Experiment 2.32 Energy Content of Food

Recall how to carry out a simple experiment to determine the energy content in a food sample

Equipments:

Thermometer

Boiling Tube (filled with 20cm^3 of water)

Crucible --> measured mass of food sample 

Record initial temperature of water in Celsius, for example, 20C.

The food source is ignited and there is a heat transfer from the food source to the water. When the food is completely combusted, we then record the final temperature of the water, for example 30C. 

1 cm^3 of water has a mass of 1 g. 

1 cm ^3 of water, to raise its temperature by one degree takes 4.2 J. 

Calculation:

(mass of water (g) x temperature rise (C ) x 4.2)

Energy released from food per gram = ------------------------------------------------

mass of food sample (g)

= [20 x (30-20) x 4.2] / 10

= 84J / g

Cloning

1. An egg cell was removed from the ovary of an adult sheep B The egg cell's nucleus is then removed. 
2. Nucleus from the organ cell, for example udder cell, of adult sheep A is the taken out and inserted into the empty egg cell. 
3. The fused cell has complete set of chromosome and began to develop normally (in the lab) using genetic information from the donated DNA. 
4. Before the dividing cells specialize, the embryo is implanted into the uterus of a surrogate mother sheep C. The offspring is genetically identical to sheep A. 

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)

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. 

So the plant cell gets the gene and the maize cell have the Bt gene which make it toxin when switched on --> kill larvae. 

This gives the maize resistance to damage caused by the cork borer.

5.14 Humulin

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

The transgenic bacterial cell has been transformed from normal bacterial cell by the addition of recombinant DNA (plasmid + human gene for insulin).

A culture of bacteria will be ingested into the fermentor.

In this fermentor chamber we need to consider:

- Nutrient --> Used to manufacture insulin protein 

- Temperature --> Optimal temperature 

- pH

- Gases 

----> Increase in population, in which the bacteria will then switch on the gene for insulin and manufacture protein insulin. 

It will then be necessary to remove the product and carry out purification

Purification = Downstream processing 

Genetically engineered human insulin = Humulin

5.13 Recombinant DNA

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

Plasmids (circular structure) are found in bacteria cell, which are a right of bacteria DNA (as bacterias are prokaryotes and do not have proper nucleus). They are particularly small and don't carry many "information". 

Essentially, a virus has a protein shell called a capsid (pentagonal structure). Inside there will be a nucleic acid, possibly DNA or RNA. The virus has no other cellular components, such as cytoplasm or nucleus. 

A human chromosome (long threadlike structure) is made out of DNA.

Genes are section of chromosome.For instance, a gene is responsible for insulin, or hormone controlling blood sugar level. 

1. The restriction enzyme is selected that can cut the DNA of the section which made up the gene for insulin. 

2. Having cut the genes, we will take the plasmid of bacteria and cut it with exactly the same restriction enzyme. (Human enzyme that cuts out the human gene also cuts out the plasmid.) This will leave a broken ring structure. 

3. Introduce into the cut plasmid the human insulin gene. Both plasmid and human genes are composed of DNA. The human gene is then inserted into the plasmid. 

4. Complete the process by applying DNA Ligase enzyme to join the DNAs together. This combination of human genes + plasmid is known as recombinant DNA. 

Hosting Recombinant DNA 

(way in which recombinant DNA is transferred into other cells)

It is necessary to transfer the recombinant DNA into the host cell. In this instance we will use the virus. Inside the virus is the nucleic acid such as DNA or RNA. Around it is the protein.

1. Remove nucleic acid from the virus. We only want the capsid protein shell. 

2. The plasmid are taken up by the virus. The virus is going to act as a vector of the recombinant DNA, which will transfer it into the host cell.

The reason why we have chosen virus is that the virus is known as a phage, and it infect bacterial cells. The virus is able to attach to the cell member of the bacteria and insert the recombinant DNA into the host cell. 

At the end of this process we have a bacterial cell which now contains the recombinant DNA including the human gene for insulin. 

Notice that the bacteria still has its own normal DNA plus DNA from another organism. This organism is known as transgenic. 

5.12) Restriction and Ligase Enzymes

Describe the use of restriction enzymes to cut DNA at specific sites and ligame enzymes to join piece of DNA together. 

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

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

5.11 Breeding animals

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

Cow ---> Desired character = milk yield

Earliest farmers noticed that a few cows (A) would produce a small amount of milk each time, for example, 50 ml. A few other cows (B) would produce a 150 ml of milk. Most © would be producing a 100ml of milk.

The farmer will collect all the milk, but it would be cows C that he would choose to become his breeding cows. 

In the next generation of cows, we find that a few cows are producing 100 ml, a few with 200 ml (D) , and most with 150 ml of milk. 

The farmer then will select cows (D) as his breeding cows. 

Cows that produce high yield becomes the breeding population --> selected for the desired characteristic.

In the 3rd generation, it would be ranged with 150 --> 200 --> 250. 

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

For this to work, recall that milk yield must be under the control of genes (genetic).