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Thousands of spots are arrayed in orderly rows and columns on a solid surface (usually glass). The precise location and sequence of each spot is recorded in a computer database. Microarrays can be the size of a microscope slide, or even smaller.

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What?
A useful vector for the genetic variation of plants. It is a change in DNA that helps spread good resistant bacteria instead of tumorous bacteria that the plasmid usually carries.
It is a small, circular piece of autonomously replicating DNA. They express antibiotic resistance genes and express proteins of interest.
How?
They artificially introduce the bacterial DNA to the plant, at which point it will encode the plant to create enzymes that the bacteria needs to grow, making the plant a good host.
Why?
By altering the bacteria’s DNA to not transfer disease and instead pass beneficial DNA to plants, they protect and strengthen the plant from various diseases and promote plant cells growing in tissue culture.

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-What?
>DNA probes are stretches of single-stranded DNA used to detect the presence of complementary nucleic acid sequences (target sequences) by hybridization. DNA probes are usually labeled, for example with radioisotopes, epitopes, biotin, fluorophores to enable their detection.
-How?
>Hybridization of DNA is accomplished by heating strands of DNA from two different sources to 86 degrees Celcius. This breaks the hydrogen bonds between all complementary base pairs. The result of this is may segments of single-stranded DNA. The single-stranded DNA from the two sources is mixed together and allowed to slowly cool. Similar strands of DNA from both sources will begin to chemically join together or re-anneal at complementary base pairs by reforming hydrogen bonds. The double-stranded segments of hybrid DNA are then reheated and the temperature is noted. This temperature represents the number of hydrogen bonds formed, and therefore how closely related the two sources are. The two sources can be from two different organisms or from two different types of cells within the same organism.
-Why?
>It can be used to see the genetic distance between different organisms (how closely related organisms are). It can also be used to see where different genes are expressed within the organism. The technique is also being used to study prenatal development; it tells you in which cells of an embryo that genes are turned on and off.

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What?
A technique to make many copies of a specific DNA region in vitro (in a test tube rather than an organism)

How?

1. Denaturation: The sample is heated so the DNA denatures, or separates into two pieces of single-stranded DNA

2. Annealing: The reaction temperature is decreased and the PCR primers bind to their complementary sequences on the single-stranded template DNA

3. Extension: The reaction temperatures are raised and the Taq polymerase synthesizes two new strands of DNA, using the original strands as the template.

Why?
PCR produces enough DNA to be analyzed using other techniques
-Gel electrophoresis
-Sequencing
-DNA cloning

PCR has practical applications
-Amplify genes associated with genetic disorders from the DNA of patients
-Test for bacterium or DNA virus in a patient's body

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--What?

This type of DNA cloning procedure involves a gene or other DNA fragment of interest is inserted into a circular piece of DNA called a plasmid. This combination creates a recombinant DNA in the bacteria, which has the means to produce proteins needed in the organism’s body. An example of this is the human insulin gene being expressed in E. coli bacteria to make insulin used by diabetics.

In a typical DNA cloning procedure, the gene or other DNA fragment of interest (perhaps a gene for a medically important human protein) is first inserted into a circular piece of DNA called a plasmid. The insertion is done using enzymes that “cut and paste” DNA, and it produces a molecule of recombinant DNA, or DNA assembled out of fragments from multiple sources. The plasmid is then introduced to the bacteria. The bacteria then grows up and reproduces, passing the recombinant DNA to their offspring. The bacteria are used as “factories” to make the protein.

Ex: For instance, the human insulin gene is expressed in E. coli bacteria to make insulin used by diabetics.

-How?

1.Cut open the plasmid and "paste" in the gene. This process relies on restriction enzymes (which cut DNA) and DNA ligase (which joins DNA).

-The restriction enzyme recognizes a specific target sequence and cuts DNA into two pieces at or near that site, and the DNA ligase seals gaps in the DNA backbone.

2. Introduce or transform plasmid to the bacteria

-Plasmids and other DNA can be introduced into bacteria in transformation. During transformation, specially prepared bacterial cells are given a shock (such as high temperature) that encourages them to take up foreign DNA.

