Mapping, gene
The charting of the positions of genes on a DNA molecule or chromosome and the distance, in linkage units or physical units, between genes.
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- Marasmus
Wasting away, as occurs with children who have kwashiorkor. Also called cachexia, is usually a result of protein and calorie deficiency.
- Marfan syndrome
An inherited disorder of connective tissue that is characterized by abnormalities of the eyes, skeleton, and cardiovascular system. Nearsightedness (myopia) is the most common eye feature in Marfan syndrome. Displacement of the lens from the center of the pupil occurs in more than half of patients. Patients with Marfan syndrome have an increased risk for […]
- Marijuana
the hemp plant cannabis sativa. The pharmacologically active ingredient in marijuana is tetra-hydro-cannabinol (THC). Marijuana is used to heighten perception, affect mood, and relax. Many people think marijuana is harmless, but it is not. Signs of marijuana use include red eyes, lethargy, and uncoordinated body movements. The long-term effects may include decrease in motivation and […]
- Mark of Cain
The mark that God set upon Cain, the eldest son of Adam. According to the Book of Genesis in the Bible, God rejected Cain’s grain offering while accepting the animal offering of his brother Abel. Out of jealousy, Cain murdered his brother and was compelled by God to wander the earth as “a fugitive and […]
- Marker chromosome
An abnormal chromosome that is distinctive in appearance but not fully identified. A marker chromosome is not necessarily a marker for a specific disease or abnormality, but it can be distinguished under the microscope from all the normal human chromosomes. For example, the fragile X (FRAXA) chromosome was once called the marker X.