Lysosomes
A membrane-enclosed bag of hydrolytic enzymes found in the cytoplasm of eukaryotic cells.
Lymph vessel
A tubular passage for conveying lymph. Also known as lymphatic.
Lysozyme
An enzyme in perspiration, tears, and saliva that attacks bacterial cell walls.
Lytic cycle
A type of viral replication cycle resulting in the release of new phages by death or lysis of the
host cell.
M
M phase
The mitotic phase of the cell cycle, which includes mitosis and cytokinesis.
Macroevolution
Evolutionary change on a grand scale, encompassing the origin of novel designs,
evolutionary trends, adaptive radiation, and mass extinction.
Macromolecule
A giant molecule of living matter formed by the joining of smaller molecules, usually by
condensation synthesis. Polysaccharides, proteins, and nucleic acids are macromolecules.
Macronutrient
An inorganic nutrient required in large amounts for plant growth, such as nitrogen,
potassium, calcium, phosphorus, magnesium, and sulfur.
Macrophage
An amoeboid cell that moves through tissue fibers, engulfing bacteria and dead cells by
phagocytosis.
Major histocompatibility complex (MHC)
A large set of cell surface antigens encoded by a family of genes. Foreign MHC markers
trigger T-cell responses that may lead to the rejection of transplanted tissues and organs.