5.15- Genetically Modified Plants

Evaluate the potential for using genetically modified plants to improve food production (illustrated by plants with improved resistance to pests)

1. Maize is damaged by the larvae of the european corkborer which can lead to up to 20% crop yield
2. The bacteria Bt has a gene which produces Bt toxin gene which kills the corkborer larvae
3. First, take the restriction enzymes to chop the Bt toxin gene out
4. It is then transferred to cells of the maize plants however it is not easy and gene gun is the technique
5. This involves taking tiny gold particles which are coated with Bt gene. These are fired at a high velocity introducing the gene to the interior of the plant cell
6. This means that the maize gets the gene and can now kill the larvae
7. This gives the maize resistance and increases yield

5.14- Humulin

Understand that large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter

• A culture of the bacteria will be injected into the fermenter
• Nutrients need to be provided 
• Gases, pH and temperature need to controlled
• By creating the optimal temp. --> population will increase and the bacteria will manufacture the protein insulin
• The bacteria inside the fermenter will manufacture the insulin protein from amino acids
• Then the product needs to be removed and purification needs to be carried out (downstream processing)
• Genetically engineered human insulin is called Humulin

5.13

Describe how plasmids and viruses can act as vectors, which take up pieces of DNA, then insert this recombinant DNA into other cells

Plasmids:

·         Found in bacterial cells

·         Ring of DNA

·         Small and don’t carry many genes

Viruses:

•          A protein shell known as a capsid
•          Inside, there is nucleic acid- DNA or RNA

Human Chromosome is made of DNA and we will talk about a gene which codes for insulin (hormone controlling blood sugar levels) 

How to form the Recombinant DNA?

1.  .    Restriction enzyme is selected which cut the gene for insulin
2.  .    Then the plasmid will be cut with the same restriction enzyme
3.  .    The human insulin gene is inserted into the plasmid
4.        Then the ligase enzyme is applied to join the DNA
5.      This is now known as a recombinant DNA

After the recombinant DNA is formed:

•          Virus is used as a host cell
•          Nucleic acid is removed from the virus leaving us with an empty shell
•          The plasmids are inserted into the virus which will act as a vector
•          The virus infects bacterial cells and so is able to attach to the cell membrane of the bacteria and insert the Recombinant DNA
•          This will lead to a bacteria containing the recombinant DNA

5.12

Describe the use of restriction enzymes to cut DNA at specific sites and ligase enzymes to join pieces of DNA together

Restriction Enzymes:

• These are used to cut into the DNA at a particular location
• The location where to cut is identified by the base sequence

Ligase Enzymes:

•  These join the DNA together

5.11- Breeding Animals

Understand that animals with desired characteristics can be developed by selective breeding.

Using Cow as an example, the desired characteristic is milk yield.

• Some cows produced 50ml or 150 ml of milk but most cows produced 100 ml
• The farmer will collect all the milk
• The farmer chooses the 150ml milk cows as his breeding cows
• In the next generation, 
• Some cows produce 100ml or 200 ml of milk but most cows produce 150 ml
• He will then select the 200ml cows for breeding

Milk yield must be genetic for this to work. 

5.10- Breeding Plants

Understand that plants with desired characteristics can be developed by selective breeding


The number of rice grains is under the control of genes. The farmer wants to improve the no. of grains per plant and therefore increase the yield.

• The plants have 6, 8 and 10 grains per stem
• The farmer harvests the 6 and 8 stem grains
• The 10 grain stems are planted
• In the next generation:
• The plants have 8, 10 and 12 grains per stem
• The farmer harvests the 8 and 10 grain stems
• But selects the 12 grain stems for planting

The grain of rice plant gradually increases which means the yield has increased. 

5.9- Fish farming

Explain the methods which are used to farm large numbers of fish to provide a source of protein, including maintenance of water quality, control of intra specific and inter specific predation, control of disease, removal of waste products, quality and frequency of feeding and the use of selective breeding

Fish are an attractive product for farmers as they have low fat and high protein. They are efficient at turning their nutrient into fish mass. 

• Fish farming allow us to control the quality of the water, predators and reduce pests/diseases
• By controlling these factors, the yield of fish will increase
• High density of fish--> possibility of fast transmission of disease, pests
• Farmers use antibiotics in some cases which is of concern to human health
• Pesticides might also be used--> harmful to humans