3D model of an animal cell cut open to show the nucleus, mitochondria, Golgi apparatus and endoplasmic reticulum
Cell type
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This cell 3D model shows two cells you can turn, cut open and click: an animal cell, which is a eukaryotic cell, and an E. coli bacterium, which is a prokaryotic cell. Click any organelle for its name, size and job, or switch to Compare to see both cells at true relative scale.

How to use the cell model

The model opens on the animal cell with a wedge cut out, so you see the organelles inside. Drag to rotate, scroll to zoom and click any part to open its card. The camera flies to the part and the other parts fade back.

Parts of an animal cell and what they do

An animal cell is a eukaryotic cell. Its DNA sits inside a nucleus, and its work is divided among membrane-bound organelles. An animal cell has no cell wall and no chloroplasts, so the plasma membrane is its outer edge. A flat animal cell diagram shows each organelle in a different color. The 3D model shows how they sit around and inside each other.

Each organelle name below is a link that opens its card in the model.

OrganelleWhat it doesSize
Plasma membraneSeparates the cell from its surroundings and controls what passes5 to 10 nm thick
CytoplasmJelly-like fluid that holds the organelles; 70 to 80 percent water10 to 100 µm across
NucleusStores the DNA and directs protein synthesis5 to 10 µm across
NucleolusAssembles ribosome subunits1.8 µm across
Nuclear poreControls traffic between the nucleus and the cytoplasm97 to 120 nm across
RibosomeReads messenger RNA and builds proteins20 to 30 nm across
Rough ERMakes and folds proteins for membranes and export60 to 100 nm thick
Smooth ERMakes lipids, detoxifies chemicals and stores calcium60 to 100 nm across
Golgi apparatusModifies, sorts and ships proteins0.7 to 1.1 µm across
VesicleCarries cargo between organelles30 to 80 nm across
MitochondrionMakes ATP from food molecules0.5 to 2 µm long
LysosomeDigests waste and worn-out cell parts0.1 to 1.2 µm across
PeroxisomeBreaks down fatty acids and handles hydrogen peroxide0.1 to 1 µm across
CentrosomeOrganizes the microtubules0.2 to 0.5 µm
MicrotubuleHollow track for vesicles; holds shape23 to 25 nm across
Actin filamentThin fibre that shapes the cell surface and lets cells move7 nm across
Intermediate filamentRope-like fibre that bears tension8 to 10 nm across
MicrovilliFold the membrane to add surface for absorbing nutrients1 to 6 µm long

Mitochondria: the powerhouse of the cell

Mitochondria are oval organelles with two membranes. The outer membrane forms the boundary. The inner membrane folds into shelves called cristae, and the space those folds enclose is the matrix. In the model the cristae show through the cut. A typical mitochondrion is about 0.5 µm across and up to 2 µm long.

Mitochondria make ATP, the molecule a cell spends as energy. That is why textbooks call them the powerhouse of the cell. The folds matter because the ATP-making machinery sits on the inner membrane, and more folds mean more room for it.

Cells that burn a lot of energy carry a lot of mitochondria. A rat liver cell holds about 1,665 of them, and together they fill about 22 percent of the cell’s volume. A HeLa cell has 383 to 882. Mitochondria also keep a small amount of their own DNA, a remnant of their origin as free-living bacteria that moved into a larger cell.

The cell membrane (plasma membrane)

The cell membrane is a phospholipid bilayer with proteins embedded in it. Two layers of lipid make a sheet only 5 to 10 nm thick. A red blood cell’s membrane is about 7.5 nm thick, around 1/1,000 of the cell’s 8 µm width.

The membrane controls what enters and leaves. Nutrients come in, waste goes out and signals arrive. The embedded proteins work as channels, pumps and receptors, and the lipid bilayer blocks most other traffic. Select the membrane in the model and the other parts dim so you can see the boundary as one continuous surface. The finger-like microvilli are folds of this same membrane.

Every cell has a plasma membrane, including bacteria. In E. coli it is the inner membrane of a two-membrane envelope, and it carries out jobs that mitochondria do in your cells. For how membranes move molecules, see types of membrane transport and types of membrane proteins.

Golgi apparatus

The Golgi apparatus is a stack of flattened membrane sacs called cisternae. In mammalian cells a stack holds 4 to 11 cisternae, and each is 0.7 to 1.1 µm across but only 10 to 20 nm thick at its center.

The Golgi is the cell’s sorting and shipping center. Vesicles from the endoplasmic reticulum arrive at the receiving side, the cis face. The Golgi modifies the proteins, adding sugar chains and phosphate tags that work as destination labels. The shipping side, the trans face, then releases them in secretory vesicles. In plant cells the Golgi also makes the polysaccharides of the cell wall.

Watch the vesicles in the model. They bud from the Golgi and travel along microtubules toward the plasma membrane. Each microtubule is about 25 nm across.

