Video Transcript
Where in a prokaryotic cell is the
chromosomal DNA contained?
You recall that prokaryotes are
single-celled organisms that are often smaller in size compared to eukaryotes and
are distinguished by their lack of a nucleus or membrane-bound organelles. Let’s make this prokaryotic cell a
bit bigger so we can review its anatomy to answer this question.
Many prokaryotes have three layers
that separate the cell’s interior from the cell’s exterior. The capsule is the sticky outermost
layer that some prokaryotes use to stick to surfaces. The cell wall is the middle layer
and helps give the cell its shape and protects the inside of the cell. And finally, there’s the plasma
membrane, which helps to keep the cell’s interior components in place. On the outside of the cell is the
hairlike structure called the pilus, or pili as plural, which can help the
prokaryote with movement. Also helping with movement is a
tail-like structure called the flagellum, or flagella as plural.
If we turn our attention now to the
interior of the cell, we have the cytoplasm, which is the liquid that fills the
inside of the cell. The ribosome is involved in protein
production. And the plasmid is a circular piece
of extrachromosomal DNA that’s separate from the chromosome. Finally, we have the prokaryotic
chromosome, which contains the chromosomal DNA that this question is asking us
about. As mentioned, this is not contained
inside a nucleus. Instead, it’s concentrated in an
area of the cell called the nucleoid. Therefore, in a prokaryotic cell,
the chromosomal DNA is contained in the nucleoid.
