Question

1. the endoplasmic reticulum (er) makes up more than half the total membrane system in many eukaryotic cells. use this sketch to label and explain the lumen, transport vesicles, and the difference between smooth and rough er.

Explanation:

1. Lumen: The lumen is the internal space within the endoplasmic reticulum. It is a continuous compartment where various biochemical reactions occur, such as protein and lipid modification.
2. Transport Vesicles: These are small membrane - bound sacs that bud off from the endoplasmic reticulum. They carry proteins and lipids synthesized in the ER to other parts of the cell, like the Golgi apparatus.
3. Difference between Smooth and Rough ER: The rough endoplasmic reticulum (RER) has ribosomes attached to its surface, which are involved in protein synthesis. The smooth endoplasmic reticulum (SER) lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium ion storage.

Answer:

Lumen: Internal space of ER for biochemical reactions.
Transport Vesicles: Membrane - bound sacs for transporting ER - synthesized materials.
Smooth ER: No ribosomes, for lipid synthesis etc. Rough ER: Has ribosomes, for protein synthesis.