Video Transcript
The picture provided shows an
electron micrograph of Escherichia coli. What features does this organism
have that mean it is classified into the kingdom Monera? (A) A membrane-bound nucleus that
stores the genetic material. (B) A cell wall surrounding the
cell, not containing cellulose or chitin. (C) Photosynthetic pigments
contained within organelles. (D) Membrane-bound mitochondria,
Golgi apparatus, and endoplasmic reticulum. Or (E) flagella and pili extending
from the cell surface.
The question asks us to identify
the features of Escherichia coli that classify it within kingdom Monera. You’ve likely heard this organism
referred to as E. coli and know that it is a type of bacteria.
Bacteria, like all members of
kingdom Monera, are prokaryotes. Prokaryotic cells do not have a
membrane-bound nucleus or organelles. The DNA of bacteria such as E.
coli floats freely in the cytoplasm and is typically found on a single
chromosome, as well as on small, circular structures called plasmids. In contrast, eukaryotes have a
membrane-bound nucleus and a variety of organelles, some of which are shown in the
diagram.
Returning to our question, we can
see that answer choice (A) refers to a membrane-bound nucleus, so we can eliminate
it. Answers (C) and (D) refer to
organelles, so we can rule both of them out as well. Answer choice (E) mentions flagella
and pili, which are structures used for cell motility by many organisms in kingdom
Monera. However, flagella can be found on
organisms of all kingdoms. For example, male sex cells, called
sperm, are found in animals, plants, and algae. The sperm cells use their flagella
to swim to their destination, female sex cells. So flagella are not unique to
kingdom Monera, and we can eliminate answer choice (E).
Members of kingdom Monera have cell
walls for structure and support, as do plants and fungi. But prokaryotic cell walls do not
contain the cellulose found in plant cell walls or the chitin found in fungal cell
walls. Bacterial cell walls are typically
made of a substance called peptidoglycan. So we can confidently say that
answer choice (B) is correct.
The feature of Escherichia
coli that places it in kingdom Monera is a cell wall surrounding the cell,
not containing cellulose or chitin.
