immune system. Cancers of lymphocytes (lymphomas) and other white cells in the blood (leukaemia) together account for about 6.5 per cent of all cancers.
Malignant: In medical usage malignant means cancerous; able to spread to other parts of the body.
Metastasis: The spread of cancer cells from the original site to other parts of the body (hence metastases: secondary cancers).
Mutagen: A substance capable of causing mutation.
Mutant: Something that has undergone mutation (see below).
Mutation: A change of the DNA sequence within a gene or chromosome of an organism resulting in a new character or trait not found in the parental type; or the process by which such a change occurs.
Nucleotide: Nucleotides are the basic building blocks of DNA, which stack one on top of the other like nano-sized blocks of Lego to form the long ribbons of the double helix.
Oncogene: A gene that has the potential to cause cancer. Very often these are genes that have a normal role to play in the growth of cells, but that have sustained a mutation and lost the ability to respond to control signals.
Oncogenic: Causing development of a tumour or tumours.
Oncology: The study of cancer (hence oncologist, a doctor or scientist specialising in cancer).
‘Postdoc’: A postdoctoral scholar; an individual with a doctoral degree who is engaged in a temporary period of mentored research and/or scholarly training in order to acquire the professional skills needed for his or her future career.
Recombinant DNA: DNA that has been formed artificially by combining genetic material from different organisms.
Sarcoma: A type of cancer that forms in the connective or supportive tissues of the body such as muscle, bone and fatty tissue. Sarcomas account for less than 1 per cent of cancers.
Senescence: In this book the term is used to describe a state in which cell is no longer able to divide but remains alive and functioning.
Somatic mutation: A mutation in a mature cell that has occurred spontaneously during the course of life, as opposed to one that is inherited and will be present in all the cells, both normal and cancerous.
Tissue culture: The growth of tissues or cells removed from an organism. The living material is placed in a lab dish such as a test tube or Petri dish with a growth medium, typically a broth or agar gel, that contains special nutrients.
Transcription factor: A protein that binds to DNA at a specific site and controls the expression of a gene or genes in the vicinity, switching them on and off as appropriate.
Transformation: In this book, this term is used to describe the process by which a cell acquires the properties of cancer (commonly described also as ‘malignant transformation’).
Tumour suppressor: A gene whose function is to prevent cells from becoming malignant.
Wild type: Used in reference to a gene, this means the ‘normal’ gene that functions as nature intended, as opposed to the ‘mutant’ gene whose behaviour is aberrant.