Download 4.4 PCR, Electrophoresis, DNA profiling

Genetic Engineering and
Biotechnology Notes
IB Assessment Statement
4.4.1 Outline the use of polymerase chain
reaction (PCR) to copy and amplify
minute quantities of DNA.
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The Tools of Molecular Biology
Scientists use different techniques to:
• make unlimited copies of DNA
• extract DNA from cells
• cut DNA into smaller pieces
• identify the sequence of bases in a DNA
molecule
Using the DNA Sequence
Making Unlimited Copies
• Polymerase chain reaction (PCR) is a
technique that allows biologists to make copies of
genes.
• It is useful when small amounts of DNA are
found
(Example: at a crime scene)
Using the DNA Sequence
DNA is heated to separate its two strands, then
cooled to allow the primers to bind to singlestranded DNA.
DNA polymerase enzyme starts making copies of
the region between the primers.
The DNA Polymerase Enzyme is removed from a
bacteria Thermus aquaticus
Using the DNA Sequence
Polymerase Chain Reaction (PCR)
DNA heated to
separate strands
DNA polymerase adds
complementary strand
DNA fragment
to be copied
PCR cycles 1
DNA copies 1
2
2
3
4
4
8
5 etc.
16 etc.
PCR ANIMATION
http://highered.mcgrawhill.com/olc/dl/120078/micro15.swf
http://www.sumanasinc.com/webcontent/animations/c
ontent/pcr.html
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PCR Virtual Lab – Upload answers on
Moodle
Click here to go to Virtual Lab Website:
http://learn.genetics.utah.edu/content/labs/pcr/
Answer the below questions:
1.What is the overall purpose of PCR?
2.What does the why is a primer, DNA
polymerase, and nucleotides necessary for
the reaction?
3.Why must you lower and raise the
temperature of the reaction?
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IB Assessment
4.4.2 State that, in gel electrophoresis,
fragments of DNA move in an electric
field and are separated according to their
size.
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The Tools of Molecular Biology
DNA Extraction
DNA can be extracted from most cells by a simple
chemical procedure.
The cells are opened and the DNA is separated
from the other cell parts.
The Tools of Molecular Biology
Cutting DNA
Most DNA molecules are too large to be analyzed,
so biologists cut them into smaller fragments
using restriction enzymes.
The Tools of Molecular Biology
Each restriction enzyme cuts DNA at a specific
sequence of nucleotides.
Recognition sequences
DNA sequence
Restriction enzyme EcoR I cuts
the DNA into fragments
Sticky end
The Tools of Molecular Biology
A restriction enzyme will cut a DNA sequence only if
it matches the sequence precisely.
Recognition sequences
DNA sequence
Restriction enzyme EcoR I cuts
the DNA into fragments
Sticky end
The Tools of Molecular Biology
Separating DNA
In gel electrophoresis, DNA fragments are placed
at one end of a porous gel, and an electric
voltage is applied to the gel.
When the power is turned on, the negativelycharged DNA molecules move toward the
positive end of the gel.
The Tools of Molecular Biology
Gel electrophoresis can be used to compare the
genomes of different organisms or different
individuals.
It can also be used to locate and identify one
particular gene in an individual's genome.
The Tools of Molecular Biology
Power
source
DNA plus restriction
enzyme
Longer
fragments
Mixture of
DNA
fragments
Gel
Gel Electrophoresis
Shorter
fragments
The Tools of Molecular Biology
First, restriction
enzymes cut DNA
into fragments.
DNA plus
restriction enzyme
The DNA fragments
are poured into wells
on a gel.
Mixture of DNA
fragments
Gel Electrophoresis
Gel
The Tools of Molecular Biology
An electric voltage is
applied to the gel.
This moves the DNA
fragments across
the gel.
The smaller the
DNA fragment, the
faster and farther it
will move across the
gel.
