dna analysis. take out your review sheet from yesterday. bellringer
TRANSCRIPT
DNA Analysis
Take out your review sheet from yesterday.
Bellringer
Introduction to the characteristics of DNA and DNA analysis.
Objectives
Study your review sheet
Quiz on Friday
DNA “fingerprinting” is a common way to identify people by their unique genetic code
DNA “profiling” is a better way to refer to the process; it has nothing to do with fingers or fingerprints.
DNA
Where can you find DNA?
DNA is in every nucleated cell of the human body and can be extracted from blood, semen, urine, bone, hair follicles, and saliva.
DNA
What types of crimes does DNA evidence help solve?
DNA is currently being used to identify the perpetrator in a crime, to identify fathers in paternity cases, and to identify unknown remains.
DNA
In the nucleus of cells are chromosomes that are inherited from both parents.
Chromosomes are long-chain DNA molecules that are tightly bound in a specific structure.
DNA (deoxyribonucleic acid) is the hereditary material of most organisms. Held together by hydrogen bonds
Aspects of DNA
Chromosomes
Chromosomes
If all of the DNA in your body was stretched out and put end to end, it would reach to the sun and back more than 600 times!
Fun Fact
The human body has approximately 35,000 genes
Genes are simply portions of the DNA that code the information required to make specific proteins.
Proteins determine human traits and functions.
DNA
Each gene has a specific code for a specific body function; they are the fundamental unit of heredity, determining traits from hair color, eye color, and facial features to certain diseases or disorders.
Genes
Began in 1990
Set out to identify all of the genes of humans, and the order they are in.
We did it.
Human Genome Project
The structure of DNA is important to its function.
An unusual property of DNA is its ability to replicate itself.
It is arranged in a right-handed double helix pattern. Twisted ladder
DNA Structure
The sides of the helix are the sugar and phosphates groups (acidic properties)
On the inside are the base pairs. Ladder rungs
The average DNA molecule contains 100 million nucleotide groups.
DNA Structure
The order of these pairs is 99.9 percent the same for everyone.
DNA Structure
Genes are different amounts of base pairs (1,000 to several hundred thousand)
A chromosome is a single DNA molecule twisted and packed into the nucleus of the cell.
The sequence of the nucleotide bases is what determines the proteins that will lead to specific growth, function, and reproduction.
DNA
Identical twins share 100 percent identical DNA.
Fraternal twins share only 50 percent of their DNA, just like regular siblings.
This makes for some twists in crimes!
Twins
How you get your DNA
What are chromosomes?
How is DNA like a fingerprint?
Checkpoint
Read pages 340 to 345 in the textbook and answer the following questions:
1. How and when was the first criminal case to use DNA evidence?
2. What type of blood cell contains DNA?3. How many nuclei are in a single drop of blood?4. Name 4 uses of DNA profiling5. What is used to release DNA from the
chromosome?6. What are the four main procedures involved in
DNA fingerprinting?
Forensic Uses of DNA
1. Blood samples were taken for DNA testing in 1986.
2. White blood cells contain DNA because they have a nucleus.
3. A single drop of blood contains between 7,000 to 25,000 nuclei.
4. Clearing the wrongly accused, identifying victims, establishing family relationships, and identify suspects.
5. Enzymes are used to release DNA from the chromosomes.
6. Isolation, Cutting, Sorting, and Analyzing.
Answers
Where is DNA located in the body?
Bellringer
Learn how forensic scientist extract DNA from a chromosome
Objective
1. Blood samples were taken for DNA testing in 1986.
2. White blood cells contain DNA because they have a nucleus.
3. A single drop of blood contains between 7,000 to 25,000 nuclei.
4. Clearing the wrongly accused, identifying victims, establishing family relationships, and identify suspects.
5. Enzymes are used to release DNA from the chromosomes.
6. Isolation, Cutting, Sorting, and Analyzing.
Answers
The base pairs of DNA only have two possibilities
1. Adenine –Thymine2. Guanine-Cytosine
Written as A,T,G, & C for short.
DNA
The DNA molecule is hundreds of thousands of base pairs long.
Break the DNA molecule at certain points to form fragments. Then compare the size and amount of fragments.
1 in 5 million chance of someone else sharing your profile
Statistical Analysis in DNA Profiling
R-Restriction enzymes are used to cut the DNA into F-Fragments that are many different L=Lengths and exhibit P-Polymorphism, which means many shapes.
