Biology

microtubule is a hollow, cylindrical protein filament that forms part of the cell’s cytoskeleton and participates in intracellular transport and chromosome movement during cell division. Composed of tubulin subunits, microtubules are dynamic, growing and shrinking as they polymerize and depolymerize, and they provide structural support and track-like routes for motor proteins. They are essential for maintaining cell shape and enabling processes such as mitosis and meiosis.

Mitochondria are membrane-bound organelles found in most eukaryotic cells, producing most of the cell’s supply of adenosine triphosphate (ATP) through cellular respiration. They are essential for energy metabolism, signaling, and apoptosis regulation. The term refers to the organelle’s thread-like shape and its role as the cell’s powerhouses, containing their own DNA and ribosomes.

Mitochondrial is an adjective relating to mitochondria, the energy-producing structures within cells. It is used in biology and medicine to describe things associated with mitochondria (e.g., mitochondrial DNA). The term conveys a cellular, genetic, and biochemical focus and is often used in expert discussions or scientific writing.

Mitochondrion is a membrane-bound organelle found in most eukaryotic cells, often described as the powerhouse of the cell because it generates most of the cell’s supply of adenosine triphosphate (ATP). It contains its own DNA and ribosomes, enabling a degree of independence within the cellular environment. The term is used in biology, biochemistry, and medicine, typically in scientific and academic contexts.

Mitosis is a fundamental stage of cell division in which the nucleus divides into two genetically identical nuclei, followed by cytoplasmic division. It ensures equal distribution of a cell’s genetic material into two daughter cells. The process is essential for growth, development, and tissue repair in multicellular organisms.

Monosomy is a chromosomal condition in which a diploid cell has only one copy of a particular chromosome instead of the usual two. It is a form of aneuploidy and can lead to developmental abnormalities or miscarriage, depending on which chromosome is affected. The term is commonly used in genetics, medicine, and prenatal diagnoses, and is often contrasted with monosomy rescue and trisomy conditions.

Morphogenesis is the biological process that causes an organism or tissue to develop its shape. It involves the organization of cells and tissues during development, guiding patterns of growth and form from embryonic to mature states. The term is used across biology, developmental biology, and tissue engineering to describe how structure emerges over time.

Myelin is a fatty insulating sheath that surrounds nerve fibers, accelerating electrical signaling in the nervous system. It is produced by glial cells and plays a crucial role in rapid, saltatory conduction. In science contexts, it’s discussed regarding development, disease (like demyelinating disorders), and neural plasticity.

Myelination is the process by which nerve fibers are insulated with a myelin sheath, increasing the speed and efficiency of electrical signal transmission in the nervous system. It develops progressively, beginning in early development and continuing into adulthood, shaping neural connectivity and cognitive function. In neuroscience, myelination is a key factor in learning, plasticity, and overall neural communication efficiency.

Myoblast is a primitive muscle-forming cell that fuses with others to create muscle fibers during development and repair. It originates from mesodermal lineage and differentiates into myocytes; the term is used in biology and medicine to describe precursor cells involved in muscle formation and regeneration. In research contexts, myoblasts are studied to understand muscular disorders and tissue engineering.

A myocyte is a muscle cell, the basic unit of muscle tissue capable of contraction. It is typically elongated and highly specialized for electrical excitability and mechanical force generation, and it forms the fibers that compose striated and smooth muscles. In most contexts, it refers to a cardiac or skeletal muscle cell essential to movement and heart function.

Myofibril is a basic rod-like unit of a muscle cell that contracts in coordinated fashion as part of a myofibrillar bundle. It comprises repeating sarcomeres, containing actin and myosin filaments, whose interactions produce contraction. Each myofibril runs along the muscle fiber, enabling efficient force generation essential to movement.

Necrosis refers to the premature death of cells or tissue in a part of the body, due to factors like injury, infection, or loss of blood supply. It describes a pathological process that can lead to inflammation, decay, and potential damage to surrounding tissues. The term is used in medical contexts to distinguish cell death from apoptosis and other forms of tissue loss.

Neuroglia are non-neuronal cells in the nervous system that provide support, protection, and nutrition to neurons. They include various subtypes such as astrocytes, oligodendrocytes, microglia, and Schwann cells, each with specialized roles. Collectively, neuroglia maintain homeostasis, form myelin, and participate in signal modulation and repair processes within the brain and peripheral nerves.

Neuron is a specialized cell that transmits nerve impulses in the nervous system. It typically features a cell body, dendrites, and an axon, enabling communication within neural networks. In scientific contexts, neurons are discussed in terms of structure, signaling, and connectivity, forming the fundamental units of brain and nervous system function.

A chemical that facilitates communication between neurons by transmitting signals across synapses. Neurotransmitters influence mood, cognition, and motor control and include substances like dopamine, serotonin, and glutamate. They are released from presynaptic neurons in response to electrical activity and bind to receptors on postsynaptic cells, shaping neural circuits and responses.

Neutrophil is a type of white blood cell that defends the body by ingesting bacteria and other invaders. It is the most abundant circulating leukocyte in humans and is key to the innate immune response. The term combines roots referring to its neutral staining properties and its cellular identity.

Nitrogenase is an enzyme complex essential for the biological fixation of atmospheric nitrogen into ammonia, a form usable by living organisms. It catalyzes the reduction of N2, a reaction that requires substantial energy input, typically from ATP, and operates within certain microbial systems. The term denotes both the enzyme and its activity, foundational to the global nitrogen cycle.

nucleoid (nuk-lee-oyd) refers to the irregularly-shaped, DNA-containing region in a prokaryotic cell where the chromosome is concentrated, not enclosed by a membrane. It functions as the genetic control center, organizing and guiding replication and transcription. The term can also appear in advanced cellular biology contexts, distinguishing this non-membrane-bound region from true nuclei in eukaryotes.