Chapter 12 DNA Analysis. Identify individuals from unique genetic code In every nucleated cell in the human body Can be extracted from blood, semen, urine, bone, hair follicles, and saliva. In the nucleus of each cell are 46 chromosomes.
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Chapter 12 DNA Analysis
In the nucleus of each cell are 46 chromosomes.
Each chromosome is made of long strands of DNA wrapped around proteins called histones.
You have 23 pairs of chromosomes
One copy is from each parent.
A gene is A segment of dna that contains the instruction s to make a protein
There are about 20,000-25,000 genes in the human genome. Most of your DNA (98%) does not code for proteins.
Deoxyribonucleic Acid is a macromolecule containing the sugar deoxyribose.
It is a polymer made of two strands of repeating units called nucleotides.
Each nucleotide is made of three parts…a sugar, a phosphate group, and a nitrogenous base.
There are only four different nitrogenous bases…Adenine
Gene; a segment of DNA that codes for a particular protein
One strand of nucleotides
The hydrogen bonds are very weak, so the two strands can “unzip” allowing the base sequence to be “read” when the DNA copies itself, or when the gene’s instructions are used to create proteins.
Every three bases codes for one amino acid. A long string of amino acids make up a protein, and our proteins that we make give us our traits.
Jack the Ripper
The order of the 3 billion base pairs is 99.9% identical in all humans. The unique 0.1% gives us incredible diversity.
found in the nucleus
constitutes 23 pairs of chromosomes inherited from both parents
each cell contains only one nuclei
found in the cytoplasm
is inherited only from mother
each cell contains hundreds to thousands of mitochondria
can be found in skeletal remains
Nuclear DNA is present in the head of the sperm. Mitochondrial DNA is present in the tail. At conception, the head of the sperm enters the egg and unites with the nucleus. The tail falls off, losing the father’s mitochondrial DNA.
Typically blood and other bodily fluids provide DNA for forensic testing and determining a DNA profile, or fingerprint.
Uses of DNA Fingerprinting:
Identify potential suspects
Clear the wrongly accused
Identify Crime and Catastrophe victims
Match organ donors and recipients
1. After isolating the DNA from the cell, restriction enzymes are used to “chop up” the DNA into small pieces (or DNA “fragments”). Different restriction enzymes recognize different DNA sequences and therefore cut the DNA at different places in the sequence. You end up with many fragments of different lengths (they’re polymorphic).
2. Now, the many fragments are separated by gel electrophoresis. A gel provides a barrier through which the DNA fragments can slowly travel. An electrical current draws the negatively charged DNA from one end of the gel to the other, but the polymorphic fragments don’t travel at the same speed, so they’re separated by size and charge.
Unique banding pattern is your DNA profile or DNA fingerprint
STR’s are locations (loci) on the chromosome that contain short sequences
of 2 to 5 bases that repeat themselves in the DNA molecule. They are “markers” not found in the “coding” part of a gene.
One commonly used STR
5 – 11 repeats of A-A-T-G on chromosome 11 in the introns of the tyrosine hydroxylase gene
There are 7 variants of THO1 in humans
Short Tandem Repeats (STR)
FBI’s CODIS DNA Database
Is a measure
of the likelihood
that 2 random
will have an identical
By multiplying their frequencies
Having the first 3 STRs match is
1 in 5000
D3S1358 0.097 0.080
vWA 0.074 0.068
FGA 0.036 0.041
8/100 x 6.8/100 x 4.1/100 = 223 / 1 000 000
≈ 1 / 5000in the U.S. Caucasian population
For the first 6 STRs
1 in 2 million
all 13 STRsis
1 in trillions
(1 trillion= 1 000 000 000 000)
Three Possible Outcomes
The website below has a STR animation demonstration. Click on human identification, profiling and then on the third circle called Today’s DNA Profiling to see the demonstration.
Nicole Brown Simpson’s blood a match for the blood on a piece of evidence.
A. Identification of remains
The Angel of Death:
was a Nazi
war criminal notorious for grotesque human experiments that he carried out at the Auschwitz concentration camp.
After the Second World War he fled from the Allies and escaped to South America.
The fugitive succeeded in living out the rest of his days without being caught.
Using DNA extracted from blood provided by Mengele’s ex-wife and son, it was concluded that it was more than 99.94% certain that the skeleton was Mengele’s
B. Paternity Cases
Who’s your daddy?
Third president of the United States (1801–1809)
Principal author of the Declaration of Independence and one of the most influential Founding Fathers for his promotion of the ideals of republicanism in the United States
President John F. Kennedy welcomed
forty-nine Nobel Prize
winners to the
White House in 1962
"I think this is the most extraordinary collection
of talent and of human knowledge that has ever been gathered together
at the White House– with the possible exception
of when Thomas Jefferson dined alone.”
Jefferson has been consistently ranked
by scholars as one of the
many slaves over
Some find it baffling
that Thomas Jefferson
yet was outspoken
that slavery was immoral
it should be
Biographers point out that
Jefferson was deeply in debt
and had encumbered
his slaves by notes
he chose not to free them until he finally was debt-free,
which he never was.
Sally Hemings (1773)
In a Richmond
one of his own slaves”
Madison and Eston claimed that
Jefferson was their father.
This belief was passed down through the generations.
Denied by his children on practical and moral grounds
Jefferson descendants claim that Jefferson’s nephews – Peter and Samuel Carr – were the fathers of the light-skinned Monticello slaves some thought to be Jefferson’s children.
was sustained throughout the 19th century by:
British critics of US democracy
Tested Y- chromosomal DNA samples from male-line descendants of
(3) Found that an individual
of Sally Hemings.
No, it means that he COULD BE the father of EstonHemings.
who carried this chromosome living in Virginia at the time, and a few of them are known to have visited Monticello
“Jefferson Fathered Slave’s Last Child”
issued a report in January 2000 concluding that there is a strong likelihood that Thomas Jefferson was the father of at least one and perhaps all the children of Sally Hemings.
The Monticello Association
An organization for descendants
of Thomas Jefferson
refused to recognize and admit
any descendants of Sally Hemings
was a slave at Monticello,
Lady’s maid to daughters Martha and Maria
Nursemaid - companion
to Jefferson’s daughter
No known images of Sally Hemings
It is not known
if she was
Some of Sally’s children
Strongly resembled Jefferson
Freed by Jefferson during his lifetime:
Freed in 1826-1827, by the terms of Jefferson's will:
Left Monticello, with Jefferson's tacit consent, in 1804 and 1822:
JEFFERSON GAVE FREEDOM
NO OTHER NUCLEAR
A family history of being related to Thomas Jefferson
Who have lived as African-Americans
a family history
Thomas Jefferson and
Stands by its original findings - that the weight of evidence suggests that Jefferson probably was the father of Eston Hemings and perhaps the father of all of Sally Heming’s children – but is ready to review new evidence at any time and to reassess its understanding of this matter in the light of new information.