The length of these fragments varies greatly among individuals
RFLP Analysis
A DNA sample is placed in a special tank that has an electric charge going across it.
An enzyme is added to the tank the cuts the DNA at specific spots.
The different lengths of DNA then move across the tank at different speeds depending on their length.
RFLP Analysis
RFLP Analysis
1. What are the two possible base pairs of DNA?
2. What does RFLP stand for?
Checkpoint
How does RFLP analysis work, and why is it done?
Bellringer
Finish RFLP testing activity
Know when to use each of the four main DNA analysis techniques.
Objectives
Movies
Use a meter stick to mark off every 2.5cm on your strip of paper, and then draw a long line all the way down the center.
In every 2.5 cm box write four letters in any order, and in any combination that you want (A,T,G,C).
After you filled in the top, fill in the bottom with the complementary letter below.
Simulation of RFLP –pg 346
Make cuts at the A-T boundary Then measure each of the fragments with a
ruler; record the length on the back of each strip
Make the same chart as the in the TB and fill in the first column with your data.
Bring your data to me once you’re done.
Simulation of RFLP –pg 346
Length
1 2 3 4 5 6 7 8 9
13-20cm
1 5 3 3 2 3 1 3 5
9-13cm
2 2 2 4 5 2 3 4 4
6-9cm
0 0 4 4 7 4 6 3 1
4-6cm
3 0 5 4 2 2 4 2 2
2-4cm
2 4 5 3 2 3 8 4 2
0-2cm
1 1 5 2 2 1 8 9 0
Simulation of RFLP –pg 346
A DNA sample found at the scene of the crime with the following RFLP data came back from the lab…whose is it?
Simulation of RFLP
Length
?
13-20cm
4
9-13cm
4
6-9cm
2
4-6cm
3
2-4cm
6
0-2cm
10
PCR is a lab technique used to “copy and paste” a very small DNA sample
Need 50 percent less DNA than what is required for a RFLP test.
Polymerase Chain Reaction
Forensic scientists cut the DNA sample long ways, breaking the weak hydrogen bonds
Since the base pairs only bond in specific pairs, single bases are added and they automatically attach themselves in the cut DNA sample in the correct order.
This process is then repeated until there is enough DNA to complete a RFLP test
PCR
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
PCR Example
TACG
TGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
DNA sample found at crime, but too small to test
ACTGCTACGATGCATGCATGCATCAGATCAGTCGATGCATGCAGCTAGCTGATGCATGCTGACTGATGCTAGCTAGCTGATCGTAGCTAGCTGACTGATCGTAGCTAGCTGACGATCGTAGCTAGCTCGACTGATCGTAGCTGACTGATCGTAGCTAGCTGACGAGACGTAGCTAGCTGATGCAGCTGATCGATCGTAGCTCGACGAGCATCGAGCATG
TACG
TGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCTTAC
GTGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCTTAC
GTGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
After one split they have 2 times the original DNA
After two splits they have 4 times the original DNA
After three splits they have 8 times the original DNA
After ten splits they have 1024 times the original DNA
PCR
What is the point of PCR testing?
How is PCR different RFLP?
Checkpoint
Bellringer
Objectives
Movies Entomology Tests
Updates
New technique that is becoming more common than RFLP because it takes less time, less of a sample size, and is more exclusionary.
STRs are locations on the chromosome that repeats a specific sequence of two to ten base pairs.
Short Tandem Repeats
Thousands of STR sites have been identified
They are located on almost every chromosome in the body
Easily amplified using PCR
STR
Forensic scientists scan 13 DNA regions that vary from person to person
They use the data to create a DNA profile of that individual
There is an extremely small chance that another person has the same DNA profile for a particular set of regions
STR
STR analysis is now the primary method for genetic profiling
In 1992 the Innocence Project at the Cardozo School of Law started using STR tests to free wrongfully convicted people from jail. As of January 7th, 2014 312 have been exonerated As of May 29th , 2014 316 have been exonerated
STR
Why is STP more widely used today than RFLP?
Checkpoint
Mitochondria is the powerhouse of the cell, providing 90 percent of the energy a human needs to function
Each cell contains thousands of mitochondria, each containing several loops of DNA with 15,000-17,00 base pairs.
Unlike nuclear DNA, which if found on the chromosomes, mitochondrial DNA (mtDNA) is inherited only from the mother.
