Video Transcript
Where are the centromeres located within the eukaryotic cell? (A) Inside the secretory vesicles of the Golgi apparatus. (B) On the outer membrane of the mitochondria. (C) On the chromosomes inside the nucleus. (D) On the large subunit of the ribosome.
One of the defining features of eukaryotic cells is the presence of membrane-bound
organelles. Let’s look at a few examples. Mitochondria are involved in producing energy for the cell. Ribosomes are responsible for synthesizing proteins. They can be found in the cytoplasm of the cell or on the endoplasmic reticulum and
can each synthesize different types of proteins. The Golgi apparatus helps to modify and sort proteins for different locations, for
instance, those that are destined for secretion or to be integrated into the cell
membrane. And the nucleus is the organelle which contains DNA.
DNA is organized into structures called chromosomes. In humans, we have 46 chromosomes in most cells. In this diagram, the chromosomes are long and stringlike and hard to see because
they’re all mixed up with one another. If we pretend that this cell only has two smaller chromosomes, we can see them more
easily. When this cell is preparing for cell division, this DNA needs to be copied. So, in the diagram, we now see two duplicated chromosomes.
If we zoom in on one of these duplicated chromosomes, you’ll notice that each copy of
the chromosome, which are called sister chromatids, are joined at a specific
region. This region is called the centromere and is what keeps the two sister chromatids
attached. It’s also where the spindle fibers attach when these sister chromatids are separated
during cell division.
Therefore, going back to our question, the option that correctly identifies the
location of the centromere is given by answer choice (C), on the chromosomes inside
the nucleus.
