On a side note, I don’t know DNA can also be found from food.

(ii) PCR:
Polymerase chain reaction is a technique widely used in molecular biology to amplify DNA to make millions, millions and millions of its copies, forming one super big DNA family tree. PCR is an endless process that involves three steps,  denaturation, priming and extension to separate and replicate 2 strands of DNA.

One important thing is that we need to use a “heat-loving” bacteria (Thermus aquaticus) for PCR in order to survive the “denaturation” process, as most DNA polymerases that resides in our body are burned to death at temperatures below 95°C (We humans will also decomposed into tiny ashes, so…). The heat-loving Thermus aquaticus possess its own unique “superpower” that can survive at temperatures near the boiling point of water (Denaturation temperature is at 94°C). 

 

(iii) Gel electrophoresis:
This step is a continuum from the PCR, where DNA fragments are isolated and inserted into cloning vectors. DNA molecules in gel electrophoresis are placed in a gel (often made of agarose) in the electrophoresis chamber that filters the DNA fragments by size and slows down the movement of DNA. Smaller DNA fragments move faster than its larger (or fatter) siblings, thus they travel farthest up the agarose gel. This helps to identify the DNA fragment patterns of individuals, which is used widely in forensics to rat out criminals in crime investigation cases.

1. Make the gel
2. Set up the gel apparatus 
3. Load the DNA sample into the gel 
4. Hook up the electrical current and run the gel 
5. Stain the gel and analyse the results 

(i) DNA Extraction:

(ii) PCR:

(iii) Gel Electrophoresis:

2. PCR: make multiple copies of the desired DNA part for diagnosis, identification, criminal matching ... Involves

https://goo.gl/images/9CGcWK

3. Gel electrophoresis: use of an electric field to separate DNA mixture into individual strands for analysis (eg. DNA evidences in crime scene) 

https://goo.gl/images/a3wuV4
https://goo.gl/images/gf6QRX 

iii)Gel Electrophoresis:

It is a 5 steps experiment to sort  DNA according to their length using electrical current. DNA moves as it repelled by negative end. Shorter DNA strands will move farthest away. DNA with same length will move at same speed and group together at the end.

The purpose of it is for genetic testing, body identification and analysis of forensic evidence. DNA extraction is crucial because DNA needs to be properly purified away from proteins and other cellular contaminants.
Lysis solution contain detergent that will disrupt cell membrane and nuclear envelope, burst the cell and release DNA. Presence of proteinase K enzyme cuts apart histones to free DNA. Salt in this experiment clump protein and cellular debris together.
     2.    PCR
PCR is to make more DNA copies. The DNA from PCR can be extracted from cells: blood, skin, saliva or hair follicles. The primer is the powerful tool to copy specific DNA sequences. The temperature and timing in the DNA thermal cycle is vital.  At 95 °C, DNA helix separates into 2 single strands. Then cooled down to 50°C, primer attach to DNA strands, thus strands are unable to rejoin. 72°C, DNA polymerase activated.
     3.   Gel Electrophoresis
Purpose is to sort and measure DNA strands. As electrical current is activated, shorter strands will move quicker than longer strands. Over time, short strands will be located away from starting point. DNA strands of same length will then grouped together.

In order to separate DNA from proteins and debris, the tube is placed inside a centrifuge, causing heavy clumps of protein and cellular debris to sink to the bottom of the tube while strands of DNA remain distributed through the liquid. A micropipettor is then used to remove the liquid containing DNA and it is placed into a clean tube.

 

2.   PCR

To perform a PCR reaction, we need DNA that has been extracted from cells. Since the purpose of PCR is to make more DNA copies, we do not need a lot of DNA in order to start the reaction. We can extract DNA from a small sample of blood, skin, saliva or hair follicles.

 

3.   Gel Electrophoresis

DNA strands are pushed through the gel filter by “Electrophoresis”. Therefore, we are able to make DNA move by adding electrical current.

