Chapter 2.2.1: The Endoplasmic Reticulum

The Endoplasmic Reticulum (ER) is a very amazing part of the cell! (Well I
guess every part of the cell is amazing if you see all of what it does).
It is responsible for a wide range of tasks! Including the biosynthesis of:
lipids for constructing new membranes, proteins (via ribosomes) and complex
carbohydrates. The ER membrane typically makes up more than half of the total
membrane in the cell and is located between the nucleus and the cytosol and
specifically the golgi apparatus.
This means
that there is 2 membranes between the nucleus and the Golgi Apparatus, the
outside ER membrane and the nuclear membrane (This is because the ER is
continuous with the outer nuclear membrane). However, there are 2 membranes
between the golgi and the ER and there is a LARGE amount of transfer between
the two organelles, which suggests there is probably transport occurring through
transport vesicles (shown below).

The ER is a made up of two phospholipid bilayer membranes.
The enclosed 'sac' is called the ER lumen, the internal space of the ER. The
ER is thought to be a single continuous membrane (Reference). Also there are two types of ER:

Rough ER: Is associated with ribosomes (the dots on its boundaries)
and the membranes tend to be in 'sheets' or flatten sacs called
cisternae.

Smooth ER: Which lacks ribosomes, and is also more of a mesh of
smaller interconnecting tubes.

The Endoplasmic Reticulum:

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Please send questions/comments/suggestions to: Mark Dalton at markwdalton@gmail.com.