Exam 1 Flashcards
latin meaning of forensic
“of the forum”
lochards exchange principle
every contact leaves a trace
who do forensic scientists work for?
law enforcement or as civilians
how many labs are in the us?
400
what are bode labs used for?
paternity testing
what is a crime scene?
where the forensic world is established
goal of processing crime scene
collect and preserve evidence for later analysis
primary location vs secondary location
primary- original crime scene
secondary- subsequent crime scene
macro vs micro scopic location
macro- one location
micro- specific types of physical evidence
steps to process crime scene
plan of action, secure scene, survey, document, search, and collect
1st on the scene duties
detain suspects, provide medical assistance if needed
crime scene documentation
measurements, notes, photos, and sketch
measurements
must be taken from 2 pem points
photos
taken with and without scale
patterns of searching
spiral, zone, line, and grid
liquid evidence vs biological evidence
airtight container v nonairtight
what must happen to the containers after packaging?
sealed with signature on seal
trier of fact
whoever determines guilt or innocence
chain of custody
ppl who come in contact with evidence
real vs augmented evidence
real- blood and fingerprints
augmented- created like diagrams and drawings
direct v indirect transfer
direct- source to location with no intermediaries
indirect- one or more intermediaries
persistence
duartion which evidence remains in location before further transferred
contamination
undesired transfer between items of evidence
individualization
one unique characteristic exists in known and unknown samples
class
group of objects share similar characteristics
mode of production
concept of common source depends on material in question
coincidental association
helps to determine what evidence is significant and what may be ignored
2 fundamental processes of analysis of evidence
identification and comparison
identification
process of discovering characteristics of evidence with eye putting it into similar classes
comparison
done to establish sources of evidence
control
source is known and used for comparison with unknown evidence
positive v negative control
positive- positive result, shows test is working
negative control- negative result
false positive
type 1 error, falsely accused, no negative control used
false negative
type 2 error, falsely exonerated, no positive control used
gene
consists of base pairs and is the fundamental unit of heredity
dna
composed of nucleotides
nucleotides
composed of series of linked repeating units
backbone v base composition
backbone- sugar
base- nitrogen structure
base pairs
adenine- thymine
guanine- cytosine
who created the stucture of dna?
watson and crick; rosalind franklin
cellular dna
arranged in chromosomes, 22 matched pairs of autosomes responsible for genetic makeup
how many chromosomes do we have?
23
mitochondrial dna
only maternal dna, more viable than nueclar
polymorphic genes
exists in more than 1 form
alleles
polymorphic forms of dna
sequence polymorphism
difference in one or more base pairs without gene
length polymorphism
repeating sequence of base pairs called tandem repeats
what systems were used before dna typing?
ABO and Rh system
why is RFLP not used anymore?
expensive and time consuming
short tandem repeats
repeated sequences of bases, acts as a filler, and most successful DNA profiling, includes 2-7 base pairs
polymerase chain reaction
technique for amplifying small quantities of dna
done ex situ
outside of living cell
process of polymerase chain reactions
- dna is heared and seperated
- primers added to link to single strand
- nucleotides added to rebuild
- process repeated 2-3 times
extraction
break open cells to seperate dna from rest of cells
amplification
make millions of copies of dna
quantification
how much dna is present and the quality of the dna
polymerase chain reaction
created by dr kary mullis, makes copies of DNA in machine called thermocycler
gel electrophoresis
seperate various STRs by use of electricity, separates DNA based on size
potential sources of dna
toothbrush, blood, gum, and hat
bruccal sample
from inside cheek
what happens after samples are collected?
dna profile is created
CODIS
combined dna index system
PCR
cold cases with partial dna revisted
innocence project
created by barry sheck and peter neufeld.
provides assistance to ppl convicted of crime prior to DNA typing
