DNA Profiling in Forensic Investigations by

Bibliography

hstevens8 — 2017-09-02 18:42:04 UTC

Freeman, Shanna. “How DNA Profiling Works.” HowStuffWorks Science, HowStuffWorks, 19 Aug. 2008,

Norrgard, Karen. “Forensics, DNA Fingerprinting, and CODIS.” Nature News, Nature Publishing Group, 2008

Walpole, Brenda, et al. 3.5. Biology for the IB Diploma, 2nd ed., Cambridge University Press, 2011.

Benefits

hstevens8 — 2017-09-02 18:42:25 UTC

-near guaranteed match if properly acquired (no two fingerprints/people are genetically the same)
-can provide irrefutable evidence in otherwise unsolvable cases
-holds more weight than any circumstantial evidence, easier for prosecutors to convict a suspect as a result

Risks

hstevens8 — 2017-09-02 18:42:30 UTC

-difficulty acquiring samples (small quantity, not preserved,
-alleles can be similar/identical, though very rare
-can be seen as unethical in general, widespread collection of data and disregard for privacy cause for concern

Introduction

hstevens8 — 2017-09-02 18:45:25 UTC

At a crime scene, forensic scientists check for fingerprints because a person's fingerprint is unique and can be used to identify them. Forensic scientists also collect samples of hair, skin, blood and other body fluids left at a crime scene because they all contain a person's DNA and that too is a unique record of their presence. This DNA evidence is then used in the court of law to accurately connect a suspect to the crime scene.

DNA Profiling - What is it?

hstevens8 — 2017-09-02 18:47:34 UTC

Matching the DNA from a sample to a known individual is called DNA profiling. In forensic science, DNA profiles from crime scenes can be used for...
-establishing the possibility of guilt/prove a suspect innocent (criminal)
-determining paternity (civil)
-eugenics (improvement of traits via genetic manipulation)

hstevens8 — 2017-09-02 18:51:21 UTC

How does it work?

hstevens8 — 2017-09-14 00:58:46 UTC

Although the majority of genetic material (genome) in humans is identical across all individuals, there are regions of variation. This variation can occur anywhere in the genome, including areas that are not known to code for proteins. Within the non-coding regions of an individual’s genome there exists satellite DNA – long stretches of DNA made up of repeating elements called short tandem repeats (STRs). Investigation into these nucleotide pairs noncoding regions reveals repeated units of DNA alleles that vary in length among individuals, allowing for analysis and comparison between these unique individuals after extraction via gel electrophoresis. As for the actual extraction process, there are many methods that have been changed and improved upon since DNA profiling's inception in 1987, with one method being outlined below.

Ethics

hstevens8 — 2017-09-14 01:09:36 UTC

Under what circumstances should an individual be compelled to provide a DNA sample? Withholding your fingerprints as a suspect can be considered obstruction of justice and thus is a crime itself, but is it truly ethical to store a massive database of DNA that can link you to a crime scene, even if you have committed a crime in the past? Additionally, the small margin of error can have severe implications on a wrongly identified suspect, possibly costing them jail time if prosecution is not carried out correctly.

hstevens8 — 2017-09-14 13:36:10 UTC

Questions

hstevens8 — 2017-09-14 15:10:18 UTC

1. List 3 different ways DNA profiling can be used. (3)

2. Outline the process of DNA profiling. (4)

3. Analyse the ethics of law enforcement having banks of DNA samples. (4)

Total Marks: 11

hstevens8 — 2017-09-14 21:19:30 UTC

hstevens8 — 2017-09-14 21:33:46 UTC

Step 1

hstevens8 — 2017-09-15 15:00:49 UTC

A DNA sample is collected (from blood, semen, saliva, skin sample, fingerprint etc.) and then amplified using polymerase chain reactions (PCR).

Step 2

hstevens8 — 2017-09-15 15:01:25 UTC

Satellite DNA and STR sequences) are cut with specific restriction enzymes to generate fragments.

Step 3

hstevens8 — 2017-09-15 15:01:30 UTC

Fragment length will differ amongst individuals due to the variation in length between their short tandem repeats (STRs).

Step 4

hstevens8 — 2017-09-15 15:01:34 UTC

The fragments are then separated using gel electrophoresis and the resulting profiles are compared (shown in adjacent image).

How DNA Profiling Works (in general)

hstevens8 — 2017-09-15 15:05:03 UTC

Answers - Alex

hstevens8 — 2017-09-18 02:07:39 UTC

1. -establishing the possibility of guilt/prove a suspect innocent (criminal)

-determining paternity (civil)

-eugenics (improvement of traits via genetic manipulation)

A DNA sample is collected (from blood, semen, saliva, skin sample, fingerprint etc.) and then amplified using polymerase chain reactions (PCR).
Satellite DNA and STR sequences) are cut with specific restriction enzymes to generate fragments.
Fragment length will differ amongst individuals due to the variation in length between their short tandem repeats (STRs).
The fragments are then separated using gel electrophoresis and the resulting profiles are compared (shown in adjacent image).

overall,the small margin of error can have severe implications on a wrongly identified suspect, possibly costing them jail time if prosecution is not carried out correctly.

Answers - Milan

hstevens8 — 2017-09-18 02:07:44 UTC

Establishing the possibility of guilt, determining paternity, eugenics
Step 1 DNA is collected, Step 2 Satellite DNA and STR are cut with specific enzymes restriction . Step 3 Fragment length will differ amongst individuals. Step 4 The fragments are often separated using gel electrophoresis.
Difficult acquiring samples, alleles can similar, evidence easier from prosecutors to convict suspect for the result and can provide irrefutable evidence.

Answers - Spencer

hstevens8 — 2017-09-18 02:07:49 UTC

1. DNA profiling can be used for establishing the possibility of guilt or proving a suspect is innocent (criminal usage), determining the paternity of a child (civil usage), and eugenics, which is the improvement of traits via genetic manipulation (luxury usage).

2. A DNA sample is collected from a range of sources, such as blood, semen, saliva, fingerprint, etc. and then amplified using polymerase chain reactions (PCR). Then, satellite DNA and STR sequences are cut with specific restriction enzymes to generate fragments. Their fragment length will differ amongst individuals due to the variation in length according to to their short tandem repeats (STR's). The fragments are then separated using gel electrophoresis and compared.

3. It may seem to some that it is unethical to take a DNA sample, as it is considered intrusive to some. However, not doing so can be seen as obstruction of justice which is a crime in itself. Having the massive database of DNA makes crime investigation easier, and having a smaller amount can result in a larger margin of error which can consequently cause the incorrect person being framed for a crime they did not commit.