Download DNA - Belle Vernon Area School District

DNA Drill
What does DNA stand for and state its
importance?
Who discovered DNA & when?
Who is the father of genetics? State his
three laws.
Drill
• Name some sources of biological
evidence.
• Explain junk DNA.
• How are VNTR’s differ from STR’s?
DNA Fingerprinting
DNA Analysis & Typing
DNA Analysis
All living things have genetic
material that is
.
Found in the
eukaryotic organisms.
of
What is DNA
1. Deoxyribose
Nucleic Acid
2. Double
.
3. Nucleotide building blocks
a.
back bone
b.
sugar
c. nitrogen containing base
(
different bases)
,
,
.
Who Discovered DNA
1.
1.
&
.
(Rosalind Franklin)
.
Function of DNA
1.
1.
genetic information to
the cells activity.
on genetic information
from one generation to the next.
Who Discovered Genetic
Inheritance?
1.
.
2. Austrian monk
3. Degrees in math and
biology
4. Gardner
5. Notice patterns in
pea plants
6. Developed
laws
of genetics
Mendel 3 laws of Genetics
1. Law of
.
Dominant trait masks the weaker trait.
2. Law of
Traits go into gametes independently from
one another.
3. Law of
Traits separate into gametes
Introduction and History of
Biological Evidence in Forensics
•
DNA
, also known as DNA
is used in criminal or legal cases with a high
degree of accuracy.
•
Biological evidence such as
, saliva,
urine, semen, and
are examined for
the presence of inherited traits.
•
What examples can you give of how laboratory
techniques used in forensics were originally
developed for other purposes?
,
DNA Identification
•
contains many of the unique patterns of
repeated base sequences that identify individuals.
• In a human population, these are called
•
• In
a technique was developed for
.
isolating and analyzing these variable areas.
• This DNA Fingerprinting appears as a
on
X-ray film. These patterns can be used for identification
of individuals.
DNA Identification
The number of copies of the same repeated base
sequence in DNA varies among individuals.
•
•
•
•
(VNTR)
Within junk DNA, sequences of DNA are
repeated multiple times.
Some can be
bases in length.
(STR)
Within junk DNA, other sequences of DNA also
are repeated multiple times.
These usually are only
bases in
length and are becoming the preferred
sequences for analysis.
DNA Profiling and DNA
Population Databases
•
VNTR and STR data are analyzed for (a) tissue
matching and (b) inheritance matching.
•
is the study of
variation in genes among groups of individuals.
•
Calculations can be made based on these
groups to determine the
a
random person would have the same
alternative form of a gene (an allele) as (a) a
suspect in a crime or (b) an alleged father in a
paternity case.
Avoiding contamination in
the collection and
preservation of DNA
1. Use
2.
3.
4.
5.
gloves and
collection instruments.
Avoid
, talking, sneezing,
and coughing in the evidence area.
evidence and put it into
new paper bags or envelopes.
If evidence cannot be dried,
.
Keep evidence
during
transportation and storage.
Preparing DNA Samples
for Fingerprinting--Extraction
1. Cells are
from biological
evidence such as blood, saliva, urine,
semen, and hair.
2. The cells then are
to
release the
from proteins and other
cell components.
3. Once released, the DNA can be
from
the cell
.
Preparing DNA Samples
for Fingerprinting
.
• With some VNTR analysis, polymerase chain
reaction (PCR) can be used to
the
DNA that contains the VNTRs.
• In STR profiles,
are
unnecessary; PCR allows the amplification of
the strands with STR sequences.
.
• DNA samples are placed in
through
which electronic currents are passed.
• DNA fragments line up in
along the
length of each gel
Probes
• DNA
are used to identify the
unique
in a person’s DNA.
• Different DNA probes are made up of
different synthetic sequences of DNA
bases
to the DNA strand.
• The probe
to complimentary
bases in the strand (see the fragmentary
DNA bands above).
• In most criminal cases,
probes
are used.
Analysis of
DNA Fingerprints
and Applications
•
and
samples of DNA.
are
in matching
• DNA fingerprinting can:
(a) match
DNA with a
,
(b) determine
,
, or
match to another relative,
(c)
a suspect,
(d) free a
imprisoned individual, and
(e)
human remains.
Human DNA
1. Contain on
2.
.
species has their
own chromosome
.
3. Humans have
.
chromosomes.
Genetic markers
Molecules, usually
proteins that are
attributable to a specific
gene; any person can
have two of several
different genes at this
location on DNA, and
that is reflected in the “
.
” profile.
Collection & Preservation of
Biological Evidence for DNA typing
Same as before:
Thoroughly
packaging.
before
bags.
Polymerase Chain Reaction
a specific
segment of DNA into
.
of copies.
Useful in taking a small
sample of DNA and
amplifying it.
Restriction Fragment Length
Polymorphism (RFLP)
Involves
DNA
into smaller pieces
with specific
enzymes.
Then separating these
pieces by
.
Narborough Rape Murders
First case to use DNA typing – 1983.
15 year old girl was raped and murdered.
No evidence.
Three years latter another girl in Narborough was
raped and murdered in a similar manner.
17 year old Rodney Buckland was arrested making
a statement in the second murder but
proclaiming his innocence in the earlier one..
Semen samples from both attacks and blood from
the suspect.
DNA analysis confirmed the same offender had
committed both crimes but it also showed
Buckland could not have been the perpetrator.
First man to be exonerated by
DNA typing.
All males (over 5,000) had DNA
collected from them in the
town.
Professor Jeffery's agreed to do
the testing because there was
not DNA typing lab.
DNA was screened with genetic
markers by using RFLP’s.
Remaining were DNA typed.
In first round none of the DNA
matched.
27 year old Colin Pitchfork was
ultimately found and arrested
because he paid someone to
give the blood voluntary by
using his name.
He was bragging about it while
drinking at a pub.
Electrophoresis
Tommy Lee Andrews – The first
DNA Criminal Case in the USA
1986 a women in Florida was assaulted in
her home by a stranger.
Fingerprints outside her home lead to the
arrest of Tommy Lee Andrews.
At trial the jury was unable to reach a verdict
and was declared a mistrial.
While preparing their retrial they heard about DNA typing –
new form of biological evidence.
Semen evidence and DNA from Andrews was sent to
Lifecode Corporation in New York for testing.
RFLP pattern from evidence matched that of Andrews.
The second trial admitted the DNA evidence and the jury
heard from Lifecode scientist that the odds of the DNA
being from someone else were 1 out of 10 billion.
The Florida court upheld the court’s decision in admitting
the DNA and the conviction stood.
. . . . . . . . . . Summary . . . . . . . .
• DNA contains the information needed for replication
in a sequence of nitrogenous bases.
• DNA analysis allows even a small sample of tissue
to be identified with a single individual.
• DNA contains, in non-coding regions called junk
DNA, many repeated sequences that vary in number
between individuals.
• These differences between individuals can be used
to produce a DNA fingerprint for an individual.
. . . . . . . . . . . . . . . . . Summary
• Polymerase chain reaction (PCR) for DNA
amplification has largely eliminated the
problem resulting from the tiny samples
usually available.
• DNA evidence must be collected carefully
to avoid contamination with other DNA.
• DNA analysis involves extraction,
electrophoresis, and visualization.
• DNA profiles are kept by police agencies
in electronic databases.