Download amino acids biochemistry unit

Amino Acids and Protein
David Conneely
Brooklyn International High School
Summer Research Program for Science Teachers
August 2008
Subject: Living Environment (Biology)
Note to Teachers
This is a great activity to help students build on the following concepts:
· Proteins are made of amino acids.
· There are many different proteins in our body and they have different functions.
· The order of amino acids determines the type of protein and its function.
Other concepts can be built into this lesson. Prior to this lesson, students would have experienced several lessons on
atoms and molecules, then on monomers and polymers in sugar and starch. Students also would have learned about DNA,
and done a lab on extracting DNA.
In the activity students build protein bracelets using beads with different colors and shapes that represent the different
amino acids. Table I in the activity sheet identifies the different beads. I buy the beads at a bead shop. You may need to
modify Table I in order to match the beads you have. You can email me if you need the Word document for this. One can
also order the beads online. In terms of string, I use the stretchy string to make them. This can also be purchased at a bead
shop. Make sure you buy enough beads and stretch string so each student can make at least one bracelet.
I offer students the chance to make a bracelet and give the bracelet to someone else. The gift tags are on the last page of
the activity sheet. I usually photocopy and cut the gift tags and I have them located in front of the classroom. Students can
come up and get one. They enjoy giving the gift of protein to family and friends. (e.g., Relax, or Health).
Total Time
· One-two class periods
Aim: What are proteins, what is their function, and what are the building blocks of proteins?
Do Now: In some countries, children who do not get enough protein develop large stomachs. Why?
Procedure:
After students complete the Do Now, the teacher can start class by talking about the Do Now and then asking students
questions about prior lessons:
· What is the basic unit of life?
· What is DNA?
· What is it shaped like?
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· Where is DNA located in the cell?
· Why is it located in the nucleus?
· How can you remove the DNA?
· What does soap do to grease?
· What did your DNA look like when you extracted it?
Today we are going to do two things. First we will read an article about a disease caused when people do not get enough
protein in their diet. Then we will do an activity in which we make models of proteins.
Read article by having different students take turns reading. Discuss the article with students. Elicit from students that we
need protein in for structure and regulation of our bodies.
Transition to the activity on making protein bracelets. Ask students, “Remember what makes up starch?” Glucose. Explain
that protein is similar. It is a polymer and it is made up of… monomers. What makes up proteins? These building blocks
are known as amino acids. There are about 20 types of amino acids in the human body. How many different types of
proteins do you think you have? Take different responses. Explain that there are more than 20,000 types of proteins in the
human body. How is this possible? 20 types of amino acids, but more than 20,000 types of proteins? It is possible.
Here is a good example: How many words are there in the English language? How many letters are there? There are only
26 letters but there are over 100,000 words in the English language. Elicit from students how this is possible.
Start by writing the word mad. Can anyone use these letters to make a different word? A student will identify the word
dam. Are there other words that have similar letters? Perhaps write down adam, madam.
Proteins are similar. The order of letters determines the meaning of a word (example: mad versus dam). The order of
amino acids determines the type of protein and its function.
Activity:
Read through the activity sheet (PDF) and complete the activity. Students make anywhere from one or several protein
bracelets. Have students work together and then answer the questions in groups or individually. Review the questions at
the end.
National Science Standards
Life Science, Content Standard C: In all organisms, the instructions for specifying the characteristics of the organism are
carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T).
Most cell functions involve chemical reactions. Food molecules taken into cells react to provide the chemical constituents
needed to synthesize other molecules. Both breakdown and synthesis are made possible by a large set of protein catalysts,
called enzymes.
New York State Science Standards (Living Environment)
1.2h: Many organic and inorganic substances dissolved in cells allow necessary chemical reactions to take place in order to
maintain life. Large organic food molecules such as proteins and starches must initially be broken down (digested to amino
acids and simple sugars respectively), in order to enter cells. Once nutrients enter a cell, the cell will use them as building
blocks in the synthesis of compounds necessary for life.
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2.1g: Cells store and use coded information. The genetic information stored in DNA is used to direct the synthesis of the
thousands of proteins that each cell requires.
2.1i: The work of the cell is carried out by the many different types of molecules it assembles, mostly proteins. Protein
molecules are long, usually folded chains made from 20 different kinds of amino acids in a specific sequence. This
sequence influences the shape of the protein. The shape of the protein, in turn, determines its function.
5.1c: In all organisms, organic compounds can be used to assemble other molecules such as proteins, DNA, starch, and
fats. The chemical energy stored in bonds can be used as a source of energy for life processes.
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