End of Notes

All aspects of the Biology specification (both paper one and two) has been covered. (Yay!).
Good luck!

5d) Cloning

Cloning plants using tissue culture:

1. Plant with desirable characteristics is selected to be cloned. Small pieces (explants)are taken out from the tips of the stem and the sides of the shoot
2. They are then sterilised to kill any bacteria
3. The explants are then grown in vitro - placed into a petri dish containing a nutrient medium (agar) Has all the nutrients to help it grow and austin hormone
4. Cells in explant divide and grow into a small plant
5. Small plant is taken out of medium and planted in the soil and put into greenhouses so they share the same characteristics as the original 
6. There is agar jelly inside which has nutrients (NPK, Mg, Ca, S and Auxin hormones) to help the cells to divide and grow
7. Can be used to produce commercial quantities of identical plants 

Cloning an adult mammal (dolly the sheep):

1. A body (somantic) cell of Sheep A is taken out as it is the sheep we want to clone and the nucleus is taken out (enucleated) and kept 
2. Then the egg cell of another sheep, Sheep B is taken out, because egg cells can adjust and differentiate (change into different types) and then the nucleus is taken out and thrown away 
3. Nucleus of Sheep A is put into the egg cell of Sheep B
4. This egg cell works like a normal fertilised egg and when it is stimulated with an electric shock it divides (by mitosis) and forms an embryo
5. Once it forms a small embryo it is inserted into the uterus of a different sheep, Sheep C- with a different phenotype to prove that the cloning worked
6. The embryo developed normally and was born as a Clone of the first sheep (A). 

Paper Two- Pros and Cons:

Pros-

Help cure diseases by transferring genes into food and giving it to people 

Could make it possible to have organ transplants by cloning organs 

Useful genetics are passed on to offspring 

Cons-

Cloned animals might not be as healthy as normal ones 

Might be consequences that we're not aware of

5c) Genetic modification/engineering

Restriction Enzymes - Are used to splice (cut) the DNA at the specific site- desired gene, e.g. human insulin. It can either be cut as a blunt or sticky end.

Ligases Enzymes - are used to stick pieces of DNA together

Vectors- something to transfer new DNA:
e.g. plasmids and viruses
Plasmids -

1. Isolate/ take out plasmid from bacterium using a pipette
2. cut apart the plasmid 
3. splice out the required gene using enzymes 
4. The glue using ligases the required gene and plasmid together. This is then called RECOMBINANT DNA. 
5. TRANSGENIC CELLS multiplies and starts producing (e.g. human insulin)  

Viruses-

1. Spice the required gene 
2. Add to the virus
3. Virus injects into the DNA (new organism) and RECOMBINANT DNA forms 
4. You then have a transgenic bacterium

Large amounts of human insulin can be produced by genetically modified bacteria that are grown in a fermenter 

Genetically modified plants:

• Crops can be genetically modified to increase food production in lots of different ways - one way is to make them resistant to insects, another is to make them resistant to herbicides (chemicals that kill plants) 
• Making crops insect-resistant means farmers can spray as many pesticides so wildlife isn't destroyed. It also increases crop yield. 
• Making crops herbicide-resistant means farmers can spray it to kill weeds but not the crops
• Some people are against genetic engineering altogether as they worry that a change in organisms genes might create unforeseen problems

1. Splice the DNA with desired features using the enzymes 
2. Meanwhile take plasmid out of Bacteria (Agrobacterium tumefaciems) and cut to allow space for the gene 
3. glue it together to make it a recombinant DNA 
4. Add the new DNA into a petri dish
5. There is agar jelly inside which has nutirents (NPK, Mg, Ca, S and Auxin hormones) to help the cells to divide and grow