5.20 - Cloned transgenic animals

- animals that are cloned are genetically identical 
- transgenic refers to an organism with DNA from 2 or more organisms 


- commercial production of antibodies 


-cow - obtain egg cell 
- human - take a cell - using restriction enzymes, going to take the 'gene antibody production' 


1. in the egg cell - first step is to knock out the cow antibody production gene 
2. Add human gene - transfer from human cell
3. Cows cell is then developed by mitosis to form a clone of cells - embryo - transferred to the surrogate mother 
4. These then produce genetically identical calves 


In this example, the gene for antibodies is expressed and the antibodies are then collected in the milk - this is the human antibody not cow - large commercial scale

5.19 - Mammal Cloning

sheep 1 = Original --genetically identical to clone--> dolly 


- need to obtain genetic info from 1. - done by removing a diploid cell (has a full set of genetic information) 
- at the same time - need to obtain a cell that has a tendency to divide 
sheep 2. completely different animal - has been treated with hormones to produce eggs 
- egg cell - tends to divide 
- do not want the genetic information of the egg and so it is removed (enucleated) 


- take the cell with the genetic information (want to copy) and the cell from the egg which wants to divide and FUSE them together 
- when fusing them together we have the genetic information and a cell that wants to divide 
- the combination of the two results in many cell divisions (like mitosis) to form a ball of cells (blastula - embryonic sheep - genetically identical to sheep 1) 


-embryo (blastula) of sheep 1 is placed into another sheep 3 - which is the surrogate mother 
- the embryo will grow into a fetus 
- this fetus is the clone of sheep 1 and is what we call dolly - it is genetically identical to sheep 1 
- this means they are a clone, even though their age is very different 

5.18 - Commercial plant growing

- Plant has characteristics which are considered commercial so therefore desirable and so want to make copies of this plant 


- sexual reproduction causes loss of qualities that make it valuable as a commercial plant 


- use a cloning technique to get many plants of the same quality
- commercially, that keeps the product the same so that they can be sold
- technique used is micropropagation 

5.17 - Micropropagation

Looking for characteristics of a plant that are desirable - want to produce more plants of the same kind 


if sexual reproduction - the offsprings will differ and so we have to use micropropagation


Process: 
- Take tissue from the shoot tip or the roots 
- Aseptic conditions (free from contamination) 
- Cut the tissue into many small parts 
- Transfer tissue to petri dish - contains nutrient agar - variety of minerals, rooting compounds and other plant hormones - to encourage growth into small clones of original plants 


- In this process you make many clones of the original plant - all genetically identical to the original plant 

5.16 - Transgenic Organism

- video 5.13: Bacterial cell became transgenic because it had the bacterial DNA and Human DNA (plasmids held Insulin gene)

- this is a transgenic organism 

- video 5.15: Maize DNA and transferred into it was the BT gene 

- this is a transgenic organism 

5.11 - Breeding Animals

- Animal: cow 

- desired characteristic: milk yield 

- the farmer would collect all the milk but take the cows that produce 150ml to be the breeding cows in the next generation

- the farmer then selects the cows with high yield to become the breeding cow in the next breeding population 

- as we progressively select, we are able to change the desired characteristic to develop it - by selective breeding 

- for this to work, milk yield must be genetic (under the control of genes) 

5.10 - Breeding plants

- The number of rice grains is under the control of the genes 

- The farmer wants to increase the number of rice grains per plant to then increase the yield

- The farmer notices that some plants have 6 grains per stem, others have 8 grains per stem and others have 10 grains per stem 

- The farmers decision is to harvest the grains with 6 or 8 but use the 10 grains for planting 

- In the next generation of rice he notices that the grains are increased to 8 grains per stem, 10 grains per stem and 12 grains per stem and so he harvest the 8 and 10 grains and selects the 12 grains for planting and breeding 

- In this way, the number of grains of rice found on the plant will gradually increase which will increase the yield 

- This is an example of selective breeding

5.12 - Restriction and Ligase enzymes

1. Restriction enzymes 

- able to cut DNA at a particular location 

- this location is identified by the base sequence 

2. DNA Ligase

- able to join the DNA back together

5.15 - Genetically Modified Plants

1. Maize - damaged by the larvae of the European Corkborer - can cause up to 20% loss of crop yield 

2. Existence of a bacterium - BT 

- chromosome of BT shown - on the chromosome there is a gene

- when this gene is switched on it produces BT toxin - known to kill the Corkborer larvae. 

3. First step to get the toxin into the Maize to protect it from the European Corkborer 

- take restriction enzymes to the gene of the BT - take the gene out to leave the BT gene for the toxin 

4. Has to be transfered to the cells of the maize plant 

- A 'gene gun' is used to do this - involves taking tiny particles of gold and coating them in the BT gene 

- They are then fired at high velocity at the plant cell 

- This introduces them into the plant cells interior 

- The plant cell then gets the gene 

- Maize cell now has BT gene so when it is switched on it can make the BT toxin which means they can kill the larvae

- This gives the Maize resistance to damage caused by the cork borer

5.14 - Humulin

- Humulin - Human Insulin 

- Bacterial cell (e.g. E Coli) has been transformed by the addition of recombinant DNA 

- culture (large population) of the bacterial cell would be injected into the fermenter 

- the fermenter must provide the culture with nutrients, control of temperature, pH and the gases inside the fermenter

- by creating the optimal temperature for bacterial growth - you will see the population increase 

- the Bacteria switches on the gene for insulin and manufactures the protein Insulin from the provided Amino acids (in the nutrients)  

- then the product must be removed for purification - downstream processing (for human use) 

- the genetically engineered human insulin is called Humulin

5.13b Hosting recombinant DNA

- Recombinant DNA (human gene and Bacterial Plasmid) 

- transfer this structure to the host cell (virus) 

- inside the virus - nucleic acid (e.g. DNA or RNA) 

- around the virus - protein shell (capsid) 

- first thing - remove the nucleic acid from the virus to leave the capsid

- The plasmids are taken up by the virus. The virus acts as a vector for the recombinant DNA 

- This helps to transfer the DNA into the host cell 

- This virus is known as a phage (infects bacterial cells) 

- able to attach to the cell membrane of the bacteria and insert the recombinant DNA into the host cell

- at the end of the process: Bacterial cell which contains the recombinant DNA (including the human gene, insulin) 

- The bacteria has its own DNA plus the DNA from another organism - this combination is known as 'transgenic' 

5.13a - Recombinant DNA

1. Plasmid 

- found in bacterial cells 

- ring of DNA, particularly small and don't carry very many genes 

2. Virus 

- has a protein shell (caspid) 

- inside - nucleac acid - DNA or RNA

- does not have any other structures such as nucleus, cytoplasm

3.  Human Chromosome 

- made of DNA 

- shown gene  is Insulin - Hormone that controls blood sugar levels

- Restriction enzyme is selected so that it can cut the DNA  and take out the Insulin

- having cut the gene --> take the plasmid and cut it with the same restriction enzyme (so it is the same jagged shape) 

- the ring structure is now broken 

- introduce into the cut plasmids, the human insulin gene 

- both the plasmid and the insulin is composed of DNA 

- plasmid then has the insulin in it 

- To complete the process DNA ligase must be added to join the DNA 

- This process of the Human gene and the plasmid DNA is known as Recombinant DNA