Antioxidants – Compounds that may protect cells from oxygen free radicals by preventing or slowing the process of oxidation. Some antioxidants are enzyme proteins like superoxide dismutase (SOD) and catalase, while others are nutrients, such as vitamin C.
Calorie restriction – A diet that is lower by a specific percent of calories than the normal diet, but includes all essential nutrients. At this time calorie restriction is an experimental intervention being studied to determine its impact on health and longevity.
Cell senescence – A process in which a cell turns off its capacity to produce new cells, stops dividing, and has limited function. Cell senescence may contribute to aging, but it may also be a protective mechanism against cancer (a disease state in which cells continue to divide without control).
Centenarian – A person who has lived at least 100 years.
Chromosome – A structure inside cells containing DNA, which carries our genetic information and is responsible for heritable traits.
DNA – Abbreviation for deoxyribonucleic acid; DNA contains the genetic code for all animals and plants, from single-cell organisms to humans.
Enzyme – A protein that increases the rate of a specific chemical reaction.
Fibroblast – One of the major cell types found in skin and other tissues. Fibroblasts secrete molecules that have important structural properties for tissues and organs, and they change with age.
Free radicals – Unstable molecules that react readily with other molecules to try to become stable. Oxygen free radicals are produced normally when food is metabolized and may cause damage to cells. Over a lifetime, this damage may contribute to aging.
Gene – A region of DNA containing code that can be read to make proteins in the cell. Genes are responsible for many heritable traits.
Immunosenescence – The age-related decline in functions of the immune system.
Life expectancy – The average number of years that members of a population (or species) live; also known as average lifespan.
Lymphocytes – White blood cells that are important to the immune system. A decline in lymphocyte function with advancing age is being studied for insights into aging and disease.
Maximum lifespan – The greatest age reached by any member of a given population (or species).
Mitochondria – Cell organelles that produce energy necessary for life from the foods we eat. Mitochondria contain DNA, which may be damaged by oxygen free radicals produced during this process. Damage of mitochondrial DNA may contribute to aging. Mitochondria also are involved in controlling cell death.
Proteins – Molecules arranged in a specific order determined by DNA. Proteins are essential for all life processes. Certain proteins, such as those protecting against free radicals and those produced by the immune system, are studied extensively by gerontologists.
Stem cells – Cells with the potential to become many different types of cells found in the body. Stem cells are also able to replicate almost indefinitely without becoming abnormal.
Telomerase – An enzyme that restores telomeres to the ends of chromosomes in certain cells, such as egg and sperm cells. This telomere lengthening ensures that the cells can continue to divide and multiply.
Telomeres – Repeated short, non-coding sequences of DNA at each end of a chromosome. Telomeres protect the chromosome from damage and shorten each time a cell divides.