Biology

• Cell Division


  The process by which a parent cell divides into two or more daughter cells. It is essential for growth, repair, and reproduction in organisms.
• Asexual Reproduction


  A type of reproduction involving only one parent that results in genetically identical offspring.
• Sexual Reproduction


  A type of reproduction involving the fusion of two different gametes (sperm and egg), resulting in offspring that have genetic material from both parents.
• Chromosome


  A thread-like structure composed of DNA and protein that contains genetic information. In eukaryotic cells, chromosomes are found in the nucleus.
• Chromatin


  The material that makes up chromosomes. It consists of DNA and proteins called histones.
• Cell Cycle


  The sequence of events that take place in a cell leading to its growth, replication of DNA, and division. It includes interphase, mitosis, and cytokinesis.
• Interphase


  The phase of the cell cycle where the cell grows and replicates its DNA in preparation for mitosis.
• Mitosis


  The process by which a eukaryotic cell divides its nucleus and distributes its chromosomes to two daughter nuclei, ensuring each daughter cell receives a complete set of chromosomes.
• Cytokinesis


  The division of the cytoplasm and the cell membrane that follows the division of the nucleus, resulting in two separate daughter cells.
• Prophase


  The first stage of mitosis, during which the chromosomes condense, the nuclear envelope breaks down, and the spindle apparatus forms.
• Chromatid


  One of the two identical halves of a duplicated chromosome.
• Centromere


  The region of a chromosome where the two sister chromatids are held together and where the spindle fibers attach during mitosis.
• Centriole


  A structure in animal cells that helps organize cell division by forming spindle fibers.
• Metaphase


  The stage of mitosis where chromosomes line up in the middle of the cell.
• Anaphase


  The stage of mitosis where sister chromatids are separated and pulled to opposite poles of the cell.
• Telophase


  The final stage of mitosis, where chromosomes begin to decondense, nuclear envelopes re-form around each set of chromosomes, and the cell begins to divide.
• Growth Factor


  A naturally occurring substance that stimulates cellular growth, proliferation, and differentiation.
• Cyclin


  A family of proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase (CDK) enzymes.
• Apoptosis


  Programmed cell death that occurs in multicellular organisms as a normal and controlled part of an organism's growth or development.
• Cancer


  A disease caused by uncontrolled division of abnormal cells in a part of the body.
• Tumor


  A mass of tissue that's formed by an accumulation of abnormal cells. Tumors can be benign (non-cancerous) or malignant (cancerous).
• Embryo


  An early stage of development in multicellular organisms. In humans, it refers to the stage from fertilization until about eight weeks.
• Differentiation


  The process by which cells become specialized in structure and function.
• Totipotent


  Cells that have the potential to develop into any type of cell in the body or an entire organism.
• Blastocyst


  A structure formed in the early development of mammals, containing an inner cell mass that can develop into the embryo.
• Pluripotent


  Cells that can develop into most, but not all, of the body's cell types.
• Stem Cell


  Precursor cells that have the capacity to self-renew and to generate multiple mature cell types.
• Multipotent


  Cells that can develop into multiple, but limited, cell types.
• Genetics


  The study of heredity and the variation of inherited characteristics.
• Fertilization


  The process by which a sperm cell and an egg cell combine to form a zygote, initiating the development of a new organism.
• Trait


  A characteristic or feature of an organism that can be inherited.
• Hybrid


  An organism that has two different alleles for a particular trait; the offspring of two different species or varieties.
• Gene


  A segment of DNA that contains coding for a protein or RNA molecule; a unit of heredity.
• Allele


  One of the different forms of a gene that can exist at a single locus.
• Principle of Dominance


  Mendelian principle stating that one allele may mask the expression of another allele.
• Segregation


  The process during meiosis where homologous chromosomes are separated into different gametes.
• Gamete


  A sex cell (sperm or egg) that contains half the genetic material of an organism.
• Probability


  The likelihood that a particular event will occur, often used in genetics to predict the outcome of genetic crosses.
• Homozygous


  Having two identical alleles for a particular gene.
• Heterozygous


  Having two different alleles for a particular gene.