What do all those organelles do?
Protein trafficking in a goblet cell…
Mucus is made and secreted by goblet cells in the epithelial lining of your airways. The
mucus itself is a mixture of water and a substance called mucin. Mucin is an example of a
glyco-protein – in other words, a protein molecule with lots of carbohydrate chains
attached.
It looks a bit like this:
Carbohydrate chains
It’s obviously quite a complicated thing to construct. First the cell has to put all the right amino acids
in the right order to make the core protein – and then the protein has to be folded into the right
shape and have all those carbohydrate chains stuck on. How does it do it?
A:
It uses just about all of the organelles you have learned about!
PLEASE TURN OVER
What to do next…
Open your Chromebook and go to www.johnkyrk.com. Find the animation on the Golgi
Apparatus.
Use the animation, and the descriptors below, to construct an illustrated A3 flow diagram
of the production of mucus. NB: THESE DESCRIPTORS ARE NOT IN THE CORRECT ORDER!
The long chain of amino acids (aka a polypeptide) is folded in the endoplasmic
reticulum to form the mucin protein.
The membrane of the transport vesicle fuses with the cell surface membrane and
the mucus is secreted from the cell.
The mRNA is transported to a ribosome on the rough endoplasmic reticulum.
Transport vesicles containing the finished mucin glyco-protein bud from the far end
of the Golgi apparatus.
The ribosome uses the information on the mRNA to assemble amino acids in the
correct sequence for the mucin protein.
The mRNA copy of the mucin gene moves out of the nucleus through a nuclear pore.
The transport vesicles move along the micro-tubules of the cytoskeleton to the cell
surface membrane.
The gene coding for the mucus protein is copied in the nucleus.
The mucin protein is slowly moved through the compartments of the Golgi
apparatus where the carbohydrate chains are attached.
Transport vesicles move the mucin protein from the ER to the Golgi apparatus.
Question: what do you think the role of the mitochondria is in all this?
Finished? Good. Now check out the animations at
http://learn.genetics.utah.edu/content/cells/vesicles/