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M

mab-5
C. elegans gene [see encoded homeodomain]
Macrolide antibiotics
Macromolecule
A molecule with a molecular weight of several thousand or more. Proteins, nucleic acids, cellulose, and starch are macromolecules.
Macrophage
Phagocytic cell derived from the monocyte.
Macrophage colony-stimulating factor
A cytokine (M-CSF). [More]
Magnetic resonance imaging (MRI)
Major histocompatibility complex (MHC)
A cluster of genes, some of whose products are involved in presenting antigens to T cells and also serve as the principal targets of graft rejection. Found in most, if not all, vertebrates. The MHC of humans is on chromosome 6 and is designated HLA. [diagram of the complex] [the class I and class II histocompatibility molecules]
Malignant
Refers to a cell that cannot stop dividing; also to the tumor that results. Cancerous.
Maltose
Mangold, Hilde
[discovery of the organizer]
Marijuana
Marsupial
Any of the order of pouched mammals such as opossums, wombats, and kangaroos. [pregnancy and birth]
Mast cell
Tissue equivalent of the basophil. [Role in allergies]
Matrix
(1) Extracellular material in which animal cells are embedded, especially those of connective tissue.(2) fluid contained within the inner membrane of mitochondria.
Medulla
Inner part of an organ.
Medulla oblongata
Megakaryocyte
Megaspore
Meiosis
The two successive cell divisions, with only one duplication of the chromosomes, that produces 4 cells, each containing one-half the number of chromosomes in the original cell. [More]
Melanocyte-stimulating hormone (MSH)
Melatonin
Memory cells
of immune system
Mendel
his second rule
Meninges
Menopause
Menstrual cycle
Meprobamate
Meristem
Embryonic plant tissue that produces new cells by repeated mitosis. [Examples and discussion]
Mesoderm
One of the three "germ layers" in embryonic development. [More]
Mesozoic era
Metabolism
Exchange of matter and energy between an organism and its environment and the transformation of this matter and energy within the organism.
[General discussion with links to specific examples] [Intermediary]
Metabolite
A substance used in or produced by metabolism.
Metamorphosis
Process of change (usually abrupt) from larval to adult form.
Metaphase
[mitosis][meiosis I]
Metastasis
A secondary growth of malignant (cancer) cells away from the site of the primary tumor.
Methanococcus jannaschii
[genome]
Methionine
[structure]
Micron (µ)
[defined]
Methyl group
[Structure] [methylation of DNA]
Microorganism
An organism of microscopic size such as bacteria, protozoans, and many algae. Also called a microbe.
Micropyle
Microspore
Microtubules
Discussion
Mifepristone
RU486
Millirem (mrem)
[defined]
Mineralocorticoids
Minerals
[nutritional requirements] [RDAs]
Mitochondrial stimulation factor (MSF)
[described]
Mitochondrion
[structure and functions][genome][diseases]
Mitosis
Nuclear division that follows duplication of the chromosomes, whereby each daughter nucleus has exactly the same chromosome content as the parent nucleus. [Discussion] [ and cell cycle]
Mixture
Material containing two or more substances, each of which retains its characteristic properties. The composition of a mixture is variable. A solution is a mixture. [Discussion]
Mole
Quantity of a substance whose weight in grams is numerically equal to the molecular weight of the substance (e.g., 18 g of water is 1 mole). [More]
Molecular weight
Sum of the atomic weights of the atoms in a molecule.
Molecule
Smallest particle of a covalently bonded element or compound that retains the properties of that substance.
Molt
To shed the outer covering.
Monoamine oxidase (MAO) inhibitors
Monoclonal antibodies
Monocyte
Blood-borne cell that becomes a macrophage in the tissues.
Monoecious
Having both female and male cones or flowers on the same plant. [More]
Monoglyceride
Glycerol carrying a single fatty acid.
Monomer
Simple molecular unit that can be linked with others to form a polymer. The glucose molecule is the monomer of starch.
Monosaccharide
A simple sugar, for example, glucose. [More]
Monotremes
View
Morphology
Study of structure.
Moss
life cycle
Motor unit
All the skeletal muscle fibers stimulated by a single motor neuron. [Discussion]
M-phase promoting factor (MPF)
[in cell cycle]
Multiple alleles
More than two alleles found at a give gene locus in a population.
Multiple factors
Nonallelic genes that affect the same trait in an additive fashion.
Multiple sclerosis
as autoimmune disease
Muscles
Discussion of skeletal, cardiac, and smooth muscle.
Muscular dystrophy
Mutagen
Agent that causes mutations. [Ionizing Radiation] [Testing chemical mutagens in bacteria] [Testing chemical mutagens in mice]
Mutation
Stable change in a gene. [More] [Germline vs somatic] [in B-cell antibody genes]
Mutualism
Close, mutually beneficial, association between two organisms of different species.
MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) [mutagenic by-product of water chlorination]
Myasthenia gravis
Autoimmune disorder of the neuromuscular junction. [More]
Mycelium
Mass of interwoven hyphae of a fungus.
Mycophenolate mofetil (CellCept)
Mycoplasma
[genitalium] [pneumoniae]
Mycorrhiza
The symbiotic association of a fungus with the roots of a plant.
Myelin sheath
Fatty covering around many axons. It is made up of layers of the plasma membrane of Schwann cells. [More]
Myeloma protein
The immunoglobulin (antibody) produced by a cancerous clone of plasma cells.
Myoneural junction
Junction between a motor neuron and a muscle fiber. Also called a neuromuscular junction. [Discussion]
Myofibrils
In skeletal and cardiac muscle.
Myosin
In muscle.
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