Video Transcript
True or false. The extrachromosomal DNA in
prokaryotes is found in the form of small circular plasmids.
Prokaryotes are single-celled
organisms that are mainly distinguished from eukaryotes by the presence of
membrane-bound organelles. Let’s review the anatomy of a
prokaryote to answer this question.
Many prokaryotes have three
separate layers that separate the inside of the cell from the exterior
environment. The capsule is a sticky outermost
layer that helps prokaryotes adhere to surfaces. The next layer is the cell wall,
which helps protect the cell’s interior and maintains the cell’s shape. Then there’s the plasma membrane,
which contains the interior components of the cell.
On the outside of the cell are
pili, singular pilus, which are short hairlike structures that can help with
movement and are also involved in transferring DNA to other prokaryotes. We can also see a taillike
structure called the flagellum, plural flagella, which can also help the prokaryote
with movement.
In the interior of the cell, we can
see ribosomes, which are involved in protein synthesis. We can also see the prokaryote’s
chromosomal DNA. This DNA often exists as a single
circular chromosome, which is not contained inside a nucleus like eukaryotic
cells. Chromosomal DNA is instead
concentrated in a region of the cell called the nucleoid. This chromosome contains the
majority of the genetic information for the cell.
Additional DNA that isn’t part of
the chromosome, or extrachromosomal DNA, can exist as plasmid DNA. Plasmids are small circular pieces
of DNA that can contain accessory genes that can help the prokaryote adapt to its
environment, such as antibiotic resistance.
Getting back to our question, in
the statement “True or False: The extrachromosomal DNA in prokaryotes is found in
the form of small circular plasmids,” the correct answer is true.
