Biology 10: Cell Division, Mitosis, and Cellular Regulation

Comprehensive vocabulary flashcards covering the cell cycle, stages of mitosis, tissue renewal rates, stem cells, tumor classification, and cellular regulation.

Meiosis

A specialized type of cell division in eukaryotic organisms that reduces the chromosome number by half, transforming a single diploid cell into four genetically unique haploid gametes (sperm or egg cells).

Mitosis

The process where a single eukaryotic cell divides to produce two genetically identical daughter cells, each with the same number of chromosomes as the parent cell; essential for growth, tissue repair, regeneration, and asexual reproduction.

Sister Chromatids

Two identical strands formed when a cell copies its genetic material during the S Phase, creating an X-shaped structure held tightly together at the centromere.

Centromere

The specialized DNA sequence and protein structure that links sister chromatids together, forming the narrowest constriction point (the "waist") of a duplicated X-shaped chromosome.

Interphase

The cell cycle phase driven by proteins and checkpoint mechanisms where cells spend $90\%$ of their time carrying out normal metabolic functions such as making proteins, secreting substances, and removing toxins.

G0 Phase (GO)

The resting or operational stage where a cell performs its specialized physiological job (such as pancreas cells secreting insulin or liver cells breaking down blood toxins) rather than preparing to divide.

G1 Phase ("First Gap")

A cell cycle phase marked by a cellular "growth spurt" where the cell increases in size and synthesizes new proteins as well as organelles.

S Phase ("Synthesis")

The stage of interphase where genetic material is replicated to produce two copies of DNA within the cell, during which normal cellular functional efficiency slows down.

G2 Phase ("Second Gap")

The phase in which centrosomes organize organelles and DNA to ensure that the original cell and the upcoming daughter cell will divide internal components equally.

M Phase (Mitotic Phase)

The division phase where the cell nucleus divides in two, distributing a complete copy of the cell's genetic code by pushing copied chromosomes to opposite ends of the cell.

Cytokinesis

The physical splitting of the cytoplasm ("moving cell"); in animal cells, the membrane cinches like a drawstring, whereas in plant cells, a rigid cell wall forms down the middle.

Prophase

The first phase of mitosis where duplicated DNA condenses into visible chromatids and X-shaped chromosomes, and mitotic spindles begin to form between centrosomes drifting to opposite poles.

Mitotic Spindles

Long, thin protein strands that assemble between drifting centrosomes during prophase and attach to the centromeres of chromosomes to align and move them.

Metaphase

The mitotic phase where mitotic spindles slide into the center of the cell and align chromosomes along the cellular midline by attaching to their centromeres.

Anaphase

A rapid stage lasting only a few minutes where proteins joining sister chromatids split, allowing individual chromosomes to be pulled backward to opposite ends of the cell while the spindle largely disassembles.

Telophase

The final stage of mitosis where two new nuclear membranes enclose the separated sets of chromosomes, and the tightly packed DNA uncoils back into a loose, thread-like form.

Mitotic Rate

A quantitative measurement of how rapidly a cell population divides, calculated by counting the number of cells undergoing mitosis within a specific area or tissue sample.

Stratum Basale

The deepest layer of the epidermis where stem cells divide continuously, producing cells that take $40$ to $56$ days in adults ($28$ to $40$ days in younger adults) to migrate upward and shed from the stratum corneum.

Post-mitotic Cells

Cells such as skeletal muscle fibers and mature neurons that have a mitotic rate of essentially zero, do not divide under normal circumstances, and rely on non-mitotic mechanisms for tissue repair.

Stem Cells

Unspecialized or undifferentiated cells capable of continuous division and transformation into specialized cell lineages, acting as an internal repair and maintenance system.

Embryonic Stem Cells (ESCs)

Pluripotent stem cells derived from early-stage blastocysts that retain the potential to differentiate into virtually any cell type found in the organism.

Adult (Somatic) Stem Cells

Multipotent cells residing within specific tissues (such as skin or bone marrow) that function primarily to replace cells lost to everyday wear, tear, or physical injury.

Cancer

A diverse group of diseases marked by uncontrolled cellular growth and tissue invasion, originating from a breakdown in the genetic checks and balances controlling division and death.

Benign Tumors

Non-cancerous tissue masses that do not invade surrounding tissues or spread to distant sites (metastasize), and typically do not recur following surgical excision.

Malignant Tumors

Cancerous masses composed of cells that aggressively infiltrate adjacent structures and can detach to travel through blood or lymph vessels to establish secondary growths.

Metastasis

The biological process in which malignant cells separate from a primary tumor, navigate through the bloodstream or lymphatic network, and establish secondary tumors in distant anatomical sites.

Oncogene

A mutated form of a gene (originally a proto-oncogene) that acts like a jammed accelerator pedal in a vehicle, stimulating unceasing and unregulated cell proliferation.

Cell Differentiation

The developmental process through which an unspecialized cell matures into a distinct cell type with specialized functions by selectively activating or silencing specific genes on its shared DNA genome.