cell membraneThe outer lining of a cell, built of lipid and protein. Its other name is the plasma membrane. It separates the inside of the cell from the outside and controls what enters and leaves.
cell wallThe stiff cellulose case around a plant cell. It lies just outside the cell membrane and gives support, shape and protection. Fungi, algae and most bacteria have cell walls too. Animal cells have none.
chloroplastThe green organelle where light energy becomes food. Found mostly in the cells of plants and algae. Its green pigment is chlorophyll. Some one-celled algae have a single chloroplast; a wheat cell can have up to 100.
cytoplasmThe thick fluid that fills a cell, mostly water. It is about 80 percent water. Its main parts are a gel-like fluid, the cytosol, and the structures that sit in it. In a cell with a nucleus, the nucleus is not counted as part of it.
Golgi apparatusFinishes proteins from the ER and sends them onward. Also called the Golgi body. It looks like a stack of membranes near the nucleus. Camillo Golgi, an Italian biologist, identified it in 1898.
Show all 36 terms (31 more)
Main organelles, continued
lysosomeAn acidic bag where worn cell parts are taken apart. It holds more than 60 kinds of digestive enzymes. An animal cell normally has hundreds of lysosomes; plant cells rarely have any.
mitochondrionWhere oxygen is used to turn food energy into ATP. The plural is mitochondria. Each has two membranes and a small chromosome of its own, generally inherited from the mother only.
nucleusThe chromosomes' home, with pores in its envelope. It holds nearly all of the cell's DNA. Pores in its double membrane let chosen molecules in and out. The red blood cells of mammals have no nucleus.
ribosomeA knot of RNA and protein where new proteins grow. It is built of RNA and protein, in a small and a large subunit. Some ribosomes float free in the cytoplasm and others sit on the rough ER.
rough ERA maze of flat sacs coated with ribosomes. ER is short for endoplasmic reticulum, a network of membranes. The ribosomes on the rough kind build proteins that will leave the cell or join its membrane.
smooth ERRibosome-free tubes where lipids are made. With no ribosomes on it, it looks smooth. Its membranes form tubes where the rough kind forms flat sacs.
vacuoleThe bubble that manages a plant's water balance. One vacuole may fill most of the inside of a plant cell. Animal cells have small vacuoles that help set waste products aside.
How they work 12
autophagyA cell digesting and recycling pieces of itself. The word is built from Greek for self-devouring. The unneeded or faulty parts are delivered to lysosomes, which break them down.
cell fractionationBreaking cells open to sort their parts. The broken cells are spun in a centrifuge, then the liquid left over is spun again with more force. Each spin brings down another kind of part.
chaperoneA helper that keeps new proteins from clumping. Chaperones assist large proteins as they fold. Many are called heat shock proteins, because heat makes proteins more likely to clump.
compartmentA closed space in a cell, walled off by membrane. Separate compartments let a cell carry out different chemical jobs at the same time. Each can keep its own acidity and its own set of enzymes.
cytoplasmic streamingThe flow that moves organelles around a large cell. Also called cyclosis. It is seen in cells larger than about 0.1 millimeter, where diffusion alone would move molecules too slowly.
glycosylationThe attaching of sugar chains to a protein. Most proteins made on the rough ER have sugars attached. Enzymes in the Golgi apparatus attach more as the proteins pass through it.
organelleAny part of a cell that has a task to carry out. The name likens these parts to the organs of a body. Some are wrapped in a membrane of their own, as the nucleus is; others, such as the ribosome, are not.
polysomeSeveral ribosomes working along one RNA strand. Its longer name is polyribosome. The ribosomes sit along the RNA like beads on a thread.
secretionA cell sending out a substance it has made. Proteins bound for export are packed into vesicles. A vesicle fuses with the cell membrane and empties what it carries outside the cell.
secretory pathwayThe route from ER to Golgi to the cell surface. Proteins that fold properly in the ER travel in vesicles to the Golgi apparatus, are altered there, and move on in secretory vesicles.
symbiogenesisThe theory that some organelles began as bacteria. Also called the endosymbiotic theory. It holds that mitochondria and chloroplasts descend from free-living prokaryotes that were taken into another cell.
ultrastructureDetail too fine for a light microscope to show. It is traditionally viewed with a transmission electron microscope. Organelles can be examined at this level.
Rarer organelles 12
autophagosomeA double-walled ball that hauls cargo to a lysosome. Its outer membrane fuses with the lysosome. The enzymes there break down the cargo and the inner membrane with it.
carboxysomeAn enzyme-filled protein shell in some bacteria. It has no membrane. It concentrates carbon dioxide around the enzyme that fixes carbon, and it was first seen in a cyanobacterium in 1956.
cnidocystAn organelle that shoots out a stinging thread. Jellyfish, corals and sea anemones have it. The thread is a hollow, coiled tube inside a capsule, and it shoots out when a hair-like trigger on the cell is set off.
elaioplastA colorless plastid that makes and stores oils. It is one of the three forms of leucoplast. Elaioplasts are found in the anthers of many flowering plants.
