Download BACKGROUND INFORMATION:

Unit 11 Lesson 1 Mastery Assignment
Name ____________________________________________
BACKGROUND INFORMATION:
Recombinant DNA refers to DNA of one organism inserted into the DNA of another. The
major tools of recombinant DNA technology are bacterial enzymes called restriction enzymes. Each
enzyme recognizes a short, specific nucleotide sequence in DNA molecules, and cuts the backbones
of the molecules at that sequence. The result is a set of double-stranded DNA fragments with singlestranded ends, called "sticky ends." Sticky ends are not really sticky; however, the bases on the
single stranded ends do easily form base pairs with the complementary bases on other DNA
molecules. Because of this , the sticky ends of DNA fragments can be used to join DNA pieces that
came from different sources.
In order to be useful, the recombinant DNA molecules have to be put into a cell so that they
can be translated into protein. One method for doing this is to use plasmid DNA from bacteria.
Plasmids are small circular pieces of DNA found in bacteria. Genes (DNA fragments) can be placed
into the plasmids. The plasmids are then put back into bacterial cells. As the bacteria reproduce, so
do the recombinant plasmids. The result is a bacterial colony in which the foreign gene has been
cloned.
In 1978 Genentech in South San Francisco used this process to create recombinant insulin known as
rInsulin, or Humulin©. Insulin is a hormone produced by the pancreas used to digest sugars.
Diabetes occurs when the body does not produce enough (or does not properly respond to) insulin.
Because insulin is a protein coded for by a gene, Genentech developed a process of inserting the
gene for insulin into a bacterial plasmid, in turn tricking bacteria into growing large volumes of insulin
for diabetic patients all over the world. This discovery made Genentech one of the first biotech
companies in the world, and one of the biggest and most influential even to this day.
Since Bacteria and genes are too small to be seen, you are going to model the process done
by Genentech using paper, scissors, and tape. Have fun!
Unit 11 Lesson 1 Mastery Assignment
Name ____________________________________________
Materials:
 M11 L1 CA Template Sheet
 Red and Blue Colored Pencils or Crayons
 Scissors
 Tape
 Sharpie
Procedure:
1. Download and print the M11 L1 CA Paper Plasmid Template
2. Color and cut out the two pieces of DNA.
3. Notice that the bacterial DNA is circular, while the human DNA containing the gene to make
insulin is linear.
4. The (restriction) enzyme used cuts the DNA between two Guanine bases in a staggered way
as shown below.
G G-A-T-C-C
C-C-T-A-G G
5. Use a pencil to trace over WHERE the enzyme will cut the HUMAN DNA (BLUE strip of paper
)at both sites as shown below
Use the SCISSORS to cut the DNA fragment along these lines. Be careful when using
scissors. Notice that the DNA now has unmatched bases exposed. These are called “sticky
ends” because they can base pair with new matching DNA.
You now have a DNA fragment containing a gene that can be inserted into the plasmid.
6. Once the sequence containing the gene has been cut out, cut the plasmid (ring of DNA) in the
same way. Trace the lines you will cut before you actually cut them.
7. Splice the gene into the plasmid by taping the paper strips together where the “sticky ends”
pair properly (REMEMBER complimentary base pairing rules). The tape does the job of
another enzyme called ligase . Ligase is used to rejoin the two pieces of DNA.
The new plasmid (the plasmid containing the new GENE) represents the recombinant DNA.
Unit 11 Lesson 1 Mastery Assignment
Name ____________________________________________
Questions:
1. This lab used paper, scissors, and tape to model what is done in a lab. Match the materials
YOU used with what they represent.
2. Use the following words:
Red paper ring
Blue strip of paper
Scissors
Tape
a. Bacterial Plasmid DNA ____________________________
b. Human DNA ______________________________________
c. (restriction) enzymes ________________________________
d. Ligase _____________________________________________
3. Why were you able to join the two pieces of DNA (think about complementary base pairs)
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4. Why is the new DNA formed called RECOMBINANT DNA?
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5. What would have happened if you used an enzyme that cut the plasmid in two places?
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6. How do you think this process is important in our everyday life?
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7. How else could this process be used?
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