| Anti-oxidants - |
Compounds
that neutralize oxygen radicals. Some are enzymes like SOD while
others are nutrients such as vitamin C, vitamin E, and beta-carotene.
High levels of anti-oxidants have been associated with longer
life spans. |
| Anti-proliferative
genes - |
Genes
that inhibit cell division or proliferation; also known as tumor
suppressor genes. |
| Average
life span - |
The
average number of years that members of a population live. |
| Biomarkers - |
Biological
changes that characterize the aging process; because biomarkers
are considered a better measure of aging than chronological
time, studies are underway to identify biomarkers in cells,
tissues, and organs. |
| Caloric
restriction - |
An
experimental approach to studying longevity in which life spans
of laboratory animals have been extended by reducing calories
while the necessary level of nutrients is maintained. |
| Cell
senescence - |
The
stage at which a cell has stopped dividing permanently. |
| Chromosomes - |
Structures
in the cell's nucleus, made up of protein and DNA, that contain
the genes. |
| DNA
(deoxyribonucleic acid) - |
A
large molecule that carries the genetic information necessary
for all cellular functions, including the building of proteins.
Damage to DNA and the rate at which this damage is repaired
may help determine the rate of aging. |
| Free
radicals - |
Molecules
with unpaired electrons that react readily with other molecules.
Oxygen-free radicals, produced during metabolism, damage cells
and may be responsible for aging in tissues and organs. |
| Gene - |
A
segment of DNA that contains the "code" for a specific protein
or other product. |
| Gene
expression - |
The
process by which genes are transcribed and translated into proteins.
Age-related changes in gene expression may account for some
of the phenomena of aging. |
| Glycation - |
The
process by which glucose links with proteins and causes them
to bind together, thus stiffening tissues and leading to the
complications of diabetes and perhaps some of the physiologic
problems associated with aging. |
| Hayflick
limit - |
The
finite number of divisions of which at cell is capable. |
| Interleukins - |
Substances
secreted by lymphocytes; their levels vary with age. |
| Lymphocytes - |
Small
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
life span - |
The
greatest age reached by any member of a given species. |
| Mitochondria - |
Cell
organelles that metabolize sugars into energy. Mitochondria
also contain DNA, which is damaged by the high level of free
radicals produced in the mitochondria. |
| Proliferative
genes - |
Genes
that promote cell division or proliferation; also known as oncogenes. |
| Photoaging - |
The
process initiated by sunlight through which the skin becomes
drier and loses elasticity. Photoaging is being studied for
clues to aging because it has the same effect as normal aging
on certain skin cells. |
| Proteins - |
Molecules
made up of amino acids arranged in a specific order determined
by the genetic code. Proteins are essential for all life processes.
Certain ones, such as the enzymes that protect against free
radicals and the lymphokines produced in the immune system,
are being studied extensively by gerontologists. |
| Telomeres - |
Repeated
DNA sequences found at the ends of chromosomes; telomeres shorten
each time a cell divides. |
