WHAT IS DNA AND HOW CAN WE USE IT AS EVIDENCE? MAY 30, 2014.

W H AT I S DNA AND H O W C A N W E US E I T A S E V I DE NC E ? M AY 30 , 2014

F I N D T H E D I F F E R E N C E S B E T W E E N T H E P H O T O S B E LO W

AG E N DA

• What is DNA?

• How is DNA Replicated?

• What type of evidence is DNA?

• How can we test DNA?

• Paternity Testing

R E M I N D E R S

• If you have not taken your test, you must take it today

• If you know you are failing the course, see me after class

• Check powerschool to see your grades

D N A • Deoxyribonucleic Acid

D N A• Major function is to provide

instructions for the cell to make proteins and copies of itself

• Like a cookbook, with instructions to make each part of the cell and everything it needs to work

• DNA is heritable (it gets passed on)

D N A A S E V I D E N C E

• Circumstantial and Individual

• Found in:

• Saliva

• Semen

• Blood

• Skin

• Urine

• Hair

D N A A S E V I D E N C E

• DNA can be used to link a suspect to a crime, identify a suspect, and identify remains.

• DNA fingerprinting is the technique used to identify people

• Most samples found at the scene of the crime are small, and must be amplified to be tested

G R E E N R I V E R K I L L E R

• Gary Ridgway

H TT P : / /W W W. B IO G RA P H Y. CO M /P E O P L E /G A RY- R ID G WAY- 1 0 07 3 4 0 9 / V ID E O S /G A RY- R ID G WAY- M IN I -B IO G RA P H Y- 2 1 6 5 7 6 47 0 4

D N A S T R U C T U R E

• Watson and Crick are credited with discovering the structure of DNA

D N A S T R U C T U R E

• DNA looks like a ladder, but is in the shape of a double helix

• This allows for improved storage and protection. Without this, mutations would occur frequently.

D N A S T R U C T U R E

• DNA’s backbone is made up of sugars and phosphates

• The rungs of the ladder are made up of bases that are in pairs

D N A S T R U C T U R E

• DNA has four bases that pair together in specific ways:

• Adenine (A)

• Thymine (T)

• Guanine (G)

• Cytosine (C)

• A with T and C with G

D N A S T R U C T U R E

• DNA Replicates by unzipping itself and making new copies (semiconservative replication)

D N A F I N G E R PR I N T I N G

• Individuals have unique sequences of repeated DNA patterns in the non-coding region of DNA (doesn’t become protein)

• Variations called polymorphisms

• Polymorphisms give each person a unique DNA fingerprint

• Different sequences are seen in the genome of an individual (entire genetic code)

• Two type of repeats used are VNTR and STR

D N A F I N G E R PR I N T I N G

• VNTR

• Variable Number of Tandem Repeats

• 9 to 80 bases long

D N A F I N G E R PR I N T I N G

• STR

• Short Tandem Repeats

• 2 to 5 bases long

• Easier to use

S T E P S I N D N A F I N G E R P R I N T I N G

1. Extraction

2. PCR

3. Gel Electrophoresis