3.5 Genetic modification and biotechnology Understanding: Gel electrophoresis is used to separate proteins of fragments of DNA according to size PCR can be used to amplify small amounts of DNA DNA profiling involves comparison of DNA Genetic modification is carried out by gene transfer between species Clones are groups of genetically identical organisms, derived from a single original parent cell Many plant species and some animal species have natural methods of cloning Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells Methods have been developed for cloning adult animals using differentiated cells Skills: Design of an experiment to assess one factor affecting the rooting of stem cuttings Analysis of examples of DNA profiles Analysis of data on risks to monarch butterflies of Bt crops Applications: Use of DNA profiling in paternity and forensic investigations Gene transfer to bacteria with plasmids using restriction endonucleases and DNA ligase Assessment of the potential risks and benefits associated with genetic modification of crops Production of cloned embryos by somatic cell nuclear transfer Nature of science: Assessing risks associated with scientific research: scientists attempt to assess the risks associated with genetically modified crops or livestock

Polymerase Chain Reaction (PCR) Amplify small amounts of DNA Just need a single molecule of DNA to make millions of copies Able to study DNA without using up the whole sample DNA from fossils DNA from crime scene (hair, semen or blood) https://www.youtube.com/watch?v=x5yPkxCLads Understanding: PCR can be used to amplify small amounts of DNA

Cover work: Polymerase Chain Reaction (PCR) Answer these questions What are the ingredients for PCR? What are primers? Why must the mixture be heated/cooled to about 95°C? 55-60°C? 72°C? Understanding: PCR can be used to amplify small amounts of DNA

Polymerase Chain Reaction (PCR) 1. Template DNA, DNA primers, Deoxynucleotide triphosphates, thermophilic polymerase with a buffer 2. Primers start the chain reaction 3. 95 = DNA strands separate as hydrogen bonds break 55-60 = Primers bind to single DNA strands 75 = optimum temperature for DNA polyermase enzyme Understanding: PCR can be used to amplify small amounts of DNA

Gel Electrophoresis Separate proteins according to size In an electric field Samples placed into wells in a gel Electrical field applied Charged molecules move through the gel Small fragments move faster than large ones Understanding: Gel electrophoresis is used to separate proteins of fragments of DNA according to size

Cover work: Gel Electrophoresis Go to: http://learn.genetics.utah.edu/content/labs/gel/ Answer the following questions: What is the gel made up of? What is the purpose of the buffering solution that the gel is immersed in? Why are known DNA fragment lengths/size standards needed? How does the gel separate DNA strands of different lengths? Understanding: Gel electrophoresis is used to separate proteins of fragments of DNA according to size

Gel Electrophoresis Powdered agarose, buffer (Jell-o) Salt water solution that allows electrical charges to move through the gel Compare your bands to bands of known length to help you identify the length of DNA DNA moves through gel repelled by negative charge – smaller moves further away Understanding: Gel electrophoresis is used to separate proteins of fragments of DNA according to size

DNA profiling Sample of DNA obtained Sequences selected and copied by PCR Copied DNA split into fragments using enzymes Fragments separated using gel electrophoresis Produces a pattern of bands that is always the same with DNA from an individual Compare profiles of individuals to see which bands are similar or different Understanding: DNA profiling involves comparison of DNA

Compare DNA at a crime scene with suspects DNA

Paternity Tests Men claim they are not the father Mother has multiple partners and isn’t sure Child wishes to prove they are an heir Applications: Use of DNA profiling in paternity and forensic investigations Skills: Analysis of examples of DNA profiles

Genetic Modification Transfer of genes between species Genetic code is universal = amino acid sequences translated from genetic code is unchanged Same polypeptide is produced Understanding: Genetic modification is carried out by gene transfer between species

Genetic Modification Gene for making human insulin to bacteria Goats produce milk that contains spider silk Many GM crops Understanding: Genetic modification is carried out by gene transfer between species

Salmon grows twice as fast Genetic Modification Salmon grows twice as fast Understanding: Genetic modification is carried out by gene transfer between species

Bananas that contain a vaccine for a disease Genetic Modification Bananas that contain a vaccine for a disease Understanding: Genetic modification is carried out by gene transfer between species

