The Endoplasmic Reticulum, Explained

"The Endoplasmic Reticulum"
Michael W. Davidson and The Florida State University, Molecular Expression^TM

"The endoplasmic reticulum (ER) is a network of flattened sacs and branching tubules that extends throughout the cytoplasm in plant and animal cells. These sacs and tubules are all interconnected by a single continuous membrane so that the organelle has only one large, highly convoluted and complexly arranged lumen (internal space). Usually referred to as the endoplasmic reticulum cisternal space, the lumen of the organelle often takes up more than 10 percent of the total volume of a cell...."

There's more - including a colored drawing of the endoplasmic reticulum and part of the nucleus that does a better job than most, of illustrating what the ER is, how it's and how it relates to the rest of the cell. I'd show you, but the copyright statement at the bottom of the page seems to exclude use of images - even for a micro-review like this.

So you'll have to take the Lemming's word for it.

It's a pretty good resource, for learning how this part of cellular machinery works. Here's a sample of how the ER's function is described:

"...These proteins may be either transmembrane proteins, which become embedded in the membrane of the endoplasmic reticulum, or water-soluble proteins, which are able to pass completely through the membrane into the lumen. Those that reach the inside of the endoplasmic reticulum are folded into the correct three-dimensional conformation, as a flattened cardboard box might be opened up and folded into its proper shape in order to become a useful container. Chemicals, such as carbohydrates or sugars, are added, then...."

I've seen educational pages that are a tad easier to read than this one - but the author did, in my opinion, an unusually good job of actually saying something with the big words.