Cell
The smallest structural and functional unit of an organism
cell theory
A theory first stated by Matthias Schleiden and Theodor Schwann, that cells are the basic units of structure and function in living organisms.
cell membrane
A membrane surrounding the cytoplasm of a cell.
cell wall
A rigid layer of covering lying outside the plasma membrane of the cells of plants, fungi, and bacteria.
nucleus
A dense organelle present in most eukaryotic cells
cytoplasm
The material or protoplasm within a living cell
prokaryote
A microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles.
eukaryote
An organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus.
organelle
Any of a number of organized or specialized structures within a living cell.
chromatin
the material of which the chromosomes of organisms other than bacteria.
chromosome
A threadlike structure of nucleic acids and protein found in the nucleus of most living cells.
nucleolus
A small dense spherical structure in the nucleus of a cell.
nuclear envelope
The double-layered membrane enclosing the nucleus of a eukaryotic cell.
cytoskeleton
A microscopic network of protein filaments and tubules in the cytoplasm of many living cells.
microtubule
a microscopic tubular structure present in numbers in the cytoplasm of cells
microfilament
A small rodlike structure, about 4–7 nanometers in diameter.
ribosome
A minute particle consisting of RNA and associated proteins.
endoplasmic reticulum
A network of membranous tubules within the cytoplasm of a eukaryotic cell.
Golgi apparatus
A complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells.
lysosome
An organelle in the cytoplasm of eukaryotic cells.
vacuole
A space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.
mitochondria
An organelle found in large numbers in most cells.
chloroplast
A plastid that contains chlorophyll and in which photosynthesis takes place.
cell specialization
An adaptation to do a particular job in a cell.
tissue
Any of the distinct types of material of which animals or plants are made, consisting of specialized cells and their products.
organ
A part of an organism that is typically self-contained and has a specific vital function.
organ system
A group of organs that work together to perform one or more functions.