Protein Synthesis

To continue your learning about protein synthesis, go to http://www.lewport.wnyric.org/jwanamaker/animations/Protein Synthesis - long.swf and answer the following questions.

1. What is Protein Synthesis?

 

2. What two things do cells use proteins for?

 

3. What do genes do?

 

4. What does DNA have to do to start protein synthesis?

 

5. Describe how messenger RNA forms

 

6. Where does mRNA go?

 

7. How is the structure of mRNA similar to the structure of a protein?

 

8. How many subunits (bases) code for each amino acid?

 

9. Amino acids are attached to a small piece of  Transfer RNA (tRNA). Describe how tRNA works with the ribosome to put amino acids in the proper order.

 

10. What is a polypeptide? Why is it called this?

 

11. What is the difference between a polypeptide and a protein?

 

12. What happens to the growing polypeptide?

 

13. Why is this important?

 

 

Close the window that the link opened, then go here: http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html click on "Protein Synthesis", click on "unzip" and go through the instructions to assemble a polypetide.

After each step, look for the "ok" button to continue.

You will assemble a messenger RNA segment by dragging the complementary bases into position.

Then you get to drag amino acids to assemble the polypeptide.

 

14: List the amino acids you assembled in order here:

 

Once you assembled your short polypeptide, go to: http://www.pbs.org/wgbh/aso/tryit/dna/protein.html and read about hair to answer the following questions.

15. How do hair follicle cells make the protein keratin?

 

 

16. How long can it take to assemble a 400 amino acid chain?

 

 

The End

Text from http://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synthesis%20-%20long.swf

Cell Nucleus Chromosomes © 2001 J.R. Wanamaker Ribosomes Protein Synthesis is the making of proteins, using the information that is found in DNA (chromosomes). Proteins are very important molecules for a cell. Proteins are used to build cell structures and are used as enzymes Proteins are long chains of small molecules called amino acids. Different proteins are made by using different sequences of amino acids. The pieces of information in DNA are called genes . Genes describe how to make proteins by putting the correct amino acids into a long chain in the correct order. Piece of DNA selected for study We will focus in on one small piece of DNA to look at one small gene. We will then see how the information of DNA is converted to a protein's amino acid sequence. Let's zoom in on this short segment of DNA to see how its information is used. Protein synthesis begins with the stored genetic information of a DNA molecule. The DNA of this gene will "unzip" like the DNA does during replication. Only one side of the DNA is used now. (Both sides are used for DNA replication, to copy the chromosome.) Gene (information) Unused strand A single-strand of RNA forms, one subunit at a time, and transcribes (copies) the genetic information from the DNA. RNA subunit The new strand is an RNA molecule. Note that there is one difference in the subunits: RNA contains Purple instead of Blue ( U instead of T). The RNA now has copied the subunit sequence of the gene. The DNA is no longer needed in the process of protein synthesis. The DNA "zips" closed and remains in the nucleus. DNA double strand This RNA molecule is called messenger RNA (now carrying the genetic "message"). It will leave the nucleus and travel to a ribosome to build a protein molecule. Messenger RNA (or mRNA ) Let's zoom back out to see how this process is occurring in the cell. Here, you can see the RNA inside the nucleus of the cell. The RNA was formed in the nucleus to get gene information from the chromosomes. mRNA that we saw being formed You can see the chromosomes here in the nucleus. Remember, the never leave the Chromosomes (DNA) The molecule of RNA, however, will leave the nucleus and travel to a ribosome. Ribosomes are the cell parts that make proteins. Once the mRNA is at the ribosome, the genetic information will be translated by the ribosome to make a protein. We will now zoom in to the ribosome to see how the genetic information is interpreted and used to assemble the protein. Remember, the mRNA is a sequence of subunits (like chain ) that tells how to build a protein. A protein is a ­ a amino acids. Code for one amino acid The messenger RNA contains information in sets of three subunits. Each set of three is the code for a particular amino acid. The information of the messenger RNA (mRNA) describes which amino acids should be in the protein chain. A molecule of transfer RNA (tRNA) will carry in the proper amino acid, one at a time. tRNA Amino acid The tRNA matches up to the mRNA, just like the two strands of a DNA molecule match up. The sequence of three subunits of the mRNA can only match up with one particular tRNA. Two different amino acids Two different tRNA molecules A different set of three mRNA subunits means a different tRNA molecule. That means a different amino acid will be carried in. The two amino acids are linked by a peptide bond. Then a tRNA molecule leaves the ribosome. Peptide bond The next tRNA will carry in the proper amino acid, and the process will continue as the amino acids are linked into a chain. The chain of amino acids is called a " polypeptide ," and when it is very long, it is called a protein ." A protein would never have just three amino acids, like we have pictured here. Let's speed up the process to watch the polypeptide chain form. Amino acids As the long chain forms, watch how the sequence of amino acids determines the shape of the protein. Beginning of a polypeptide chain. Even this is a very short polypeptide chain. Most have hundreds or thousands of amino acids. Short polypeptide chain, or part of a protein. The shape that the chain forms is very important, because the shape of a protein determines how it functions. If a different sequence of amino acids is used, the protein chain would have a different shape, and therefore a different function. The protein can now be used to form structures, or be used as an enzyme to speed up cell reactions.

Text version of http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html can be found at: http://www.pbs.org/wgbh/aso/tryit/dna/indextdna.html