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antiviral drug

(Encyclopedia)antiviral drug, any of several drugs used to treat viral infections. The drugs act by interfering with a virus's ability to enter a host cell and replicate itself with the host cell's DNA. Some drugs ...

Krebs cycle

(Encyclopedia)Krebs cycle, series of chemical reactions carried out in the living cell; in most higher animals, including humans, it is essential for the oxidative metabolism of glucose and other simple sugars. The...

impotence

(Encyclopedia)impotence imˈpətəns [key], inhibited sexual excitement in a man during sexual activity that, despite an unaffected desire for sex, results in inability to attain or maintain a penile erection. Know...

Alzheimer's disease

(Encyclopedia)Alzheimer's disease ălsˈhīˌmərz, ôls– [key], degenerative disease of nerve cells in the cerebral cortex that leads to atrophy of the brain and senile dementia and, ultimately, death. The disea...

respiration

(Encyclopedia)CE5 Respiratory system respiration, process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is tran...

gene

(Encyclopedia)gene, the structural unit of inheritance in living organisms. A gene is, in essence, a segment of DNA that has a particular purpose, i.e., that codes for (contains the chemical information necessary f...

metal

(Encyclopedia)metal, chemical element displaying certain properties by which it is normally distinguished from a nonmetal, notably its metallic luster, the capacity to lose electrons and form a positive ion, and th...

insulin

(Encyclopedia)insulin, hormone secreted by the β cells of the islets of Langerhans, specific groups of cells in the pancreas. Insufficiency of insulin in the body results in diabetes. Insulin was one of the first ...

nucleic acid

(Encyclopedia)CE5 Replication of strands of DNA CE5 nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replica...

milk, food

(Encyclopedia)milk, liquid secreted by the mammary glands of female mammals as food for their young. The milk of the cow is most widely used by humans, but the milk of the mare, goat, ewe, buffalo, camel, ass, zebr...