-A plasmid typically contains an antibiotic resistance gene, which allows bacteria to survive in the presence of a specific antibiotic. Thus, bacteria that took up the plasmid can be selected on nutrient plates containing the antibiotic. Bacteria without a plasmid will die, while bacteria carrying a plasmid can live and reproduce. Each surviving bacterium will give rise to a small, dot-like group, or colony, of identical bacteria that all carry the same plasmid.

3. The bacteria grows, reproduces, and passes the recombinant DNA to their offspring. Then the bacteria are used as “factories” to make protein.

-For example, if the plasmid contained the human insulin gene, the bacteria would start transcribing the gene and translating the mRNA to produce many molecules of human insulin protein.

-Because there are other macromolecules and proteins floating around in the bacteria, the specific protein (in this case, insulin) must be purified in order to be expelled from the cell and used in other parts organism’s body.

4. Research and Application

-Why?
In some cases, we need lots of DNA copies to conduct experiments or build new plasmids. In other cases, the piece of DNA encodes a useful protein, and the bacteria are used as “factories” to make the protein

EXAMPLES
-Gene analysis. In basic research labs, biologists often use DNA cloning to build artificial, recombinant versions of genes that help them understand how normal genes in an organism function.
- Gene therapy. In some genetic disorders, patients lack the functional form of a particular gene. Gene therapy attempts to provide a normal copy of the gene to the cells of a patient’s body. For example, DNA cloning was used to build plasmids containing a normal version of the gene that's nonfunctional in cystic fibrosis. When the plasmids were delivered to the lungs of cystic fibrosis patients, lung function deteriorated less quickly
-Biopharmaceuticals. DNA cloning can be used to make human proteins with biomedical applications, such as the insulin mentioned above. Other examples of recombinant proteins include human growth hormone, which is given to patients who are unable to synthesize the hormone, and tissue plasminogen activator (tPA), which is used to treat strokes and prevent blood clots. Recombinant proteins like these are often made in bacteria.

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What? - A form of cloning where one nucleus is replaced by a nucleus from a different cell. There are two types of cloning by nuclear transfer: one for reproduction (reproduction) and one for somatic cells (therapeutic). Reproductive cloning involves creating an animal that is genetically identical to a donor animal through somatic cell nuclear transfer. In reproductive cloning, the newly created embryo is placed back into the uterine environment where it can implant and develop. Dolly the sheep is perhaps the most well-known example. In therapeutic cloning, an embryo is created in a similar way, but the resulting "cloned" cells remain in a dish in the lab; they are not implanted into a female's uterus.

How? -Nuclear transfer starts by removing the nucleus from one cell, such as a skin cell, and injecting the skin cell nucleus into another cell, such as a muscle cell, to clone the muscle cell into the skin cell. A new clone—a genetic copy of the donor—forms when the egg starts to divide.

Why?- This technique inspired the development of SCNT (Somatic Cell Nuclear Transfer), which has become an important technique in stem cell research and in understanding the cellular mechanisms controlling embryonic development and nuclear reprogramming. Somatic cell nuclear transfer research is an important subset of stem cell research and could allow researchers to develop stem cell therapies that are specifically tailored to an individual’s medical condition and that do not trigger an immune rejection response.

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What: A DNA micorarray allows scientists to perform an experiment on thousands of genes at the same time. Each spot on a microarray contains multiple identical strands of DNA. The DNA sequence on each spot is unique. Each spot represents one gene.
How: Thousands of spots are arrayed in orderly rows and columns on a solid surface (usually glass). The precise location and sequence of each spot is recorded in a computer database. Microarrays can be the size of a microscope slide, or even smaller.
Why: Used to see what genes are turned on or off and to what degree.

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WHAT? is used to separate mixtures of DNA, RNA, or proteins according to molecular size.
HOW? it involves running a current through a gel containing the molecules of interest. Based on their size and charge, the molecules will travel through the gel in different locations and different speeds, allowing them to be separated from one another. When a gel is stained with a DNA-binding dye, the DNA fragments can be seen as bands, each representing a group of same-sized DNA fragments.
WHY?  Scientists and doctors can use gel electrophoresis to compare DNA samples because enzymes only cut the DNA at certain sequences. When these sequences go through electrophoresis, they will produce DNA molecules of corresponding sizes. This process then enables us to match, compare, and identify DNA.