DNA is contained in the nucleus of body cell. 
Lysis solution contains detergent and enzyme called proteinase K. This solution is added to it to burst the cell open in order to get the DNA  and to unwrap the proteins wrapping the DNA. The tube is then left in warm water bath for the lysis solution to work on the cell. 

Centrifuge was used to spin the tube at high speed to separate the clump of proteins and cellular debris from strands of DNA. 
Isopropyl alcohol is added to see the DNA with naked eyes .

Purpose of PCR is to make copies of DNA.
Primers were used in this experiment to attach to either ends of the DNA segment where you want to copy. 
Nucleotides are used to make up the genetic code.
Polymerase were added to read the DNA codes and attach them to matching nucleotide.
To make the reactions work, the tube is placed thermal cycler for it to heat and cool at a certain temperature. When heated, the double-helix structure of the DNA breaks into 2 single strands. The primers mark and ‘lock’ the strands from rejoining.
At another temperature, the polymerase reacts by locating the primers and attach nucleotides to it and fall off once it gets to the end of the strand

3. Gel electrophoresis 

This method is a way to measure the length of DNA strands. The gel is like a filter which filters out DNA. DNA samples are placed in the hole at one end of the gel and moves through the filter when electric current is activated. The gel contains salt solution which allows electrical currents to flow in the gel. Short DNA strands move through faster than long DNA strands. Over time, shorter DNA strands will be sorted out from longer strands as they move farther away from long strands and in groups. 
To be able to see DNA with naked eye, staining technique can be applied.DNA length can be seen under UV light (with protective goggles) after adding DNA staining solution. The length of the DNA sample is then compared with the length of the DNA standard to have an estimation of the length of strands from DNA sample. 

Our body cells contains nucleus, which in turn contains DNA strands. Lysis solution is added into the cheek sample which is made up of detergent and an enzyme known as Proteinase K. Lysis solutions aids in causing the proteins that are surrounding the DNA to be opened, so that the DNA can be isolated and extracted. In order for the lysis solution to work on the cell, it has to be placed in a warm water bath. After being placed in the warm water bath, it undergoes a centrifuge which spins the tube at high speeds in order to break apart the protein clumps and cellular debris which comes about from the DNA strands. As the DNA is too small for even the naked eye to see, isopropyl alcohol has to be added in order to see the DNA.

The main aim of PCR method is to make copies of DNA. If you want to copy a particular segment of DNA, you can attach the primers to that particular segment that you want to copy. The genetic code are made up of nucleotides. Polymerase has to be added in order to be able to interpret the DNA codes and match them to the correct nucleotides. 

For the reaction to occur successfully, the tube has to be placed in a thermal cycler for the heating and cooling processes to happen at a certain temperature. As heating occurs, the double-helix structure of the DNA is broken into 2 single strands. The primers lock the nucleotides so that the double-helix can be reformed.

3) Gel electrophoresis

Gel Electrophoresis is one method that can be used in differentiating the different lengths of DNA strands. The gel acts as the filter responsible for sorting out the different DNA strands, as it has small pores.  

To obtain isolated DNA samples, the crucial step is DNA extraction. Firstly, consists of collecting cheek cells by swabbing cheek with a buccal swab. Secondly, bursting cheek cells open to release the DNA by the addition of lysis solution. Thirdly, separating the DNA from proteins and cellular debris by placing solution in a warm water bath followed by addition of concentrated salt solution and then placed into a centrifuge. Lastly, isolating concentrated DNA by adding isopropyl alcohol and placing it into the centrifuge, then dry the DNA to finally obtain a DNA sample. 

PCR generates more identical DNA copies of a specific DNA sequence by utilising DNA that has already been extracted from cells. During the third cycle, desired products will start to appear. Two strands will appear that begins with primer one and ends with primer two. These are just partial segments of the targeted DNA. As the cycle continues, these desired products will then become the majority and at the end of thirty cycles, produces over a billion fragments containing only the target sequence and only sixty copies of the longer molecules. Hence, will have an almost pure target sequence. 

