Genetic Engineering Simulation

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10 Δεκ 2012 (πριν από 4 χρόνια και 6 μήνες)

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Genetic Engineering Simulation


Name _____________________________

Living Environment

1


Genetic engineering has greatly increased the potential for developing new medicines. Genetic
engineering is the process of removing a gene from one organism and putting it into another.
Sometimes, genes are put into a plant or an animal, such as a human.

One of the first genetic engineering advances involved the hormone insulin. Diabetes is a
medical condition that affects millions of people. Diabetes may involve a destruction of the cells
in the pancreas that produce insulin. As a consequence, this pre
vents the cells from taking in
glucose sugar from the body needed for cell respiration. The disease often results in many
medical complications; including heart attacks, stroke, blindness, and amputations.

Until the 1980s, all insulin was extracted from
the pancreases of animals; such as cattle and pigs.
The sequence of amino acids making up the insulin protein is slightly different in these species in
comparison to human insulin. This insulin was more expensive than insulin today, because it
was limited

in quantity. In addition, this insulin was slightly different and therefore not as
effective as human insulin; moreover, some diabetics had what amounted to an allergic reaction
to the foreign protein.

In 1978, using recombinant DNA techniques, scientist
s synthesized human insulin from the E
coli bacteria. This technique involved inserting the gene
coding for the production of

human
insulin into a common bacterium called E. coli. The gene was cut from a human gene sequence
using
restriction enzymes
, and

the circular piece of bacterial DNA

called a
plasmid

is cut in a
similar way by
restriction enzymes

as well.

Restriction enzymes evolved in bacteria as a way
to defend the bacteria against invading viruses. These enzymes cut the viral DNA into shreds
so the viruses are unable to live or reproduce inside the bacteria.


Once the plasmid is cut, the gene coding
for human insulin is spliced into the plasmid using
another enzyme called
ligase
. When this bacterium was then grown in cultures, it produced va
st
quantities of human insulin which could be isolated fairly easily in pure form, for use by
diabetics. It produced no allergic reactions, because the insulin produced by the bacteria was
human insulin that the human insulin gene directed the bacteria to

produce.

T
he human insulin
was much cheaper when produced in this way than was the insulin from cows, as it could be
produced much more quickly in greater quantity.

Genetic engineering has now produced an enormous variety of drugs and hormones for medica
l
use. Interferon, which is used to eliminate certain viruses and kill cancer cells, also is a product
of genetic engineering, as is human growth hormone. This compound is used to treat dwarfism
and is produced through genetically engineered bacteria and

yeasts.

The relatively new field of
gene therapy

involves manipulating human genes to treat or cure
genetic diseases and disorders. Modified plasmids or viruses often are the messengers to deliver
genetic material to the body's cells, resulting in the pro
duction of substances that should correct
the illness. People with cystic fibrosis inherit defective genetic information and cannot produce
normal CFTR proteins. Scientists have used gene therapy to insert normal DNA segments that
code

for the missing CFTR

protein into the lung cells

of people with cystic fibrosis.

Genetic Engineering Simulation


Name _____________________________

Living Environment

2



In this exercise you will use paper to simulate the genetic engineering of the human insulin gene
in a bacterial plasmid. These diagrams are on the last page of this activity to be easily re
moved
and manipulated.

1. From the
sheet at the end of this activity
, cut out the
bacterial plasmid

DNA
base sequence


in a long strip.

2. As bacterial DNA is packaged in a circular arrangement unlike human DNA, you will need to


take your
cut sec
tion

of bacterial plasmid, form it into a loop with the bases facing outside and


tape the ends together.


3. Now cut out the human DNA
base sequence f
rom the shaded strip. Leave it as a straight strip.



(This is a

fragment from a complex organ
ism, so it is not circular, as it would be packaged in


a chromosome in the nucleus.)


Genetic Engineering Simulation


Name _____________________________

Living Environment

3


4. Now you will simulate the action of a restriction enzyme.
Your restriction enzyme will cut


between the sequence CCGG as indicated in the diagram below.

Restriction enzymes act


as “
molecular scissors” to cut the DNA at
specific

sequences
.

These were first discovered in


bacteria as a defense to cut up the nucleic acids of invading viruses.



a.) Use your restriction enzyme to make the cu
t indicated above in your paper bacterial plasmid.


You should only make one cut.

It should similar to the diagram below.



b.) Now use your restriction enzyme to cut out the simulated gene coding for human insulin in


your human DNA se
quence. If you do this correctly, you should cut out a 12 base


pair section

of DNA and make 2 cuts in your human DNA sequence.


5. Now you will incorporate the human insulin gene into your bacterial plasmid. Attach the ends


of the 12 b
ase human insulin simulated gene to the cut ends of your bacterial plasmid. In a


real genetic engineering experiment, the enzyme DNA ligase would act as this


“molecular glue”,

you

will use small pieces of scotch tape
to do this in our lab.


