Genetically Modified Plants

Example:

Maize is damaged by larvae of European cork borer --> 20% loss of crop yield.

This can be solved with that existence of Bacterium BT. In the chromosome of BT there is a gene, and when it is switched on it produces BT toxin which can kill cork borer larvae. 

We have to get the Bt toxin into maize to protect it from European cork borer.

1. Take restriction enzyme to the gene of Bt Bacterium and chop this gene out so that we will get the Bt gene for the toxin. 
2.  Transfer it to the cell of the maize plant. The technique currently being used involved 'gene gon'. --> taking tiny particles of gold coated in Bt genes. They are then fired at high velocity at the plant cell, introducing the Bt gene to the interior of the plant cell. 
3. So the plant cell gets the gene and the maize cell have the Bt gene which make it toxin when switched on --> kill larvae. 
4. This gives the maize resistance to damage caused by the cork borer.

credits to Michelle Huang

5.14 Humulin

The bacterial cell containing the recombinant DNA with the human genes (in this case the production of insulin) can be injected into a fermenter.

In this fermentor chamber we need to consider:

• -Nutrient  - (Used to manufacture insulin protein) 
•  Temperature - (Optimal temperature for bacteria growth ->Increase in population where the bacteria will then switch on the gene for insulin and manufacture protein insulin. )
•  pH
•  Gases 

It will then be necessary to remove the product and carry out purification ( downstream processing)

Genetically engineered human insulin is called Humulin.

5.13 Recombinant DNA

Recombinant DNA

Plasmids are find in bacterial cells and are a ring of DNA and are particularly small carrying little DNA.

Viruses have a protein shell called a capsid and inside there would be a Nucleic acid (of which contains either DNA or RNA).


The human chromosome is made of DNA and in our example, we will talk about the gene which codes for the production of the protein, insulin (hormone controlling blood sugar levels).

1. The restriction enzyme would be selected to cut the DNA, leaving us with the gene of insulin separately.
2. Having cut the gene, the plasmid will also be cut with the same restriction enzyme.
3. This leaves the plasmid ring structure broken, the human insulin gene is then inserted into the plasmid.
4. This will leave our plasmid with the human gene inserted and is then necessary to apply ligase enzyme which will join the DNA.
5. This combination of the human gene, and the plasmid is known as recombinant DNA.

Hosting Recombinant DNA 

1. After the recombinant DNA is formed, it is necessary to find a host cell for it. In this instance, we will use the virus to achieve this.
2. We have to remove the nucleic acid from the virus, leaving us with the capsid of the virus alone.
3. The plasmids are taken up by the virus and the virus will act as a vector of the recombinant DNA.
4. It will help us transfer that DNA to our host cell, the virus known as a phage infects bacterial cells, and so the virus is able to attach to the cell membrane of the bacteria and insert the recombinant DNA into our host cell.
5. At the end of this process, we will have a bacteria containing the recombinant DNA including the human DNA for insulin

Credits to daniel lo

5.12 Restriction and Ligase Enzymes

A restriction enzyme is able to cut DNA at particular location. Location is identified by the base sequence of DNA molecule - very important tool in biotechnology and genetic engineer. 

A DNA Ligase is able to join the two DNA together. 

5.11 Breeding Animals

Example of Breeding animals : cows


 The desired outcome for the cow is the milk yield.

1.  The earliest farmers would realise a few cows would be producing 50 ml of milk, while some produces 150 ml of milk - roughly  most of the cows would be producing 100 ml of milk.
2. The farmer will then collect all the milk and he will only choose cows which produce 150 ml milk as the breeding cows. 
3. In the next generation we find that a few cows are producing 100 ml, a few cows are producing 200 ml and the majority of cows will be producing 150 ml of milk.

He will then repeat the same method selecting the cows which produce 200 ml milk as the breeding cow. And in the next generation there would be a few cows producing 150 ml of milk, a few producing 250 ml of milk and the majority producing 200 ml of milk.

So as we progressively select, we change the desired characteristic. We are able to develop the desired characteristic by selective breeding. 

5.10 Breeding Plants

• The number of rice grain per rice is under the control of genes - The farmer wants to increase the number of rice grain per plant to increase the yield. 
• Some plants have 6 grains per stem, while others have 8 and 10 grains per stem 
• The farmer's decision is to harvest the grains with 6 and 8 grains, but will use those with 10 grains for planting. 

In the next generation of rice, the grains increase to 8-10-12 . The farmer will then harvest those with 8 and 10 grains, but selective those with 12 grains for planting and breeding.

In this way, the number of grains of rice which are found on  these plants gradually increases. This causes the increase in yield. 

This is an example of selective breeding.