Genetic Engineering and Biotechnology

IB Topic 4.3

Exploring DNA

• DNA is at the very core of what gives animals and plants their uniqueness

• In this topic, we are going to look at the genetic techniques developed in the past few decades which enable scientists to explore and manipulate DNA

These include:

• Copying DNA in a lab • Polymerase chain reaction (PCR)

• Using DNA to reveal its owner’s identity• DNA profiling

• Mapping DNA by finding where every A, T, C, and G is • The Human Genome Project

• Cutting and pasting genes to make new organisms • Gene transfer

• Cloning cells and animals

What’s the big deal?

• These techniques offer (just to name a few): • New hope for obtaining treatments and

vaccines for diseases• Creating new plants for farmers• Freeing wrongly convicted people from

prison

Some techniques have sparked debate & controversy

• Gene transfer & cloning• Is it morally and ethically acceptable to

manipulate nature? • Is it morally and ethically acceptable to

create human embryos for scientific research?

• Big biotech companies – helping society or out to make money?

How does this affect YOU?

• Part of being a responsible citizen is making informed decisions relating to difficult questions. • IB learner profile

• It’s not just the technical complexity that makes these questions difficult, it’s also because humans have never had to face them before.

Polymerase Chain Reaction (PCR)

• PCR is a lab technique which takes very small quantities of DNA and copies all the nucleic acids in it to make millions of copies of the DNA

PCR • PCR allows scientists to get enough DNA

from a sample to be able to analyze it• Collecting DNA from a crime scene or a

cheek swab often have a limited number of cells to work with • PCR allows scientists to makes millions of copies

of the DNA in a few hours • Such quantities are large enough to get results

from other tests (like gel electrophoresis)

YouTube Video – PCR

• http://www.youtube.com/watch?v=lf4ztsko1xY&feature=related

Gel Electrophoresis

• Lab technique used to separate fragments of DNA

• What’s the purpose? • Done in effort to identify its origin

How does gel electrophoresis work?

• Enzymes chop up long filaments of DNA into varying sized fragments

• The fragments are placed into small wells (holes) in gel • Aligned along one end

• The gel is exposed to electric current• Positive on one side, negative on the other

Gel electrophoresis continued

• What’s the effect? • The biggest, heaviest and least charged particles

do not move easily through the gel• They stay relatively close to the wells

• The smallest, least massive and most charged particles pass through the gel to the other side with little difficulty

• Intermediate particles are distributed in between • In the end, the fragments have a banded

pattern

The results …

• Analyzing the banding pattern can be used in DNA profiling