6. Congratulations! Show your creation to your teacher. If approved, you have successfully


simulated the genetic engineering of a bacterial plasmid able to produce human insulin.


Now


this bacterium will reproduce to make billions of new

bacteria cap
able of producing


human insulin.


Genetic Engineering Simulation


Name _____________________________

Living Environment

4


[Questions]

1. What is the function of restriction enzymes in nature (as used by bacteria)?



______________________________________________________________________


2. What is a bacterial plas
mid?


_________________________________________________________________________


3
. What is the role of restriction enzymes in genetic engineering?


______________________________________________________________________


________________________
_______________________________________________

4
. How did we simulate the function of restriction enzymes in this activity?


_______________________________________________________________________

5
. Identify the enzyme needed to glue pieces of DNA
together in genetic engineering.


________________________________________________

6
. How did we simulate the role of DNA ligase in this activity?


_________________________________________________________________________

7
. Several decades ago
, diabetics did not have access to human insulin. They were


injected with

the insulin of sh
eep or other animals. State two possible
advantage
s

of


using genetic engineering
in the production of
human insulin for diabetics.


_______________
_______________________________________________________________


______________________________________________________________________________


______________________________________________________________________________


________________________
______________________________________________________



Genetic Engineering Simulation


Name _____________________________

Living Environment

5


8. Explain why some diabetics have allergic reactions to insulin which is obtained from


animals other than humans.

_________________________________________________________________________


_________________________________________________________________________


_________________________________________________________________________

9
. Identify two other uses for genetic engineering in addition to the production of human insulin


b
y bacteria.


______________________________________________________________________________


______________________________________________________________________________


________________________________________________________________________
______


______________________________________________________________________________


10. What is gene therapy? List an example of a condition being experimentally treated


by this technique.


___________________________________________
__________________________________


_____________________________________________________________________________


______________________________________________________________________________

Use the diagram below and your knowledge of biology to answer
questions
11

through
1
3
.


Genetic Engineering Simulation


Name _____________________________

Living Environment

6


11
. Identify the substance needed to produce the pictures represented in one and two.



__________________________________________

12
. Identify the enzyme represented by the arrow number three needed to produce the





recombinant DNA plasmid represented following that arrow.



________________________________________

1
3
. Explain why every bacteria which reproduces from the bacterium represented by




the number four will be able to produce human ins
ulin.



_______________________________________________________________________




_______________________________________________________________________


1
4
. Explain why white blood cells would be used to obtain human DNA and not other kinds

of


blood cells.


____________________________________________________________________________


1
5
. Explain why the following statement is incorrect. DNA ligase will provide the


molecular glue to paste human insulin into the bact
erial plasmid.


______________________________________________________________________________


______________________________________________________________________________

Genetic Engineering Simulation


Name _____________________________

Living Environment

7




bacterial plasmid which will reproduce ase
xually


human
DNA sequence

containing simulated
human insulin

gene
coding segment 12 bases in
length


Genetic Engineering Simulation


Name _____________________________

Living Environment

8


Living Environment Core Curriculum

Performance Indicator 2.2
:
Explain how the technology of genetic engineering allows humans
to alt
er genetic makeup of

organisms.

Major Understandings

2.2c Different enzymes can be used to cut, copy, and move segments of DNA. Characteristics
produced by the segments of DNA may be expressed when these segments

are inserted into new
organisms, such as b
acteria.

2.2d Inserting, deleting, or substituting DNA segments can alter genes. An altered gene may be
passed on to every cell that develops from it.

2.2e Knowledge of genetics is making possible new fields of health care; for example, finding
genes which

may have mutations that can cause disease will aid in the development of
preventive measures to fight disease. Substances, such as hormones and enzymes, from
genetically engineered organisms may reduce the cost and side effects of replacing missing body
c
hemicals.

Common Core Standards Addressed

English Language Arts Standards » Science & Technical Subjects » Grades 9
-
10

Key Ideas and Details

-
10.1. Cite specific textual evidence to support analysis of science and technical texts,
attending to the p
recise details of explanations or descriptions.

-
10.2. Determine the central ideas or conclusions of a text; trace the text’s explanation
or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the
text.

-
10.
4. Determine the meaning of symbols, key terms, and other domain
-
specific words
and phrases as they are used in a specific scientific or technical context relevant to grades 9

10
texts and topics.

-
10.5. Analyze the structure of the relationships among concepts in a text, including
relationships among key terms (e.g., force, friction, reaction force, energy).

-
10.7. Translate quantitative or technical information expressed in words in
a text into
visual form (e.g., a table or chart) and translate information expressed visually or mathematically
(e.g., in an equation) into words.

Text Types and Purposes

-
10.1. Write arguments focused on discipline
-
specific content.


WHST.9
-
10.9.

Draw evidence from informational texts to support analysis, reflection, and
research.