DNA ProfilingC_Daniel Yoon

What is DNA Profiling?A technique used to identify individual by encrypting sets of numbers that reflect a person’s DNA makeup. (Often used in parental testing and criminal investigation)

Assessment Statement related to DNA Profiling

4.4.3 State that gel electrophoresis of DNA is used in DNA profiling.

4.4.4 Describe the application of DNA profiling to determine paternity and also in forensic investigations.

4.4.5 Analyse DNA profiles to draw conclusions about paternity or forensic investigations.

How does gel electrophoresis work?

Gel electrophoresis is used to separate DNA (or other molecules) by their size and charge. The DNA fragments move in an electric field. The negatively charged DNA all moves towards the positive electrode. Small pieces move farther than large pieces.

Procedure of DNA Profiling

1. DNA samples are taken and amplified with PCR

2. Restriction enzymes cut DNA into fragments at specific base sequences in each sample

3. a fluorenscent marker blinds to a triplet in the DNA fragments, so that results can be seen

4. Samples are added to a gel electrpphoresis chamber. Electric current is passed through, pushing the fragments along

5. Heavier fragments stay closer to the origin and smaller fragments go further

6. a banding pattern shows up for each DNA sample and can be compared

What is PCR (polymerase chain reaction) used for?

-copy and amplify tiny quantities of DNA. Very useful if you only have a small sample of DNA (like from a blood sample from a patient or a crime scene) and you need lots of DNA to do DNA profiling.

Which electrode (positive or negative) will DNA travel towards in gel electrophoresis? Why?

positive electrode; DNA is negatively charged (think of all of those phosphate groups!). Note that if the electrodes are not labelled in a gel

4.4.5 Analyse DNA profiles to draw conclusions about paternity

or forensic investigations.

From i-Biology

From Senior biology Book

Microsatellites(short tandem repeats): repeating sequences(2-6 base pairs)

Because noncoding nucleotide sequences repeat throughout the genome, the finding of repeating sequences(DNA profiling) is possible.

4.4.4 Describe the application of DNA profiling to determine paternity and

also in forensic investigations.Organisms have short sequences of bases which are repeated many times. These are called satellite DNA. These repeated sequences vary in length from person to person. The DNA is copied using PCRand then cut up into small fragments using restriction enzymes. Gel electrophoresis separates fragmented pieces of DNA according to their size and charge. This gives a pattern of bands on a gel which is unlikely to be the same for two individuals. This is called DNA profiling. DNA profiling can be used to determine paternity and also in forensic investigations to get evidence to be used in a court case for example.

http://en.wikipedia.org/wiki/DNA_profiling

http://i-biology.net/ibdpbio/04-genetics-and-genetic-engineering/genetic-engineering-and-biotechnology/

http://flashcarddb.com/cardset/14805-ib-4-4-genetic-engineering-and-biotechnology-flashcards