Mitochondrial DNA
Usually no change in mtDNA from mother to offspring
Individuals with the same maternal lineage are indistinguishable if mtDNA is used for analysis
You, your siblings, your Mom, your Mom’s siblings, your Grandma, your Grandma’s siblings, your Great Grandma, your Great Grandma siblings, and so on all share the same mtDNA!
MtDNA
Analysis techniques are more sensitive than other profiling techniques, more costly, and takes more time.
Cases in which hairs, bones, or teeth are the only evidence retrieved from a crime scene are particularly well-suited to mtDNA analysis.
MtDNA
When is MtDNA most commonly used?
How much does MtDNA change from mother to child?
When should you use RFLP, PCR, STR, and MtDNA analysis?
Checkpoint
A very small sample of DNA is found at the scene of a murder. You want to know whose it is. What DNA test(s) should you carry out to process the sample?
Example
Is it possible to fake your DNA results?
Dentist raped his patient when she was sedated. He installed a drain in his body with someone else’s blood. This way the DNA from his blood test wouldn’t match the DNA recovered from the woman.
Fake DNA
On pages 362 read the story in the blue box, then on page 363 read the case study.
1. How are these two stories similar?
2. How does DNA analysis help solve crimes by using old evidence?
3. Why is it important to build up data bases, and save evidence even after crimes have been cold for years?
Old Evidence
Use a meter stick to mark off every 2.5cm on your strip of paper, and then draw a long line all the way down the center.
In every 2.5 cm box write four letters in any order, and in any combination that you want (A,T,G,C).
After you filled in the top, fill in the bottom with the complementary letter below.
Simulation of RFLP –pg 346
What does RFLP stand for?
Bellringer
Finish our simulated RFLP DNA test.
Textbook questions
Notes on other DNA analysis
Objectives
Going left to right make a cut on the top strand at every AT sequence
Going right to left make a cut on the bottom strand at every AT sequence
Measure each of the fragments with your meter stick and write the length on the back.
Fill in the chart, and get data from at least 8 other pairs
Simulation of RFLP –pg 346
Length
1 2 3 4 5 6 7 8 9
13-20cm
4 3 2 2 4 4 0
9-13cm
4 2 3 1 2 3 2
6-9cm
2 2 1 4 2 2 2
4-6cm
3 0 3 8 5 3 14
2-4cm
6 1 3 7 4 3 10
0-2cm
10 4 1 10 1 3 10
Simulation of RFLP –pg 346
A DNA sample found at the scene of the crime with the following RFLP data came back from the lab…whose is it?
Simulation of RFLP
Length
?
13-20cm
9-13cm
6-9cm
4-6cm
2-4cm
0-2cm
Read pages 340 to 345 in the textbook and answer the following questions:
1. How and when was the first criminal case to use DNA evidence?
2. What type of blood cell contains DNA?3. How many nuclei are in a single drop of blood?4. Name 4 uses of DNA profiling5. What is used to release DNA from the
chromosome?6. What are the four main procedures involved in
DNA fingerprinting?
Forensic Uses of DNA
What is a RFLP DNA test?
Bellringer
Learn about other DNA analysis techniques besides RFLP
Bring laptops tomorrow if you don’t want to use the schools
Objectives
The DNA molecule is hundreds of thousands of base pairs long.
If you look at only a fragment of the DNA, what are the chances of someone else having the same size fragment?
1 in 5 million chance of someone else sharing your profile
Statistical Analysis in DNA Profiling
PCR is a lab technique used to “copy and paste” a very small DNA sample
Need 50 percent less DNA than what is required for a RFLP test.
Polymerase Chain Reaction
Forensic scientists cut the DNA sample long ways, breaking the weak hydrogen bonds
Since the base pairs only bond in specific pairs, single bases are added and they automatically attach themselves in the cut DNA sample in the correct order.
This process is then repeated until there is enough DNA to complete a RFLP test
PCR
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
PCR Example
TACG
TGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
DNA sample found at crime, but too small to test
ACTGCTACGATGCATGCATGCATCAGATCAGTCGATGCATGCAGCTAGCTGATGCATGCTGACTGATGCTAGCTAGCTGATCGTAGCTAGCTGACTGATCGTAGCTAGCTGACGATCGTAGCTAGCTCGACTGATCGTAGCTGACTGATCGTAGCTAGCTGACGAGACGTAGCTAGCTGATGCAGCTGATCGATCGTAGCTCGACGAGCATCGAGCATG
TACG
TGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCT
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCTTAC
GTGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
ATGC
ACGT
TATT
GCTA
ACTG
TCGA
CGAG
CAAT
CGCA
TGCTTAC
GTGCA
ATAA
CGAT
TGAC
AGCT
GCAC
GTTA
GCGT
ACGA
After one split they have 2 times the original DNA
After two splits they have 4 times the original DNA
After three splits they have 8 times the original DNA
After ten splits they have 1024 times the original DNA
PCR
What is the purpose if PCR DNA analysis?
