in biology, the smallest unit that can carry on all of the processes of life; cells are covered by a membrane and contain DNA and cytoplasm.
the theory that states that all living things are made up of one or more cells, that cells are the basic units units of organisms, that each cell in a multicellular organism has a specific job, and that cells come from existing cells.
or cell membrane, the cell's outter boundry.
the region of the cell within the membrane that includes the fluid, the cytoskeleton, and all of the organelles except for the nucleus.
the soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covored with membranes.
in a eukaryotic cell, a membrane bound organelle that contains the cell's DNA and that has a role in processes such as growth, metabolism, and reproduction.
a single celled organism that has no nucleus and has no membrane bound organelles;examples include bacteria and archaea.
an organism made up of cells that have a nucleus enclosed by a membrane, multiple chromosomes, and a mitotic cycle; eukaryotes include animals, plants and fungi but not bacteria or archaea.
one of the small bodies that are found in the cytoplasm of a cell and that are specialized to perform a specific function.
a collection of specialized cells and cell products that perform a specific function.
a collection of tissues that carry out a specialized function of the body.
a group of organs that accomplish related tasks.
a double layer of phospholipids that makes up plasma and organelle membranes.
in a eukaryotic cell, one of the structures in the nucleus that are made up of DNA and protein; in a prokaryotic cell, the main ring of DNA.
the double membrane that surrounds the nucleus of a eukaryotic cell.
the part of a eukaryotic nucleus where ribosomal RNA is synthesized.
a cell organelle composed of RNA and protein; the site of protein synthesis.
in eukaryotic cells, the cell organelle that is surrounded by two membranes and that is the site of cellular respiration, which produces ATP.
a system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids.
another system of flattened, membranous sacs.
a cell organelle that contains digestive enzymes and that buds from the golgi apparatus.
the cytoplasmic network of protein filaments and tubes that plays an essential role in cell movement, shape, and division.
one of the small, tubular fibers composed of the protein tubulin that are found in the cytoplasm of eukaryotic cells, that compose the cytoskeleton, and that play a role in cell structure and movement.
a fiber found inside eukaryotic cells that is composed mainly of the protein actin and that has a role in cell structure and movement.
a hairlike structure arranged in tightly packed rows that projects from the surface of some cells.
a long, hairlike structure that grows out of a cell and enables the cell to move.
an organelle that is composed of two short microtubules at right angles to each other and that has an active role in mitosis.
a rigid structure that surrounds the cell membrane and provides support to the cell.
in some protists and in most plant cell, a large, fluid filled organelle that stores water, enzymes, metabolic wastes, and other materials.
an organelle of plant cells that contains specific substances and performs specific functions for the cell; examples include chloroplasts and chromoplasts.
an organelle found in plant and algae cells where photosynthesis occurs.
a membrane system found within chloroplasts that contains the components for photosynthesis.
a green pigment that is present in most plant cells, that gives plants their characteristic green color, and that reacts with sunlight, carbon dioxide, and water to form carbohydrates.