glyoxysomeTurns stored fat into sugar in a sprouting seed. A special kind of peroxisome, found in the fat-storing tissue of seeds such as sunflower, peanut and pumpkin. The seedling lives on the sugar until it can photosynthesize.
hydrogenosomeMakes ATP without oxygen and gives off hydrogen. Found in some one-celled organisms and fungi that live where there is no oxygen. It is thought to have evolved from the mitochondrion, and it was discovered in 1973.
magnetosomeA magnetic crystal in a membrane, inside a bacterium. Magnetosomes line up in a chain that acts like a compass needle, turning the bacterium to follow Earth's magnetic field.
melanosomeWhere animal cells make and store dark pigment. The pigment is melanin, which absorbs light and is commoner in animals than any other pigment of the kind. Melanosomes are made in cells of the skin and of the eye.
phagosomeA sac formed around a particle the cell has engulfed. It goes on to fuse with lysosomes, whose enzymes digest what is inside. Useful products, such as amino acids, pass into the rest of the cell.
proplastidA young plastid, not yet any one kind. All plastids come from proplastids, which are found in the growing regions of a plant. They divide by splitting in two.
proteasomeA hollow complex that shreds proteins marked for it. Cells with a nucleus have proteasomes in the nucleus and in the cytoplasm. Proteins are marked for it with a small tag protein, ubiquitin.
pyrenoidA carbon-fixing center inside an alga's chloroplast. Many algae have one, and so do the hornworts, alone among land plants. It keeps the carbon dioxide level high around the carbon-fixing enzyme.
How this list was compiled: Term list chosen for this site on 2026-10-16. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Cell nucleus, Ribosome, Mitochondrion, Golgi apparatus, Endoplasmic reticulum (the rough and the smooth kind, flat sacs and tubes), Lysosome (more than 60 enzymes, hundreds to a cell, rarely in plant cells), Vacuole, Chloroplast (one to 100 in a cell), Cell wall, Cell membrane, Cytoplasm (about 80 percent water), Organelle (with and without a membrane, and the organelles of bacteria), Cellular compartment, Secretion (the route from the endoplasmic reticulum through the Golgi apparatus to the cell surface), Glycosylation, Chaperone (protein), Polysome, Autophagy, Cytoplasmic streaming (cells larger than about 0.1 millimeter), Symbiogenesis, Cell fractionation, Differential centrifugation, Ultrastructure, Proteasome, Phagosome, Autophagosome, Melanosome, Glyoxysome, Hydrogenosome (discovered in 1973), Magnetosome, Carboxysome (first seen in 1956), Pyrenoid, Elaioplast, Plastid (for the proplastid) and Cnidocyte (for the cnidocyst). The twelve main organelles were checked a second time against two pages of the U.S. National Institutes of Health: the Talking Glossary of Genomic and Genetic Terms of the National Human Genome Research Institute (https://www.genome.gov/genetics-glossary), entries Organelle, Nucleus, Ribosome, Mitochondria, Golgi Body, Endoplasmic Reticulum (Rough), Endoplasmic Reticulum (Smooth), Lysosome, Vacuole, Cytoplasm and Plasma Membrane (Cell Membrane), which also names the cell wall of plant and bacterial cells; and What is a cell? of MedlinePlus Genetics (https://medlineplus.gov/genetics/understanding/basics/cell/). The glossary has no entry for the chloroplast, which rests on its Wikipedia article alone, as do the terms of the second and third sets. The fact after each meaning is from the same pages. Licence: own work
How it works
This cell organelles worksheet lists the nucleus, ribosome, mitochondrion, Golgi apparatus, rough ER, smooth ER, lysosome, vacuole, chloroplast, cell wall, cell membrane and cytoplasm beside their twelve jobs in mixed order. Its key prints after the sheet.
Read the full guide
A cell organelle vocabulary worksheet in three sets
Set opens on Main organelles. The second set, How they work, has organelle, compartment, secretion, secretory pathway, glycosylation, chaperone, polysome, autophagy, cytoplasmic streaming, symbiogenesis, cell fractionation and ultrastructure.
Rarer organelles
The third set has proteasome, phagosome, autophagosome, melanosome, glyoxysome, hydrogenosome, magnetosome, carboxysome, pyrenoid, elaioplast, proplastid and cnidocyst.
Nucleolus, centriole, cytoskeleton, vesicle and peroxisome are words on the cell word search, not terms here.
Questions and answers
Which organelles do plant cells have that animal cells do not?
The chloroplast and the cell wall. A plant cell also has a vacuole large enough to take up most of its space, while the vacuoles of an animal cell are small.
Which organelles do animal cells have that plant cells do not?
Lysosomes, for the most part: nearly every animal cell has hundreds, and plant cells rarely have any. Centrioles are another. Most cells with a nucleus have them, but those of flowering plants and conifers do not.
Do bacteria have organelles?
Not the ones of plant and animal cells: a bacterium has no nucleus, mitochondria or chloroplasts. It does have ribosomes, and some bacteria have protein shells called carboxysomes or chains of magnetosomes.
Is there a cell organelle matching worksheet with answers?
This is one. On the key, a line joins each organelle to its job, and each of the three sets prints with a key of its own.