 

Gel electrophoresis helps to measure the length of DNA strands and to do so, involves an electrical field. Electrophoresis is to push DNA strands through the gel filter and add electrical current to move the DNA, sorting out strands that are long and short or of the same length. When electrical current is turned on, the DNA will move to the positive end through repulsion of the negative charge.

After the collection of the cells, lysis solution is added and is placed in a warm water bath. The lysis solution contains detergent which disrupts the cell membrane and nuclear envelop, causing the cell to burst, releasing the DNA. It also contains proteinase K, which cuts apart the histones to free the DNA. Concentrated salt solution is then added, which causes the proteins and other cellular debris to clump together. It is then placed in a centrifuge to allow the clump to sink to the bottom. The DNA solution is separated from the debris and isopropyl alcohol is added. As DNA is not soluble in isopropyl alcohol, it will clump up and come out of the solution. It is then placed in a centrifuge to allow the DNA clump to sink to the bottom. After removing the liquid and drying the DNA, the extraction is complete.

2. PCR
 PCR is used to create billions of copies of a specific DNA sequence. After adding the extracted DNA to the PCR tube, primers are added. Primers attach to either end of the DNA segment that is to be copied. Nucleotides added is used to make the DNA copies. DNA polymerase added reads the DNA code and creates the copies by attaching matching nucleotides. The tube is then placed into a DNA Thermal Cycler, which can precisely heat and cool the tube, which is important for making the reaction work. At a high temperature, the DNA separates. When it is cooled, the primers lock onto its target before the DNA strands can pair up. At another temperature, the DNA polymerase activates, locates the primer, and starts to make the DNA strand. It is repeated for another 2 cycles, after which the desired fragments can be obtained.

3. Gel Electrophoresis
It is a way to sort and measure DNA strands. The gel is the filter that sorts the DNA strands. An electric current is added, which makes the DNA move. This is ‘electrophoresis’, which is how the DNA strands are pushed through the gel filter. The shorter strands move through more quickly compared to the longer strands. The DNA strands sort themselves and when stained, can be seen as bands in the gel. The gel block is then stained with ethidium bromide, which binds to DNA and shows up under fluorescent light. It is then placed on a UV light box, where it is  compared with the standard and estimates are made. The estimated length is in base pairs.

Can be used for genetic testing, body identification and analysis of forensic evidence.

Lysis solution is used to release DNA from cells. It contains detergent which can disrupt the cell membrane and proteinase K which can separate DNA from histones.

Salt solution is used to clump protein and debris that will be remained in the bottom of the tube after centrifuged.

As DNA is not soluble in isopropyl alcohol, we can use isopropyl alcohol to separate DNA from liquid.

2)     PCR 

Polymerase chain reaction is used to copy desirable fragment of DNA strand.

30 cycles can create a billion of fragments.

3)     Gel electrophoresis

Used to sort and measure DNA strands

Also can be used for protein.

Electrical current is used in the test due to the presence of buffer liquid which is a salt water that can allow electrical charges flow through the gel.

Ethidium bromide is used for staining. 

The lysis solution consists of detergent and an enzyme called proteinase K. The detergent disrupts the cell membrane and nuclear envelope, causing the cells to burst open and release DNA. As DNA is still wrapped around histones, proteinase K cuts the histones and release the DNA. Concentrated salt solution causes the proteins and other cellular debris to clump together so it is easier to isolate the DNA via centrifugation.

The thermal cycler heats up to 95 degree celsius where the DNA double helix separates, creating two single-stranded DNA molecules. The temperature lowers to 50 degree celsius so that the primers can lock onto their target before the DNA single strands rejoin. It will then increase slightly to 72 degree celsius where DNA polymerase is stimulated to copy the strand.

The DNA strands are pushed through the gel filter by electrical currents. Shorter strands move through the holes in the gel more quickly than longer strands. Thus, shorter strands in the sample will move further away from the starting point. DNA of the same length will move at same speed and group together.

