Genetics3.5 Genetic modification and biotechnology

Electrophoresis• Gel electrophoresis is

used to separate proteins or fragments of DNA according to size.

• DNA is negatively charged.

• Proteins can be neg or pos charged.

• Eukaryotic DNA must be broken into smaller fragments.

• Exposed to electric field.

• Gel resists movement▫ Smaller DNA segments

move further.

DNA amplification by PCR• PCR can be used to amplify

small amounts of DNA• Many copies made in a short

period of time• Copy specific DNA sequences

not the whole genome▫ Selected by using a primer that

binds to the start of a desired sequence

• Only a small amount needed to start.▫ Why would this be important?

Forensics Fossils

• Data-based question p 188

DNA profiling• DNA profiling involves

comparison DNA• Sequences that are known to

vary considerably between individuals are selected and copied. ▫ Why?

• Copied DNA is cut into fragments with restriction endonucleases (enzymes).

• Fragments separated using gel electrophoresis

• Pattern of bands = DNA profile

Who dunnit?

See Example: page 190

Who is the Daddy?

Genetic Modification

• Genetic modification = The transfer of genes from one species to another▫ Possible because the genetic code is universal

Same amino acid sequence translated Same proteins produced

• Examples: ▫ Producing human insulin using bacteria (see 2.7)▫ Introducing new characteristics to animal species:

goats with spider silk protein in milk.▫ New varieties of crop plants (GM): tomatoes that are

purple.

Genetic engineering• Genetic engineering

= the collective term for the techniques used to transfer genes from one species to another.

• Gene tranfer to bacteria with plasmids using restriction endonucleases and DNA ligase.

Genetic engineering

•Usually easier to obtain mRNA transcripts of genes

•Reverse transcriptase is an enzyme that can make DNA (called cDNA) from RNA

Assessing the risks of genetic modification•Almost everything we do carries risk.•Scientists must assess the risk associated

with their research before carrying it out.▫What is the chance of an accident or other

harmful consequences?▫How harmful would the consequences be?

•Discuss•See p 194 and Data-based question p 195

Clones• Clones: groups of genetically identical

organisms, derived from a single original parent cell.

Natural Methods Human involvmentAsexual reproductionGarlic bulbsStrawberry plantletsHydra buddingAphidsTwins

Plant cuttingsSplitting embryosTransplanted nuclei

Dolly• Activity:

http://teach.genetics.utah.edu/content/tech/cloning/Youve%20Come%20A%20Long%20Way%20Dolly.pdf

• Video: https://www.youtube.com/watch?v=tELZEPcgKkE

• See p 199

Cloning simulation

•http://learn.genetics.utah.edu/content/cloning/clickandclone/