DNA Profiling Flashcards
Describe the relationship between genes and chromosomes
Genes are segments of DNA on chromosomes that code for proteins/traits/characteristics
Describe the relationship between genes and alleles
Alleles are an alternative form of genes
Describe the relationship between introns and exons
Introns are junk DNA whereas exons are DNA segments that code for traits/proteins
Refer to the following description of the collection of DNA evidence at a crime
scene. Identify errors made during the collection of DNA evidence and provide
suggestions as to how those errors could have been avoided.
A break-in occurred at a jewelry store. The suspect was seen on security
cameras breaking a window and entering the shop. A piece of glass from the
broken window cut the suspect’s arm. A small piece of the suspect’s torn shirt
and some of his DNA were found at the crime scene. Two cigarette butts were
also found outside of the jewelry store near the broken window. Before the
crime-scene investigators arrived, the police officer used the empty zip-top bag
from his sandwich to collect the torn piece of the bloody shirt along with the two
cigarette butts, hoping to retain DNA evidence that could be used to identify the
suspect.
1) Officer placed all evidence in the same bag
- Every piece of evidence should go into a different container to avoid contamination
2) Officer did not secure the scene
- Officer should secure scene for investigators
3) Officer used a sandwich bag that was already contaminated and plastic
- Use sterile/clean and appropriate containers/paper for bloody clothes
What type of information can a DNA profile tell us? (list at least 4
pieces of information)
1) Maternity and paternity
2) Siblings/Other relations
3) Eliminate suspects
4) Match suspects to crime scene sample
5) Exonerate falsely imprisoned person
What type of evidence is DNA and explain why? You should have at
least 3 types of evidence DNA can be and why for each.
1) Circumstancial- DNA can place you at the crime scene
2) Biological- DNA comes from the body
3) Individual- DNA is unique so it can be linked to a single person
PCR or Polymerase Chain Reaction is a method for amplifying DNA.
What does that mean? and how does it occur?
1) Cut the DNA with restriction enzymes
2) Add polymerase and nucleotides
3) Heat the DNA to separate it and allow for replication
4) Run multiple cycles
Gel Electrophoresis can be used to help identify DNA matches. Use
the image to help explain how the Gel Electrophoresis works.
1) Place DNA samples in wells on the negative side
2) Turn on power- because DNA is negative the fragments will be pulled to the positive side
3) The DNA fragments will move based on size- the smallest going the fastest and furthest on the gel
4) The end result is a DNA profile
Should DNA evidence alone be sufficient to convict when there is
no corroborating evidence? State your opinion and provide support
for it.
No- DNA can place someone at a crime scene, but it does not specifically show that they were responsible for the crime especially if there is no corroborating evidence. They could have left behind DNA at the crime scene prior to when the actual crime happened.
The primary function of DNA is to
a.
make proteins.
b.
store and transmit genetic information.
c.
control chemical processes within cells.
d.
prevent mutations.
B
ATTG : TAAC ::
a.
AAAT : TTTG
c.
GTCC : CAGG
b.
TCGG : AGAT
d.
CGAA : TGCG
C
DNA restriction (special) enzymes
a.
are used to produce more DNA fragments
c.
cut DNA into restriction fragments for gel
electrophoresis
b.
determinne sex in a karyotype
d.
are the same in all humans
C
Which is true regarding DNA collection?
a. DNA is only collected from suspects in murder and rapes.
b. DNA evidence is destroyed after five years to reduce storage problems faced
by law-enforcement organizations
c. DNA must be collected in a plastic bag to prevent contamination
d. DNA evidence found in trace amounts can be used to solve crimes
D
In the strawberry lab, why did we mash the strawberries up in a bag?
To destroy the cell wall
Why did we add soap to the strawberry mix?
To get through the nuclear membrane. The membrane is non-polar and so is soap so it dissolves the membrane.