Power
source
Gel Electrophoresis
The Tools of Molecular Biology
Based on size, the
DNA fragments make a
pattern of bands on
the gel.
These bands can then
be compared with
other samples of
DNA.
Longer
fragments
Shorter
fragments
Gel Electrophoresis
Gel Electrophoresis Animation
http://www.sumanasinc.com/webcontent/animations/c
ontent/gelelectrophoresis.html
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IB ASSESSMENT STATEMENT
4.4.3 State that gel electrophoresis of DNA is used in
DNA profiling.
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IB Assessment Statement
4.4.4 Describe the application of DNA profiling to
determine paternity and also in forensic
investigations.
4.4.5 Analyse DNA profiles to draw conclusions
about paternity or forensic investigations.
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This DNA fingerprints are used to do DNA
Profiling.
There are two many uses for DNA profiling:
1. Forensic use – determine the guilt of a criminal
2. Paternity Test – determine who the father of an
offspring
IB Assessment Statement
4.4.4 Describe the application of DNA profiling to
determine paternity and also in forensic
investigations.
4.4.5 Analyse DNA profiles to draw conclusions
about paternity or forensic investigations.
Copyright Pearson Prentice Hall
Gel Electrophoresis Lab
Click here to go to the website:
http://learn.genetics.utah.edu/content/labs/gel/
Answer the questions and address the tasksbelow:
1.Summarize the procedure of gel electrophoresis
2.State two properties of the fragmented pieces of DNA which allow
them to be separated in gel electrophoresis.
Copyright Pearson Prentice Hall
This DNA fingerprints are used to do DNA
Profiling.
There are two many uses for DNA profiling:
1. Forensic use – determine the guilt of a
criminal
2. Paternity Test – determine who the father of
an offspring
Paternity Test Animation
http://www.sumanasinc.com/webcontent/an
imations/content/paternitytesting.html
Copyright Pearson Prentice Hall
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Click here to go the website:
http://learn.genetics.utah.edu/archive/mystery/records.html
The Case of the Pot Hunters
Click here to go the website:
http://learn.genetics.utah.edu/archive/mystery/records.html
Then read the prepared evidence , analyze the gel
electrophoresis results, and read the courts transcript, and
you decide whether or not the suspect is guilty.
Write your decision on an MS Word document. Be sure to
clearly state whether you think the suspect is gulity/ not
guilty/ or if there is not enough information to say either
way. Support your statement with scientific evidence and
logical reasoning.
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IB Assessment Statement
Outline three outcomes of the sequencing of the
complete human genome.
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Outline three outcomes of the sequencing of the
complete human genome.
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Human Genome Project
• A project set out to sequence the complete
human genome.
• It hoped to determine all the bases A, T, C, G in
the human DNA.
• In 2003, it succeeded.
• Now scientists are trying to figure out which base
sequence represents genes.
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Human Genome Project:
It can be thought of as a map showing the locus of
any gene on the 23 pairs of chromosomes.
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Benefits of the Human Genome Project:
• Find out if people are carrying a disease causing
allele
• Find beneficial molecules which are produced
naturally by healthy people
• Find out which gene controls the synthesis of a
desirable molecule
• Copy the above gene and use t as instructions to
synthesize the molecule in a laboratory
• Distribute above molecule as a new medical
treatment
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Human Genome
• It is estimated that
humans consist of
25,000-30,000 genes.
• More the 1500 genes
have been identified
that cause disease.
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http://www.youtube.com/watch?v=zi8FfMBYCkk
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Outline three outcomes of the sequencing of the
complete human genome.
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Human Genome Project
Click on the below website and watch the
INTRODUCTION animation. In your own words
explain what the Human Genome Project is:
http://www.genome.gov/25019885
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http://www.hhmi.org/biointeractive/m
edia/DNAi_genetic_eng-sm.mov
http://www.ted.com/talks/lang/en/pau
l_root_wolpe_it_s_time_to_question
_bio_engineering.html