Bellringer
Learn about STR, mtDNA, and fake DNA samples.
We’ll be working on the school laptops on Monday, so if you remember bring yours in if you can.
Objectives
Who would like to share their NEOTWY for this week?
Please pass up your NEOTWY’s
NEOTWY’s
New technique that is becoming more common than RFLP because it takes less time, less of a sample size, and is more exclusionary.
STRs are locations on the chromosome that repeats a specific sequence of two to ten base pairs.
Short Tandem Repeats
Thousands of STR sites have been identified
They are located on almost every chromosome in the body
Easily amplified using PCR
STR
Forensic scientists scan 13 DNA regions that vary from person to person
They use the data to create a DNA profile of that individual
There is an extremely small chance that another person has the same DNA profile for a particular set of regions
STR
STR analysis is now the primary method for genetic profiling
In 1992 the Innocence Project at the Cardozo School of Law started using STR tests to free wrongfully convicted people from jail. As of January 7th, 2014 312 have been
exonerated
STR
How can PCR tests help forensic scientists analyze DNA evidence?
What is the most common method of genetic profiling?
Checkpoint
Mitochondria is the powerhouse of the cell, providing 90 percent of the energy a human needs to function
Each cell contains thousands of mitochondria, each containing several loops of DNA with 15,000-17,00 base pairs.
Unlike nuclear DNA, which if found on the chromosomes, mitochondrial DNA (mtDNA) is inherited only from the mother.
Mitochondrial DNA
Usually no change in mtDNA from mother to offspring
Individuals with the same maternal lineage are indistinguishable if mtDNA is used for analysis
You, your siblings, your Mom, your Mom’s siblings, your Grandma, your Grandma’s siblings, your Great Grandma, your Great Grandma siblings, and so on all share the same mtDNA!
MtDNA
Analysis techniques are more sensitive than other profiling techniques, more costly, and takes more time.
Cases in which hairs, bones, or teeth are the only evidence retrieved from a crime scene are particularly well-suited to mtDNA analysis.
MtDNA
Is it possible to fake your DNA results?
Dentist raped his patient when she was sedated. He installed a drain in his body with someone else’s blood. This way the DNA from his blood test wouldn’t match the DNA recovered from the woman.
Fake DNA
The Phantom of Heilbronn
A string of killings between 1993 and 2009 all had the same DNA evidence, but were in Austria, France and Germany, and had no other connections.
The cotton swabs the detectives used to collect DNA samples already had DNA on them from someone in the factory that made the cotton swabs.
Fake DNA
On pages 362 read the story in the blue box, then on page 363 read the case study.
1. How are these two stories similar?
2. How does DNA analysis help solve crimes by using old evidence?
3. Why is it important to build up data bases, and save evidence even after crimes have been cold for years?
Old Evidence
What is the difference between RFLP, PCR, and STR testing?
Bellringer
Practice applying your knowledge of DNA and DNA analysis while learning about the history and issues of DNA evidence.
Objective
Grab a partner and a laptop
Go to my page on the Windsor School website http://www.windsor-csd.org/MrVERSPOOR.aspx
Click “Forensics” Download the PowerPoint labeled “Student
Copy – DNA Analysis” Follow the PowerPoint, and answer the
questions.
Laptop Activity
http://www.dnai.org/timeline/index.html
Go through the timeline and answer the following questions:
1. What did Friedrich Miescher do?2. Who discovered the double helix pattern of
DNA?3. What did Craig Venter do?
DNA Timeline
http://www.pbs.org/wgbh/nova/education/body/create-dna-fingerprint.html
Follow the link above and click view. Preform the RFLP test. Record the exact steps needed to fully
develop DNA fingerprints Who was guilty?
DNA Fingerprinting
http://www.innocenceproject.org/ Follow the link above, and answer the following
questions: What is “The Innocence Project” What is a false confession, how often do they occur,
and why do they occur? What is “Forensic Science Misconduct”, and what are
the two most common types of it? Why is eyewitness evidence not as reliable as DNA
evidence? How can bad lawyering lead to a false conviction?
The Innocence Project