 
3. Gel Electrophoresis
Gel electrophoresis is used to sort DNA strands according to length and this is also useful for separating other types of molecules such as proteins. The “gel” is the filter that sorts the DNA strands while “electrophoresis” is how we push the DNA strands through the gel filter. Short strands move through the gel faster than long strands.

DNA needs to be purified away from proteins & other contaminants. Step to purify DNA, 

1.Collect cells from the sample. 

2.Burst cells open to release DNA by adding lysis solution and place in water bath. Lysis solution contains detergent and enzyme Proteinase K. 

3.Separate DNA from the proteins and debris by adding concentrated salt solution which causes proteins and cellular debris to clump together followed by centrifuging. 

4.Isolate concentrated DNA by adding isopropyl alcohol and place in centrifuge allowing the DNA to sink.  

Important components added are Primers, DNA polymerase and Nucleotides. 

1.Primers are short pieces of DNA which are designed to copy very specific DNA sequence.2 primers are used in PCR, one attaches to the top strand at one end of the desired segment and the other attaches to the bottom strand at the other end. 

2.DNA polymerase molecules read the DNA code and then attach matching nucleotides to create the DNA copies.

3.Nucleotides are genetic building blocks which are used to create the DNA copies. 

Gel Electrophoresis 

Allows to determine the lengths of DNA strands. Gel is used as a filter that sorts DNA strands while electrophoresis is the process of pushing DNA stands through the gel filter by using electrical current. The DNA strands in the sample will then sort themselves. Afterwards, staining the sorted groups of DNA makes it visible to naked eye. 

- The lysis solution contains detergent and enzyme proteinase K. The detergent disrupts the cell membrane and nuclear envelope, causing the cells to burst open and release their DNA. The DNA that is wrapped very tightly around histones(proteins) are freed as the proteinase K cuts apart the histones to free the DNA.
- After the step of adding salt solution to allow proteins and other cellular debris to clump together, Isopropyl alcohol is added to the new tube and inverted for several times. DNA is not soluble and does not stay dissolved in Isopropyl alcohol. Therefore, it comes out of the solution and we can now see clumped DNA with our naked eye.

PCR:
- PCR is used every day to diagnose diseases, identify bacteria and viruses, match criminals to crime scenes, and in many other ways. 
- When Primer 1 and Primer 2 are added to the PCR tube, they will attach to sites on the DNA strands that are at either end of the segment we want to copy. 
- Nucleotides are the ‘A’s, ‘C’s, ‘G’s and ‘T’s that make up the DNA code. These genetic building blocks will be used to create billions of DNA copies. 

Gel Electrophoresis:

- Used to sort and determine the different sizes of DNA strands that cannot be seen or measured using a normal ruler. 
- The gel acts as a filter to sort the DNA strands. 
- Electrophoresis is when electric current is used to move the DNA strands along the gel. The shorter strands move faster than the longer strands of DNA. 

PCR can generate numerous identical copies of DNA sequence. PCR needs DNA that has been extracted from cells as the main purpose is to generate more DNA copies. DNA double helix separates at high temperature which creates 2 single stranded DNA molecules which will attempt to pair up but the primers added will attach to sites on the ends of the DNA strands that makes the copy. Nucleotides are the A’s, C’s, G’s and T’s that make up the DNA code. DNA polymerase molecules read the DNA code and then match identical nucleotides to create the DNA copy. 

Gel electrophoresis is used to sort and measure DNA strands that are not visible. It is usually used when DNA strands are needed to be sorted according to length. Electric current is added to make the DNA move from one end of the gel to the other. DNA strands of the same length would move at the same speed together. Staining allows the DNA to be visible. To carry this out, first the gel has to be made, the gel apparatus has to be set up, the DNA has to be loaded onto the gel, and the electrical current has to run through the gel and lastly, staining the gel and analyzing the results.