Video Transcript
Which of the following best
describes the nucleoplasm? (A) The double membrane that
surrounds the nucleus to separate its contents from the cell cytoplasm. (B) The viscous substance found
within the nucleus that maintains the organelle’s cuboidal shape. (C) A gelatinous liquid found
within the nucleus that contains chromatin. (D) An aqueous solution that is the
site of all the chemical reactions that occur within a cell. (E) The fatty layer that encloses
the nucleolus to separate it from the nucleus.
One of the defining characteristics
of eukaryotic cells is the presence of the nucleus to contain DNA. Let’s take a closer look at the
nucleus and describe some of its parts so we can answer our question.
The nucleus is surrounded by an
inner and outer membrane that together make up the nuclear envelope. The nuclear envelope separates the
contents of the nucleus from the rest of the cell. This protects DNA from any
reactions that are occurring in the cytoplasm.
The outer membrane is continuous
with the endoplasmic reticulum, which you can see here. Only a portion of it is shown for
simplicity, but the endoplasmic reticulum surrounds the whole nucleus.
Surrounding the nuclear membrane
are numerous openings, called nuclear pores. These allow small substances, like
mRNA, to exit the nucleus while keeping larger substances, like DNA, inside the
nucleus.
Inside the nucleus is the DNA and
its chromosomes that are compacted in a state called chromatin. Chromatin is a mixture of DNA and
histone proteins.
The nucleolus is a region of the
nucleus where ribosome subunits are produced. Here there’s lots of proteins, RNA,
and DNA that are responsible for assembling ribosomes. Because of the high amount of
material in the nucleolus, it’s usually easily seen with a microscope.
And finally, the gel-like fluid
that contains the chromatin and all the nucleotides and enzymes needed for DNA
transcription is called the nucleoplasm.
Going back to our question, the
option that best describes the nucleoplasm is given by answer choice (C): a
gelatinous liquid found within the nucleus that contains chromatin.
