Video Transcript
Which of the following statements
is true? The plasmid is not able to
replicate. Circular DNA exists only in
prokaryotes. (A) Neither statement is true. (B) Both statements are true. (C) The first statement only is
true. (D) The second statement only is
true.
Prokaryotes are single-celled
organisms that are mainly distinguished from eukaryotes by the absence of
membrane-bound organelles. In most prokaryotes, the majority
of prokaryotic DNA can be found as chromosomal DNA. Prokaryotic chromosomal DNA often
exists as a single circular chromosome and is not contained in a nucleus. Rather, it is concentrated in an
area of the cell called the nucleoid.
In contrast, eukaryotes contain
their genetic material within a nucleus, often in the form of multiple linear
chromosomes. However, eukaryotes also have
additional genetic material that can be found in certain organelles, including the
mitochondria and chloroplasts, both of which are involved in producing energy for
the cell. These organelles are believed to
have evolved from prokaryotes and therefore also have circular DNA.
So, we know that circular DNA
exists in eukaryotes as well as prokaryotes, and this statement is not true. Prokaryotes also contain DNA that’s
separate from the chromosomal DNA, but this DNA is not contained within an
organelle. This DNA is called plasmid DNA.
Plasmids are pieces of circular DNA
that contain different genes that can allow the prokaryote to grow in different
environments. Plasmid DNA replicates
independently of chromosomal DNA and can be shared with other prokaryotes in some
situations. So, we now know that this first
statement is also incorrect.
Therefore, the correct option for
this question is given by answer choice (A). Neither statement is true.
