DNA Technology
Biotechnology
Biotechnology can be defined as the use of technology to control biological
processes as a means of meeting societal needs
At its most basic level, biotechnology includes animal and plant breeding
Biotechnology is a broad category that currently encompasses:
The production of transgenic organisms
Techniques to clone animals
The reprogramming of cells to become different types of cells
The use of biotechnology in forensics
A transgenic organism is an organism whose genome carries one or more genes
from another species
Many biotechnology products are produced within transgenic organisms
Genetic Engineering
The production of transgenic organisms makes use of recombinant DNA
technology
This makes use of enzymes normally produced in bacteria
Restriction enzymes
DNA ligase
Scientists have
genetically engineered bacteria to mass-produce a variety of useful
chemicals, from cancer drugs to pesticides, and
transferred genes from bacteria to plants and from one animal species to
another
Recombinant DNA Techniques
Bacteria are the workhorses of modern biotechnology
To manipulate genes in the laboratory, biologists often use bacterial plasmids
- small, circular DNA molecules that duplicate separately from the larger
bacterial chromosome
DNA from any organism (including humans) can be inserted into plasmid
DNA
Plasmid DNA is isolated from bacteria
The transgenic bacteria can then produce the gene products desired
Restriction enzymes act as molecular scissors, recognizing specific DNA
sequences and cutting them
Cutting both the target DNA and the plasmid DNA with the same
restriction enzyme gives complementary “sticky ends”, allowing splicing
of the target DNA into the plasmid
This produces recombinant DNA
Gel Electrophoresis
Cutting DNA gives a variety of DNA fragments
We often need to separate those fragments using gel electrophoresis
This method separates the DNA fragments based on length
The same recombinant DNA techniques are used to make other transgenic
organisms
Like golden rice or cassava enriched for beta carotene to help prevent
Vitamin A deficiency and its resulting blindness
or the Innate potato that resists bruising and produces less of a cancercausing chemical when fried
or the Arctic apple that resists turning brown when sliced or bruised
3/20/15 The Food and Drug Administration said that genetically
engineered non browning apples and bruise-resistant potatoes
were as safe and nutritious as their conventional counterparts
or transgenic goats producing important proteins in their milk
or even cows producing hypoallergenic milk
2-3% of babies are allergic to cow milk and experience diarrhea and
vomiting
Human Gene Therapy
Human gene therapy is intended to treat disease by introducing genes into an
afflicted person
In cases where a single defective gene causes a disorder, the mutant version of
a gene may be replaced or supplemented with the normal allele
This could potentially correct a genetic disorder, perhaps permanently
In other cases, genes are inserted and expressed only long enough to treat a
medical problem
Despite all of the promise associated with this technology, there have been few
successes
2000-2011 - gene therapy cured 22 children with severe combined
immunodeficiency (SCID)
These patients had no immune system, requiring them to remain isolated
within protective “bubbles”
However, there were some problems as well
DNA Profiling and Forensic Science
DNA profiling
is the analysis of DNA samples to determine whether they come from the same
individual and
has rapidly transformed the field of forensics
To produce a DNA profile, scientists compare sequences in the genome that
vary from person to person
DNA Profiling Techniques - PCR
The polymerase chain reaction (PCR)
is a technique by which a specific target segment of DNA can be amplified
quickly and precisely, and
permits scientists to obtain enough DNA from even minute amounts of
blood or other tissue to allow a DNA profile to be constructed
Short Tandem Repeat (STR) Analysis
How do you prove that two samples of DNA come from the same person?
Repetitive DNA makes up much of the DNA that lies between genes in humans
Short tandem repeats (STRs) are short sequences of DNA tenderly repeated
many times in the genome
DNA profiling can also be used to confirm paternity
Genomics
Genomics is the study of complete sets of genes (genomes) of organisms
The Human Genome Project
Begun in 1990, the Human Genome Project was a massive scientific
endeavor to
determine the nucleotide sequence of all the DNA in the human genome
and
identify the location and sequence of every gene
More than 99% of the genome had been determined to 99.999% accuracy
About 3 billion nucleotide pairs were identified
About 21,000 genes were found
About 98% of the human DNA was identified as noncoding
Some noncoding DNA is made up of gene control sequences (promoters,
enhancers, and microRNAs)
Some noncoding regions include introns and repetitive DNA
Some noncoding DNA is important to our health, with certain regions
known to carry disease-causing mutations
The function of most noncoding DNA is unknown
The DNA sequences of ancient species have also been determined, including our
relatives
In 2013, scientists sequenced the entire genome of a 130,000-year-old female
Neanderthal (Homo neanderthalensis)
Scientists used DNA extracted from a toe bone found in a Siberian cave to
identify a new species (Homo denisovans) related to modern humans