Video Transcript
What is a genome? (A) The lifestyle factors that
influence an organism. (B) All the noncoding DNA in an
organism. (C) The physical appearance of an
organism. (D) All the coding DNA in an
organism. (E) All the DNA within an
organism.
Our genetic information is stored
in the nucleus of our cells as DNA. We have a lot of DNA. And if you were to line up all the
DNA in a single cell, there would be about two meters of it. This is not one single piece of
DNA. In fact, it’s organized into 46
structures called chromosomes. Let’s take a closer look at one of
these chromosomes.
If we unravel a single chromosome,
we can see that it’s made up of DNA that’s tightly wound up around special proteins
called histones. Specific sequences of DNA that code
for a functional unit, such as a protein, are called genes. These genes can give our body all
of its characteristics, like the color of our eyes or hair, for example.
As you can imagine, there’s a lot
of DNA in a single cell. We can broadly categorize this DNA
as coding or noncoding DNA. Coding DNA represents the genes
that code for different proteins, like insulin or hemoglobin, for example. This represents only about one
percent of all of our DNA. Noncoding DNA represents the DNA
that doesn’t code for proteins. These sequences can be involved in
regulating gene expression, for instance. This makes up about 99 percent of
our DNA. Together, all this coding and
noncoding DNA make up our complete set of DNA that we call the genome.
Therefore, the response that best
describes what a genome is is given by answer choice (E): all the DNA within an
organism.
