Download Receptor Protein

Receptor Protein
Receptor proteins are proteins imbedded in the cell membrane (Check out
the picture below). These proteins span across the membrane, so part of it is
sticking out of the cell and part of it is inside of the cell. These receptor
proteins, like the transport proteins we learned about earlier, are specific so
they only work with certain substances. A receptor protein is meant to
recognize and bind to specific substances outside of the cell. They, meaning
the substance and the receptor protein, fit together like a lock and key, a
game boy cartridge and a game boy or a hand in a glove (if none of these
analogies make sense just ask or try to think of your own).
Once a receptor protein binds with a substance or what we will now call a
chemical signal, it then sends a chemical messenger into the cell. In other
words, the receptor protein received a message (chemical signal) and is now
sending a message into the cell.
A diagram of a receptor protein receiving a chemical signal and then sending a chemical
messenger into the cell.
Nucleus
The Nucleus is a large membrane-bound organelle that stores information in
the form of DNA (deoxyribonucleic acid). Surrounding the nucleus is a
special membrane known as the nuclear envelope. Since the nuclear
envelope is actually made of two membranes, there are parts in it where the
two membranes are fused together to form circular openings known as
nuclear pores. Messages are able to get into and out of the nucleus through
these pores. Incoming messages can affect what messages the nucleus sends
out.
A nucleus sends out messages to other parts of the cell in the form of mRNA
(messenger ribonucleic acid) [Label the arrow leaving the nucleus as mRNA
on the diagram below]. These mRNAs are used as a way to send the
information stored in the DNA of the nucleus, to places in the cell that make
proteins. The mRNA has the directions that tell the ribosomes (the place that
makes the proteins) how to make a specific protein.
A diagram of a nucleus located inside of a cell.
Endoplasmic Reticulum and Ribosomes
The endoplasmic reticulum is a network of enclosed space inside of a cell
made of internal membrane. Remember how the cell membrane of a cell
separates the cell from the outside environment? The endoplasmic reticulum
has a similar function except it separates itself from the cytosol inside of the
cell. Part of the “ER” is known as the rough endoplasmic reticulum because
it has ribosomes attached to its membrane.
Ribosomes are the protein factories of the cells. They receive directions in
the form of mRNA (messenger ribonucleic acid) that tell it how to make a
specific protein. Since the ribosome is attached to the ER, the message is
received on the outside of the ER and then the protein is made on the inside
of the ER.
A picture of the endoplasmic reticulum. Keep in mind that this is a cross
section so it has a slice through it to show the inside. Normally it would be
completely enclosed.
Golgi Apparatus
The golgi apparatus is a set of membrane-bound sacs located near the
nucleus of a cell. After receiving proteins from the endoplasmic reticulum,
the main function of the golgi apparatus is to sort and process proteins. What
this means is that “the golgi” modifies the proteins it receives so they can be
sorted into the right vesicle.
A vesicle is a small membrane bound sac that is used to transport certain
substances. In this case, the golgi apparatus sorted a variety of proteins and
placed them into the appropriate vesicle. Once the vesicles have been packed
they are released and they either go to other cell organelles or they travel to
the cell membrane where they release its contents (the proteins).
A representation of the Golgi Appartus. The lumen refers to the hollow space
inside of the Golgi. The membrane bound vesicles are what are carrying the
substances to the appropriate places.
Protein Pathway
1. Discussion protocol: The first thing your group will do after you have
each individually finished reading your article is go around to each group
member and one at a time explain (through speaking, writing and/or
drawing) what you read about to the rest of your group. While your group
member is explaining what he or she read about, he or she deserves your
undivided attention, so listen close.
2. Once all group members have shared what they read about, if there are
parts from any of the readings that are confusing for anyone in your group.
Help each other make sense of the article by re-explaining or asking
questions.
3. If your group feels that you now have a grasp on all four articles, put the
different parts of the pathway in order. There is a sequence to all of your
articles and make sure to check with a teacher to see if your order is correct.
4. On the back of your article paper, map the process of the four articles out
in the context of the following situation… You just ate a piece of meat (if
you’re a vegetarian then it was some peanuts) and it has now entered your
stomach. At this point your body sent a signal to your “Chief Cells” located
in the gastric pits of your stomach. These “Chief Cells” need to produce
pepsin, an enzyme, to break apart the protein you just ate.
NOTE: When I say map it out, draw and label the process
a. How did your body go about producing the enzyme?
b. What were the cell organelles involved?
5. Remember from our last unit that proteins are made from amino acids.
Where do you think the ribosomes are getting the amino acids from to build
these proteins? How do you know?
6.The ideas from these articles are not limited to only the chief cells in your
stomach. Where else in your body do you think this process is happening
(it’s happening everywhere), but more specifically, think about where else
are there digestive enzymes being made? (Add these ideas to your model)