Video Transcript
The diagram provided shows a
simplified structure of a bacterial cell. Which letter indicates a
plasmid?
Bacteria are a type of prokaryote,
which is one of the major domains of life. Here we can see a diagram of a
bacterial cell. Let’s discuss some of its major
components to answer our question. We’ll start from the outside of the
cell.
Many bacteria have three separate
layers to separate the inside of the cell from its exterior environment. The outermost layer is the
capsule. This is a sticky surface that
allows bacteria to adhere to different materials. 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,
indicated by letter Z, 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 also are involved in transferring DNA to other bacteria. The flagellum, or flagella as
plural, can also help with movement.
In the interior of the cell, we can
see ribosomes, indicated by the letter W, which are involved in protein
synthesis. Then there’s the chromosomal DNA,
indicated by the letter X. This DNA often exists as a single
circular chromosome, which is not contained inside a nucleus like eukaryotic cells
but is rather concentrated in an area of the cell called the nucleoid.
While the chromosomal DNA contains
the majority of the genetic information, additional DNA can be carried on structures
called plasmids, indicated by the letter Y. Plasmids are small circular DNA
molecules that contain genes that can help bacteria adapt to their environment, for
example, by giving them resistance to certain antibiotics.
Going back to our question, the
letter that indicates a plasmid is given by the letter Y.
