Unit 5: DNA Profiling Flashcards
DNA profiling
a technique used to identify a person based on analysis of their genetic code
DNA profile
pattern of DNA fragments (fingerprint) obtained by analyzing a person’s unique sequence of noncoding DNA
DNA is _____ evidence
individual
forensic genealogy
using both CODIS and OSACs databases to identify a subject by comparing their DNA to one or more family members
Alec Jefferys
conducted the first forensics personal identification of a murder suspect, Colin Pitchfork, using DNA fingerprints
Polymorphisms
regions of repeating DNA within an individual that is highly variable from person to person. These occur in less than 1 percent of our DNA
1994
the DNA identification act allocated funds to improve labs and communication between departments
1998
the FBI launched CODIS
what is CODIS?
(Combined DNA Index System) a database of convicted offenders and arrestees. keeps record of all missing persons and unidentified remains
rapid DNA kits can produce a ___ profile in ___ minutes
DNA; 90
DNA
deoxyribose nucleic acid; the genetic material of all living things
all humans contain DNA in the cells ___ and ___
nucleus; mitochondria
most DNA is ___(junk) DNA
noncoded
human genome
all of the DNA found in a cell
DNA is a ___
polymer
polymer
a long repeating molecule composed of repeating units call nucleotides
nucleotides
the basic unit of DNA consisting of a sugar, a phosphate, and a nitrogen base
the four nitrogen bases are:
adenine, guanine, cytosine, and thymine
1953
Watson, Crick, and Wilkins won a Nobel peace prize for describing DNA as a double helix shape
phosphate and sugar make up the __ of the ladder; nitrogen bases make up the ___ of the ladder
handles/side; steps
sex chromosomes
are the x and y chromosomes; these contain genes to determine the sex of a person
there are __ chromosomes within the human body; __ are the sex chromosomes; the rest __ are called autosomes
46; 2; 44
karyotype
an organized picture of a person’s chromosomes
genes
the basic physical, functional unit of heredity; composed of DNA and located at specific locations on each chromosome
alleles
an alternative form of a gene and are the 0.1 percent of our DNA that makes us unique
introns
noncoding DNA and make up 95% of our genes; these are the “on and off” switch for protein production
exons
coding sequence that expresses a protein
electrophoresis
a method of separating molecules, such as DNA, according to size
gel electrophoresis steps:
- collect DNA
- extract and isolate from cells
- add restriction enzymes
- load crime scene and suspect DNA into separate wells
- apply an electric field towards the positive end of the gel
- shorter DNA fragments move faster than longer DNA fragments
restriction enzymes
they cut DNA at specific sites found within the sequence to create DNA fragments
shorter DNA mover ___; longer DNA move ___
faster; slower
true or false: STR analysis has been replaced by gel electrophoresis
false; it’s the other way around
1991
STR was created and founded
STR (short tandem repeats)
sequence of repeating bases in the variable regions of DNA that are used in DNA profiling
STRs are ___ than DNA sequences and consist of fewer than __ bases
shorter; 50
STR sequences are found at specific _____ on chromosomes referred to as ___ which are located in ___
`location; markers; introns
the FBI originally used __ core STR markers; we now use __ STR markers
13; 20
homozygous genotype
two of the same marker
heterozygous genotype
two different markers
allele frequency
calculation of how often a particular allele appears within a given population
steps of STR analysis:
- DNA is extracted and isolated from cells
- fluorescent primers are added to amplify DNA
- amplified STRs are sorted by size as they pass through gel electrophoresis
- primers pass through a light source that allows them to absorb and emit light
- prism separates light in wavelengths
- signal is recorded as a colored peak
- organizes data to produce an STR profile
primers
-short sequences that stimulate the replications of specific locations on DNA
- STR amplification is completed through the Polymerase Chain Reaction (PCR)
the sex chromosomes have an ____ marker which determines whether a person is male or female
AMEL; the AMEL marker regulates tooth enamel