Genetic engineering modelling the process 1 Find the

Genetic engineering: modelling the process

1. Find the gene for the desirable trait 1. Cut around the model DNA from your sheet and secure in two circles

The gene for the desirable trait is the CRY gene, which produces a protein with insecticidal properties. It is found in the bacterial chromosome of Bacillus thuringiensis.

Bacterial chromosomes are circular, so to model it you will cut on the dotted line around the model chromosome from Bacillus thuringiensis and secure it in a circle using sticky tape.

A vector (DNA molecule used to carry foreign DNA into another cell) is needed to introduce the gene for the desirable trait from Bacillus thuringiensis into another cell. We will use a plasmid from Agrobacterium tumefaciens.

Plasmids are loops of DNA in bacteria, so to model it you will cut on the dotted line around the model plasmid from Agrobacterium tumefaciens and secure it in a circle using sticky tape.

2. Isolate the gene using enzymes 2. Cut at the ‘restriction enzyme’ sites in a zigzag leaving ‘sticky ends’

Restriction enzymes recognise specific DNA sequences and cut them in a predictable way like a pair of molecular scissors. Bam. HI is a restriction enzyme that cuts the DNA sequence GGATCC leaving 4 bases of single stranded DNA.

You need to cut the restriction enzyme sites shown on your model DNA using scissors to leave the 4 bases of singlestranded DNA known as ‘sticky ends’.

3. Insert the gene into a plasmid vector from a plant bacteria, making recombinant DNA 3. Stick the DNA fragment with the gene of interest into the open plasmid (base pairing along ‘sticky ends’) using sticky tape

Plasmid from Agrobacterium tumefaciens Gene encoding the insecticidal protein from Bacillus thuringiensis Recombinant DNA is two strands of DNA joined together. Another enzyme called ligase is used to ligate (stick) the gene for the desirable trait into the plasmid vector.

Plasmid from Agrobacterium tumefaciens Gene encoding the insecticidal protein from Bacillus thuringiensis You will use sticky tape to do play the role of ligase and join the model DNA with the gene for the CRY protein into the model plasmid, making recombinant DNA.

4. Insert the recombinant plasmid vector into the plant bacteria, making the plant bacteria genetically modified 4. Take this paper model of your recombinant plasmid and put it into a yoghurt pot (representing the plant bacteria)

The process of inserting a vector into a bacteria is known as transformation.

The plasmid will be coiled as it enters the bacterial cell through the cell membrane.

5. Mix genetically modified plant bacteria and plant cells. The gene for the desirable trait will transfer into some of the plant cells, making them genetically modified. 5. Try to throw the paper model of your recombinant plasmid from your yoghurt pot (plant bacteria) into the box (plant cell), transferring the gene of interest into the plant.

The plant bacteria Agrobacterium tumefaciens transfers the plasmid vector into the plant cell, making a genetically engineered plant cell, in which the gene for the desirable trait will be expressed.

This system for introducing genes for desirable traits into plants is a bit lengthy, but has a high success rate.

6. Grow these plant cells on nutrient agar, then the plantlets in soil, to create genetically modified crop plants. How many genetically modified plant cells did your class successfully create by modelling the process of genetic engineering?

Genetic engineering: modelling the process