Video Transcript
Organisms belonging to the kingdom
Protista are eukaryotic. Which of the following best
explains what this means? (A) The cells of the organism
contain the majority of their genetic material in a single-looped chromosome. (B) The cells of the organism
contain the majority of their genetic material in multiple plasmids. (C) The cells of the organism
contain the majority of their genetic material in a membrane-bound nucleus. Or (D) the cells of the organism do
not contain any genetic material.
This question asks us to find the
answer choice that gives the best definition for eukaryotic organisms. So let’s dive into some
definitions.
A cell is the basic unit of life
and contains at least a membrane which encloses cytoplasm, many biomolecules, and
genetic material in the form of nucleic acids: DNA and RNA. With this information in mind, we
can eliminate option (D), which suggests that the cells of a eukaryotic organism do
not contain any genetic material, because all cells contain genetic material,
including eukaryotic cells.
The way that cells store their
genetic material is one of the most notable differences between eukaryotes and
prokaryotes, like bacteria. The genetic material of prokaryotic
cells is found in the cytosol in the form of circular chromosomes and smaller loops
of extrachromosomal DNA called plasmids. Eukaryotic DNA is most often stored
in linear chromosomes, not looped chromosomes or plasmids. We can therefore eliminate option
(B), proposing that the cells of the organism contain the majority of their genetic
material in multiple plasmids.
Option (A) would therefore also be
incorrect, as it states that eukaryotic cells contain the majority of their genetic
material in a single-looped chromosome, which is not the case.
Unlike prokaryotic organisms,
eukaryotic cells usually have a membrane-bound nucleus and other membrane-bound
organelles. The cell’s nucleus contains almost
the entire genome, meaning that it contains the majority of the genetic
material. This means that we’ve found the
best definition of a eukaryotic cell and therefore the correct answer to this
question. The correct answer is (C). The cells of the organism contain
the majority of their genetic material in a membrane-bound nucleus.
