Rough endoplasmic reticulumWhere the proteins are made, by the ribosomes on its surface. Vesicles then carry them to the Golgi.
Transport vesicleA small bubble of membrane that buds from the ER. It carries proteins and lipids to the cis face.
Cis faceThe side of the Golgi closer to the ER. Transport vesicles fuse with it and empty their contents in.
CisternaeThe flattened membrane sacs that make up the stack. The cargo is modified, mostly by adding sugar chains, as it moves through them.
Trans faceThe side of the Golgi away from the ER. The finished proteins are packed into vesicles here.
Secretory vesicleA vesicle that buds from the trans face. Some carry their contents to other parts of the cell; others fuse with the plasma membrane and release them outside.
Plasma membraneThe cell's outer membrane. A secretory vesicle fuses with it to release its contents outside the cell.
The stack: 4 1
LumenThe space inside a cisterna. The cargo sits here while it is processed.
In and out: 5 1
LysosomeA sac of digestive enzymes that breaks down worn-out parts and invaders. It is made with the help of the Golgi.
How this list was compiled: Read 2026-09-26. OpenStax Biology 2e, section 4.4 The Endomembrane System and Proteins, https://openstax.org/books/biology-2e/pages/4-4-the-endomembrane-system-and-proteins : the Golgi apparatus (Golgi body) as a series of flattened membranous sacs; the side closer to the ER the cis face, the opposite side the trans face; transport vesicles from the ER fusing with the cis face and emptying into the lumen; modification by adding short sugar chains, then tagging; secretory vesicles budding from the trans face, some delivering to other cell parts and some fusing with the plasma membrane to release their contents outside the cell; lysosomes as part of the endomembrane system with hydrolytic enzymes. Wikipedia, Golgi apparatus, https://en.wikipedia.org/wiki/Golgi_apparatus : the flattened membrane-enclosed disks called cisternae, usually four to eight in a stack; cis, medial and trans compartments, the cis Golgi network and the trans Golgi network, the TGN packaging proteins into vesicles destined to lysosomes, secretory vesicles or the cell surface. Licence: own work
The drawing: Drawn for this site by script, 2026-09-26. Own work, nothing traced. Licence: own work
How it works
A Golgi apparatus diagram labeled along the route proteins take: from the rough ER, by transport vesicle to the cis face, through the cisternae, and out of the trans face in secretory vesicles. Start with the 7 main parts.
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In at the cis face
Transport vesicles bud from the ER, travel to the cis face, fuse with it and empty their proteins and lipids into the lumen. The cis face is the side nearer the ER.
Out at the trans face
Moving through the cisternae, the proteins are modified, mostly by adding sugar chains, and tagged. The trans face packs them into secretory vesicles, which go to other parts of the cell or fuse with the plasma membrane and release them outside.
Cis faces the ER, trans faces away: cis comes in, trans goes out.
Questions and answers
What does the Golgi apparatus do?
It sorts, modifies, tags and packages proteins and lipids made in the ER, then sends them on in vesicles to where they are needed, including out of the cell.
What is the difference between the cis face and the trans face?
The cis face is the side nearer the ER, where transport vesicles arrive. The trans face is the opposite side, where finished proteins leave in secretory vesicles.
What are cisternae?
The flattened membrane sacs stacked to make the Golgi, usually four to eight in a stack. The space inside each one is its lumen.