Endoplasmic reticulum: rough and smooth

The endoplasmic reticulum (ER) is a network of membrane sheets and tubes joined to the nuclear envelope. It comes in two kinds, and the model colors them differently.

The rough ER is studded with ribosomes on its outer surface. Those ribosomes make proteins and feed them into the ER lumen, where the proteins fold and pick up side chains. The rough ER also makes phospholipids for the cell’s membranes. It is abundant in protein-secreting cells such as liver cells. Its sheets are about 60 to 100 nm thick.

The smooth ER has no ribosomes. Its tubes, also about 60 to 100 nm across, make carbohydrates, lipids and steroid hormones, detoxify medications and poisons, and store calcium ions. In muscle cells a specialized form stores the calcium that triggers contraction.

Nucleus, ribosomes and the cytoskeleton

The nucleus is a double-membrane compartment, 5 to 10 µm across in a mammalian cell. It holds about 2 m of DNA, packed with proteins as chromatin. RNA copies of genes leave through about 2,000 nuclear pores, and the nucleolus inside assembles ribosome subunits. For the molecule itself, open the DNA 3D model.

The cytoskeleton has three fibres. Actin is the thinnest at 7 nm. Intermediate filaments measure 8 to 10 nm and bear tension. Microtubules are the widest at about 25 nm. A centrosome, built around two centrioles, organizes the microtubules in animal cells.

Eukaryotic cell vs prokaryotic cell

A eukaryotic cell keeps its DNA in a nucleus and has membrane-bound organelles. Animals, plants, fungi and protists are made of eukaryotic cells. A prokaryotic cell has no nucleus and no membrane-bound organelles. Bacteria and archaea are prokaryotes. Both kinds of cell share four parts: a plasma membrane, cytoplasm, DNA and ribosomes.

FeatureAnimal cell (eukaryote)E. coli (prokaryote)
NucleusYes, inside a double-membrane envelopeNo. DNA lies in a nucleoid
Size10 to 100 µm across1 to 3 µm
Ribosomes80S70S
Membrane-bound organellesManyNone
DNALinear chromosomesOne circular chromosome, plus plasmids
Cell wallNonePeptidoglycan wall and an outer membrane
Makes ATP inMitochondriaThe plasma membrane
DivisionMitosisBinary fission

The size gap is large. A HeLa cell is about 17 µm across, so eight or nine E. coli laid end to end would span it. Turn on Compare to see that ratio, then switch on the magnify option to enlarge the bacterium ten times. The ribosomes also differ in type: bacterial 70S ribosomes are lighter than eukaryotic 80S ribosomes, which is why many antibiotics block bacterial ribosomes and leave yours alone.

More on each group: eukaryotic cells, prokaryotic cells and plant cells vs animal cells.

Prokaryotic cell structure: the E. coli bacterium

Escherichia coli is a rod-shaped, gram-negative bacterium about 1 µm wide and 2 to 3 µm long. Everything happens in one compartment, so the model needs fewer parts than the animal cell. Work from the outside in:

For other organisms in this group, see examples of archaea and types of bacterial reproduction.

What the model simplifies

The model is accurate in structure and exaggerated in scale, so that you can see and click every part.

The structure-level facts, such as which membranes surround which parts, follow standard textbook biology. Every size on the cards comes from the sources listed at the end of this page.

Frequently asked questions

What is the difference between prokaryotic and eukaryotic cells?

A eukaryotic cell has a nucleus and membrane-bound organelles. A prokaryotic cell has neither: its DNA lies in a nucleoid and its chemistry runs in a single compartment. Eukaryotic cells are also larger, typically 10 to 100 µm across against 0.1 to 5 µm for prokaryotes, and they have 80S ribosomes where prokaryotes have 70S.

Do bacteria have mitochondria?

No. Bacteria are prokaryotes and have no membrane-bound organelles. They make ATP at their plasma membrane. Mitochondria are thought to descend from bacteria that once lived inside a larger cell.

Why are mitochondria called the powerhouse of the cell?

Mitochondria make most of the ATP that a cell spends as energy. The folds of the inner membrane give the ATP-making machinery a large surface, and energy-hungry cells such as liver cells carry well over a thousand mitochondria.

What organelles do animal cells lack compared with plant cells?

Animal cells have no cell wall, no chloroplasts and no large central vacuole. Animal cells have two things that most plant cells lack: a centrosome with centrioles, and lysosomes. Plant cells do their digesting in vacuoles.

How big is a cell?

Eukaryotic cells are 10 to 100 µm across. A human red blood cell is about 8 µm, and a HeLa cell is about 17 µm. Prokaryotes are 0.1 to 5 µm, and E. coli is about 2 µm long and 1 µm wide.

What is the cell membrane made of?

A phospholipid bilayer with embedded proteins. The two lipid layers are about 5 to 10 nm thick in total.

Is the 3D cell model to scale?

Not exactly. The organelles are in correct proportion to each other within a cell, but thin structures such as membranes and filaments are drawn thicker than true scale. Compare mode shows the true size ratio between the two cells.

Sources

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