Genetic Modification Cows with 25% less methane Less impact on the environment Understanding: Genetic modification is carried out by gene transfer between species

Involves the use of plasmids, DNA ligase and restriction endonucleases Gene Transfer Involves the use of plasmids, DNA ligase and restriction endonucleases Applications: Gene transfer to bacteria with plasmids using restriction endonucleases and DNA ligase Understanding: Genetic modification is carried out by gene transfer between species

Ligase sticks end together Restriction enzymes cut both gene and plasmid (produce the same ‘sticky ends’) Ligase sticks end together

Multiply bacteria containing gene

Separate and purify human insulin Human insulin can then be used by diabetic patients

Finish off... PCR questions Gel Electrophoresis questions Check your cuttings experiment - is anything happening yet? Kognity topic 5 questions Next lesson is topic 10 (HL)

What is a clone? A clone is genetically identical to its “parent” (single original parent) Understanding: Clones are groups of genetically identical organisms, derived from a single original parent cell

Types of reproduction SEXUAL Genetically different offspring ASEXUAL Genetically identical offspring Understanding: Many plant species and some animal species have natural methods of cloning

Sexual Reproduction HUMANS GAMETES Sperm cell: Egg cell: Each gamete contains 23 single chromosomes Half the number of that in a normal cell (23 pairs) These are haploid cells Understanding: Many plant species and some animal species have natural methods of cloning

Sexual Reproduction FERTILISATION Gametes fuse together Form a cell with 23 pairs of chromosomes This is a Diploid cell Offspring inherits features from both parents Variation in offspring

Advantages: Sexual Variation in offspring means they are able to Adapt to surroundings Evolve Understanding: Many plant species and some animal species have natural methods of cloning

Asexual Reproduction An ordinary cell can make a new cell by dividing in two New cell has exactly the same information as parent cell No fertilisation between male and female gametes Some plants and bacteria produce offspring asexually (some animals do too when no males around) Understanding: Many plant species and some animal species have natural methods of cloning

Advantages: Asexual Very quick Bacteria can produce offspring in 20 mins If already adapted to habitat – good to be identical Understanding: Many plant species and some animal species have natural methods of cloning

Break up embryo into more than one group of cells Embryos Break up embryo into more than one group of cells All cells in an early animal embryo are able to develop into any type of tissue Understanding: Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells

Cloning Animal Embryos Sometimes this happens naturally Can also be done artificially Understanding: Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells

Able to ensure they have desired characteristics Cloning Adults Harder than cloning embryos as cells have already differentiated into different tissue cells Able to ensure they have desired characteristics Understanding: Methods have been developed for cloning adult animals using differentiated cells

Dolly the Sheep Applications: Production of cloned embryos by somatic cell nuclear transfer

A tale of somatic cell nuclear transfer Dolly the Sheep A tale of somatic cell nuclear transfer

What’s a somatic cell???

Normal body cell Diploid nucleus 23 pairs of chromosomes

Her name is not important Once upon a time… There was a Finn Dorset Ewe Her name is not important

Cells were taken from her udders These were grown in a lab

Genes made to become inactive No longer on a path of differentiation

Then we meet the Scottish Blackface Ewe Unfertilized eggs taken from her ovaries, nucleus removed

So we have these two types of cells Udder cells with inactive genes Unfertilized egg cells with no nucleus

10% of fused cells turned into an embryo Electric pulse used to fuse the two cells together 10% of fused cells turned into an embryo

7 day old embryos injected into surrogate mothers ewes 1/29 was successful

(with the one with the udders) Dolly was the spitting image of the Finn Dorset Ewe (with the one with the udders) THIS WAS DOLLY

Plant cuttings experiment Investigating factors affecting the rooting of stem cuttings: in groups Short lengths of stem that are used to clone plants artificially Roots develop from stem = independent new plant Design your experiment which we will complete next time we are in a lab Hypothesis and explanation Independent variable, dependent variable, control variable Method What could your independent variable be? Length of stem How many leaves Size of leaves Water or compost Cut above or below node Temperature of air Plastic bag over cuttings Skills: Design of an experiment to assess one factor affecting the rooting of stem cuttings