A plasmid is a ring-shaped piece of DNA that can transfer genes between bacteria. It contains non-essential genes for traits like antibiotic resistance. Researchers can create recombinant DNA by splicing genes into plasmids, then inserting these plasmids into cells to produce large quantities of proteins for research. For example, scientists generated heart muscle cells by adding seven genes to plasmids and introducing them into stem cells.

1. Johan Harris, Block 4

2.  A plasmid is a ring-shaped piece of DNA
found in bacteria, fungi, and even some
plants.
 Plasmids float freely in the cell and are
independent from the chromosomal DNA.

3.  A plasmid does not contain genetic information
that is essential for the organism’s survival.
 Genes in a plasmid are split up into two
categories-
1. Backbone Genes – contain info for transfer and
upkeep of the plasmid
2. Accessory Genes – contain info for beneficial effects
such as antibiotic resistance; even though these
genes are not necessary, they may be advantageous
in the fight for food and space

4.  Plasmids can be transferred from cell to cell.
 This ability is what lets bacteria adapt to new
environments extremely quickly.
 The process by which a plasmid is shared is
called conjugation.
 The DNA is split into two strands, one stays in
the donor cell and the other is given to a
recipient cell through what is called the mating
bridge, or pilus, connecting the two cells.
 The strands are then used as a template to copy
the DNA and form two strands once again.
 Conjugation In-Depth Animation

5.  In 1959, Japanese scientists were confused as
to why the antibiotic used against dysentery
was not working on select patients.
 After some testing, they found that the strain
of the bacteria infecting their patients had a
gene for resistance on the plasmid against
the antibiotic used.
 This helped form the conclusion that genes of
resistance are always found on the plasmid.

6.  Although plasmids can carry genes that make
antibiotics ineffective, we can use them for
research in a positive way.
 This is when we use what is called
recombinant DNA.

7.  Recombinant DNA is a
plasmid that has had
foreign genes added to it.
 Recombinant DNA can be
used to create massive
amounts of proteins for
research, and has also been
used to add genes to
organisms or cells.

8.  To create recombinant
DNA you must use
restriction enzymes to cut
the plasmid and the DNA
containing the desired
gene.
 “Sticky Ends” form where
the plasmid was cut with
the restriction enzymes
which allow you to splice
in the desired gene.
 Then you can insert the
plasmid into a cell to take
effect.
bio.miami.edu

9.  Proteins are often being studied by
researchers.
 However, before genetic engineering, they
were produced in insufficient quantities and
researchers had to dig through tons of
biomass to get a usable quantity.
 Even with proteins in such small amounts, the
purity of the proteins was still very poor.

10.  To get mass quantities of a protein, a scientist
can do the following-
1. Get the gene for a protein from an animal that
produces it naturally.
2. Use restriction enzymes to cut the plasmid and
splice the gene into place.
3. Insert the plasmid into an E. Coli bacteria and let
it multiply.

11.  Cardiomyocytes – heart
muscle cells that allow
your heart to beat.
 Researchers at Johns
Hopkins Medical
Institutions have created
these cells with plasmids.
 Cardiomyocytes can be
used in transplants and for
testing heart drugs, which
is much needed in today’s popsci.com
world.

12.  The Researchers from
Johns Hopkins took
blood, stem cells, and
plasmids.
 Then, seven genes were
added to the plasmids.
 The plasmids were placed
into the stem and blood
cells, which were allowed
to grow and multiply in a
broth to simulate
embryonic conditions.

13.  Boyle, Rebecca. "Popular Science | New Technology, Science
News, The Future Now." Popular Science | New Technology, Science
News, The Future Now. Popular Science, 8 Apr. 2011. Web. 10 May
2012. <http://www.popsci.com/technology/article/2011-04/new-
cell-building-method-turns-blood-cells-directly-beating-heart-
cells-using-rings-dna>.
 "Genetic Engineering." Science Clarified. Advameg, 2012. Web. 22
May 2012.
<http://www.scienceclarified.com/scitech/Genetics/Genetic-
Engineering.html>.
 "Plasmid." BookRags. BookRags, 2012. Web. 9 May 2012.
<http://www.bookrags.com/research/plasmid-gen-03/>.
 "Plasmids - The Virtual Genome Project." Plasmids -The Virtual
Genome Project. University of Idaho. Web. 23 May 2012.
<http://people.ibest.uidaho.edu/~etop/vgp/plasmids.html>.