Transcript Enzymes Forensics

Enzymes Forensics
Allison, Ronnie, Shyann and Weena
What is Forensics?
• Scientific techniques or tests used to
investigate crime scenes with the aid of
saliva, blood, urine, hair, sweat and other
bodily substances
What are Enzymes?
Substance produced by living organisms which
acts as a catalyst to bring about a specific
biochemical reaction.
Enzymes in Forensics
This is when crime scene investigators inspect
crime scenes using enzymes. For example,
blood, spit, sweat and many more human
secretions can be tested to assess how the
victim was killed and with what methods.
-------------Enzymes are biomolecules that catalyze important
biochemical reactions. Understanding the function of
enzymes has allowed scientists to harness their
properties to drive specific laboratory processes.
Restriction Enzymes
● Scissors like enzymes that “cut” DNA at
specific known DNA sequences
● The separated pieces have single stranded
“sticky pads” which allow the
complementary pieces to combine
● There are 3 main types
○
type I, type 2, type 3
Three main types of
Restriction Enzymes
TYpe II Enzyme
Type III Enzymes
Type I Enzymes
Protein structure
separate endonuclease
and methylase
bifunctional enzyme of
2 subunits
bifunctional enzyme of
3 subunits
Recognition site
short sequence (4-6
bp), often palindrome
asymmetrical sequence
of 5-7 bp
bipartite asymmetrical
CLeavage site
same as or close to
recognition site
24-26 bp downstream
of recognition site
nonspecific > 1000 bp
from recognition site
Restriction &
methylation
separate reactions
simultaneous
mutually exclusive
ATP need for
restriction?
no
yes
yes
Blood Typing
● Blood is the most common and well known
evidence
● Dried blood cells split open causing clumping
patterns,this makes it hard to identify blood
types
● Blood enzymes are proteins that accelerate
biochemical processes related to the heart or
blood. ex. Cardiac Enzymes
● These enzymes do not change making it
possible to identify individuals unique genetic
markers allowing us to determine the
individual’s role in the crime
Saliva Samples
● Saliva is composed of water, enzymes, mucus, and
epithelial cells from the inside of the cheeks, which
makes it ideal for DNA profiling
● A saliva sample has become the most common form
when carrying out DNA-testing.
● Saliva tests can reveal certain viral infections, and
the presence of therapeutic as well as illicit drugs.
● Saliva is rich in amylase an enzyme that breaks
down complex carbohydrates into smaller sugar
molecules
● Useful for forensics because through catalyse, it can
be decided on whose saliva it is i.e victim or killer
Bone, Teeth, Hair and Urine
● Bone makes up the skeleton, using minerals calcium
carbonate) and collagen. The structure makes it
resistant to decay, physical attributes like size, shape,
and injury location are what makes bone so essential for
DNA typing.
● Similar to bone, but it is used through dental records to
identify a person who has been burned alive.
● Hair is made out of a protein called keratin, which is
very useful because it has three stages, when the hair is
at the catagen phase, the enzyme catalase can be used to
identify the person through nuclear and mitochondrial
DNA testing.
● Urine has an acid called urea, made through the
metabolic process of the body through enzymes. With
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http://www.youtube.com/watch?v=drC7rR7CI
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