Biotechnology

Today, scientists have a much faster and more effective way to manipulate variation and selection… manipulation of DNA!

Biotechnology includes:

- Transgenic Organisms

- Clones

- Gene Therapy

- Gel Electrophoresis

- PCR

-Genetic Engineering

The Human Genome

•A genome is all the DNA in an organism.

•After a genome is completed scientists have a “map” showing where particular genes are located on a chromosome

•The particular order of As, Ts, Cs, and Gs in a genome is extremely important. The order will tell whether an organism is human or another species such as yeast, rice, or fruit fly, all of which have their own genomes.

•The human genome, has 3 billion pairs of bases. If you started reading the sequence out loud right now, it would take almost 10 years to read the entire thing!!!

The Human Genome Project

•Organized in 1990 by US scientists; international effort to map and sequence the genes on the 46 human chromosomes

•Completed in 2003, with final papers published in 2006

Project goals were to :

* identify all the approximately 20,000-25,000 genes in human DNA,

* determine the sequences of the 3 billion chemical base pairs that make up human DNA,

* store this information in databases,

* improve tools for data analysis,

* transfer related technologies to the private sector, and

* address the ethical, legal, and social issues (ELSI) that may arise from the project.

How is this important to us?

–Diagnosis of genetic disorders

–Gene therapies

–Genetic Engineering

Genetic Engineering

Genetic engineering is manipulating genes for practical purposes

•May involve building recombinant DNA-Recombinant DNA is DNA made from two or more different organisms

•This is how we are able to put jellyfish “glowing” genes in the bacteria

•Can result in a transgenic organism with recombinant DNA

Transgenic Organisms

  • Transgenic: any organism that has a segment of DNA that was not originally their own.
  • Scientists can take DNA from an organism, cut out a particular gene they want, make millions of copies of it, and insert those copies into the cells of a different organism of choice.
  • The organism will then show the characteristics of that new gene.

Genetic material from jellyfish were injected into the womb of a sow which gave birth to the three pigs 114 days later.

The mouth, trotters and tongue of the pigs are green under ultraviolet light.

Applications of Transgenic Organisms

•Transgenic bacteria:

–Important for health, industry, and the environment (used in medicines, help clean up oil spills, etc.)

•Transgenic plants:

–food supply (increased nutrition, resistance to certain plant diseases)

•Transgenic animals:

–Used to study genes and improve the food supply (altered to grow faster, stronger, and produce higher yields)

Recombinant DNA

•Scientists often need to make a lot of recombinant DNA tostudy it.

•Scientists use host cells, such as bacteria, to copy therecombinant DNA.

•A carrier, known as a vector, is used to carry the recombinant DNA into the host cell.

•One commonly used vector is a small, circular, double-stranded DNA molecule called a plasmid.

•A plasmid only contains a few genes

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Cloning

•Cloning is the process of making a genetically identical organism

•(Dolly was the first cloned organism from an adult cell)

•Many genetically identical cells can be produced from a single cell

•Cloning IS NOT “Xeroxing” a person

•Cloning re-creates the genes of the ancestor, not what he has learned or experienced.

•Technically, it re-creates the genotype, not the phenotype

Gene Therapy

•Gene Therapy is the process of replacing an absent or faulty (bad) gene with a normal, working gene.

•Still relatively experimental

Polymerase Chain Reaction

Sometimes scientists need to get many copies of a specific DNA sequence (gene) very quickly so they perform a Polymerase Chain Reaction.

PCR works like this:

1. Scientists place a fragment of DNA in a machine,

2. They heat-shock it to cause the hydrogen bonds to come lose

3. They add nucleotides into the mix and an enzyme that will bond the complimentary bases to the loose sides of the DNA fragment,

4. Then cold-shock it to cause the hydrogen bonds to reform.

Basically, PCR is a really fast way of making a cell undergo DNA replication millions of times outside of the cell in just a few hours.

Applications of PCR

  • Invaluable when only a tiny sample of DNA is available (like trace evidence in a crime scene or the last bit of pulp from a fossil tooth)
  • You could make millions of identical DNA sequences in approximately 2 hours!
  • Scientists discovered a preserved Wooly Mammoth and if they wanted to clone it they would need to perform a PCR to generate larger quantities of the preserved DNA

Gel Electrophoresis

•Gel Electrophoresis is a technique used to separate DNA fragments by fragment length

•The bands that are created are unique to each person (since DNA sequences are unique to each person)

The Process

1. The same sections of DNA from multiple people are cut into smaller pieces using restrictionenzymes.

(Restriction enzymes are the “molecular scissors” that cut DNA into specific pieces)

2. The pieces are then negatively “charged”, meaning that when they come in contact with an electric current, they move towards the positive end (like a magnet).

3. They are then loaded into a gel

4. Electric current is then run through the gel.

  • The negative DNA fragments move through the gel towards the positive end.
  • Since the DNA sections are all different sizes, the bands separate by size.
  • Larger piecesmove slower.

Applications of Gel Electrophoresis

DNA testing for paternity cases:

• Every person’s DNA fragments separate out a little bit differently in an Electrophoresis Gel, because we are all different. So, individuals can be identified by the banding pattern their DNA makes in the gel.

•Children have a combination of both their parents’ DNA, so when trying to determine parents, the children will have a combination of their parent’s bands.

Can you determine the correct suspect?

At a crime scene involving a murder, police recovered skin cells under the victim’s fingernails. The DNA in the skin cells was analyzed- it was not the victim’s, and thus was presumed to be the assailant’s. Three suspects were arrested for matching the description given by several witnesses. Their individual DNA was analyzed, and the results are shown below. Can the correct suspect be determined?

Using a ruler or a straight edge, determine which suspect has each band of DNA is the same location