Science, Tech, Math › Science Cell Biology Glossary Share Flipboard Email Print ANDRZEJ WOJCICKI/Science Photo Library/Getty Images Science Biology Cell Biology Basics Genetics Organisms Anatomy Physiology Botany Ecology Chemistry Physics Geology Astronomy Weather & Climate By Regina Bailey Biology Expert B.A., Biology, Emory University A.S., Nursing, Chattahoochee Technical College Regina Bailey is a board-certified registered nurse, science writer and educator. Her work has been featured in "Kaplan AP Biology" and "The Internet for Cellular and Molecular Biologists." our editorial process Regina Bailey Updated June 05, 2019 Many biology students often wonder about the meanings of certain biology terms and words. What is a nucleus? What are sister chromatids? What is the cytoskeleton and what does it do? The Cell Biology Glossary is a good resource for finding succinct, practical, and meaningful biology definitions for various cell biology terms. Below is a list of common cell biology terms. Cell Biology Glossary Anaphase - a stage in mitosis where chromosomes begin moving to opposite ends (poles) of the cell. Animal Cells - eukaryotic cells that contain various membrane-bound organelles. Allele - an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. Apoptosis - a controlled sequence of steps in which cells signal self-termination. Asters - radial microtubule arrays found in animal cells that help to manipulate chromosomes during cell division. Biology - the study of living organisms. Cell - the fundamental unit of life. Cellular Respiration - a process by which cells harvest the energy stored in food. Cell Biology - the subdiscipline of biology that focuses on the study of the basic unit of life, the cell. Cell Cycle - the life cycle of a dividing cell, including Interphase and the M phase or Mitotic phase (mitosis and cytokinesis). Cell Membrane - a thin semi-permeable membrane that surrounds the cytoplasm of a cell. Cell Theory - one of the five basic principles of biology, stating that the cell is the basic unit of life. Centrioles - cylindrical structures that are composed of groupings of microtubules arranged in a 9 + 3 pattern. Centromere - a region on a chromosome that joins two sister chromatids. Chromatid - one of two identical copies of a replicated chromosome. Chromatin - the mass of genetic material composed of DNA and proteins that condense to form chromosomes during eukaryotic cell division. Chromosome - a long, stringy aggregate of genes that carries heredity information (DNA) and is formed from condensed chromatin. Cilia and Flagella - protrusions from some cells that aid in cellular locomotion. Cytokinesis - the division of the cytoplasm that produces distinct daughter cells. Cytoplasm - all of the contents outside of the nucleus and enclosed within the cell membrane of a cell. Cytoskeleton - a network of fibers throughout the cell's cytoplasm that helps the cell maintain its shape and gives support to the cell. Cytosol - semi-fluid component of a cell's cytoplasm. Daughter Cell - a cell resulting from the replication and division of a single parent cell. Daughter Chromosome - a chromosome that results from the separation of sister chromatids during cell division. Diploid Cell - a cell that contains two sets of chromosomes—one set of chromosomes is donated from each parent. Endoplasmic Reticulum - a network of tubules and flattened sacs that serve a variety of functions in the cell. Gametes - reproductive cells that unite during sexual reproduction to form a new cell called a zygote. Gene Theory - one of the five basic principles of biology, stating that traits are inherited through gene transmission. Genes - segments of DNA located on chromosomes that exist in alternative forms called alleles. Golgi Complex - the cell organelle that is responsible for manufacturing, warehousing, and shipping certain cellular products. Haploid Cell - a cell that contains one complete set of chromosomes. Interphase - the stage in the cell cycle where a cell doubles in size and synthesizes DNA in preparation for cell division. Lysosomes - the membranous sacs of enzymes that can digest cellular macromolecules. Meiosis - a two-part cell division process in organisms that sexually reproduce, resulting in gametes with one-half the number of chromosomes of the parent cell. Metaphase - the stage in cell division where chromosomes align along the metaphase plate in the center of the cell. Microtubules - fibrous, hollow rods that function primarily to help support and shape the cell. Mitochondria - cell organelles that convert energy into forms that are usable by the cell. Mitosis - a phase of the cell cycle that involves the separation of nuclear chromosomes followed by cytokinesis. Nucleus - a membrane-bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. Organelles - tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Peroxisomes - cell structures that contain enzymes that produce hydrogen peroxide as a by-product. Plant Cells - eukaryotic cells that contain various membrane-bound organelles. They are distinct from animal cells, containing various structures not found in animal cells. Polar Fibers - spindle fibers that extend from the two poles of a dividing cell. Prokaryotes - single-celled organisms that are the earliest and most primitive forms of life on earth. Prophase - the stage in cell division where chromatin condenses into discrete chromosomes. Ribosomes - cell organelles that are responsible for assembling proteins. Sister Chromatids - two identical copies of a single chromosome that are connected by a centromere. Spindle Fibers - aggregates of microtubules that move chromosomes during cell division. Telophase - the stage in cell division when the nucleus of one cell is divided equally into two nuclei.