The trading of fragments of genetic material between chromosomes before the egg and sperm cells are created. Key features of recombination include the point-to-point association of paired chromosomes (synapsis), followed by the visible exchange of segments (crossing over) at X-shaped crosspoints (chiasmata). Recombination is the principal way of creating genetic diversity between generations. Recombination ensures that children receive a different genetic makeup than their parents.
- Recommended Daily Allowance
Popular name for the Recommended Dietary Allowance (RDA).
A vaccine against hepatitis B (hep B) to stimulate the body’s immune system to produce antibodies against the hep B virus.
- Recommended Dietary Allowance
The RDA, the estimated amount of a nutrient (or calories) per day considered necessary for the maintenance of good health by the Food and Nutrition Board of the National Research Council/ National Academy of Sciences. The RDA is updated periodically to reflect new knowledge. It is popularly called the Recommended Daily Allowance.
Reappearance, as of a rash or arthritis.
- Rectal (adjective)
Having to do with the rectum, the last 6 to 8 inches of the large intestine that serves to store solid waste until it leaves the body through the anus. The word “rectal” comes from the Latin “rectus” meaning “straight” (which the human rectum is not).