It’s Professor Dave, let’s explore biotechnology.
In this biology series we’ve learned a lot about cells, their structure, and the genome within.
Along with a sophisticated understanding of any science comes not just an enhanced worldview,
but also the opportunity to apply this knowledge in order to create technology.
This represents our ability to shape the world as we see fit.
There are certainly profound ethical implications that emerge when we begin to tamper with life.
Some say we shouldn’t play god, whereas others believe we were destined to do just that.
This discussion goes beyond the scope of this course, so let’s instead just go through
a summary of some of the incredible technologies we have been able to develop in the 20th and
21st centuries through an enhanced understanding of biology.
The first key to biotechnology was learning about DNA and what it does.
Once we had this comprehension, we set about trying to sequence the genome of humans and
other organisms.
This is the incredible task of documenting the precise sequence of base pairs in every
single chromosome of a cell.
Given that this includes many billions of base pairs, it seems utterly daunting, but
the sequencing of the human genome was completed in 2003.
Since then, a variety of different sequencing techniques have been developed to make this
process faster and cheaper, and we have been able to sequence the genomes of thousands
of other species.
What can we do with this information?
For starters, we can sequence the genome of cancer cells to find out exactly where the
mutation is, and then develop strategies to combat that particular form of cancer.
We can identify genetic susceptibility to a variety of diseases, and diagnose others,
so that individualized treatment can precede the onset of symptoms.
We can gain valuable insight into bacteria and other pathogens, so we know how to fight them.
Beyond this, our understanding of DNA has allowed us to make copies of any gene we want.
This is called DNA cloning.
To do this, instead of laboriously synthesizing strands of DNA, we put bacteria to work, since
they have all the machinery that nature evolved to copy DNA in the first place.
Let’s say we have a gene of interest that we want to learn more about.
We can take a plasmid, or circular DNA molecule, from a bacterium like E. coli, and insert
our gene into the plasmid.
This is now called recombinant DNA, because it contains DNA from two different sources,
the bacterial genome, and the gene we are studying, which could be from any organism.
Then we put the plasmid back into the bacterium, and as it divides over and over again, it
copies all of the DNA each time, including our gene of interest.
This is highly efficient because the bacteria do all the work, and they do it very fast.
Don’t worry, they don’t mind helping out.
Another method for copying or amplifying DNA sequences is called the polymerase chain reaction,
or PCR.
This is done by taking some double-stranded DNA sequence and heating it up so that it
denatures, meaning that the strands separate.
Then things are cooled to a specific temperature so that DNA primers can anneal, and then a
heat-stable form of DNA polymerase goes ahead and extends the primers from 5-prime to 3-prime
until all the DNA is copied.
We now have two copies of the DNA molecule.
We use this special polymerase because normal polymerase would denature at these hot temperatures
that are needed to get the DNA strands to separate.
This cycle will then repeat over and over, yielding four copies, then eight, and so forth,
growing exponentially until there are billions of copies within a few hours.
This technique is often used to generate a supply of a particular DNA fragment that can
be used in the cloning technique we described earlier, since this is how we can get the
fragment to include a restriction site that matches the one in the plasmid where this
DNA will be inserted, as we need certain enzymes to know how to chop things up and put them
back together the way we want them to.
Once we have all of these genes copied, what do we do with them?
Well, we can do a wide variety of things.
We can harvest all of the copies of our gene and insert them into some other organism,
to provide pest resistance to some plant, or engineer microbes that can clean up ocean waste.
Or, we can harvest the products of all this gene expression, like insulin or human growth
hormone, which we can use to treat various diseases.
Beyond cloning genes, we have also figured out how to clone entire organisms.
This is called organismal cloning.
This was first achieved in the 1950’s with plants, where already differentiated cells
from a carrot were taken from the root, which then were able to dedifferentiate and divide,
leading to the production of a new genetically identical carrot plant.
More studies of this type led to the cloning of other organisms through nuclear transplantation,
including the famous lamb, Dolly, in 1997, and other animals like cats, dogs, and cows
since then.
Cloning technology also led to an interest in stem cells, which are unspecialized cells
that can divide indefinitely and become cells of any type.
This is an area of study with great promise in curing conditions dealing with damaged
tissue, including spinal cord injury.
For this reason, human cloning has been an area of heavy research, so as to produce stem
cells for the treatment of conditions ranging from diabetes to Parkinson’s.
But the morality surrounding the cloning of embryonic stem cells is a gray area, so research
has turned largely to induced pluripotent stem cells, which are differentiated cells
that have been reprogrammed to act like embryonic stem cells, therefore removing any ethical
haziness associated with utilizing actual embryos.
This was first achieved in 2007 with skin cells from a mouse, and since then with human
skin cells.
With all of these technologies and more on the way, human potential seems truly limitless.
We are exploring gene therapy, and other techniques, which hold the promise of bringing total immunity
to all disease.
We are discovering how we might eradicate the aging process, in effect manufacturing
immortality.
Will we figure out how to do this, and should we?
It’s difficult to say, but we must remember that although the future may seem scary, the
present would seem just as terrifying to anyone from the past.
Cars and planes that drive themselves using tiny machines that can think, this is enough
to put someone from the 17th century into a fear-induced coma.
So for the sake of our species, we must boldly go forward into the future, intrepid as we
have always been, drawing ever closer to the ultimate destiny of mankind, whatever that may be.