Video Transcript
Chromosomes are found in the
nucleus of our cells. Which of the following best
describes the structure of a chromosome? (A) A chromosome is a long molecule
of DNA that is coiled around proteins. (B) A chromosome is a short,
flattened section of DNA that contains enzymes. (C) A chromosome is a section of
DNA that contains the information needed to produce a protein. (D) A chromosome is the part of the
cell where genetic material is contained.
We’re all different from each
other. Some of us have blue eyes, and
others have green eyes. Our DNA gives the instructions for
these different characteristics. DNA is contained in the nucleus of
our cells, and there’s a lot of it. In fact, if you were to take out
all the DNA from a single human cell, it would be about two meters in length. This isn’t one long piece of DNA;
it’s actually broken up into 46 pieces that we call chromosomes. Let’s look at one of these
chromosomes in more detail.
Each chromosome is a single long
molecule of DNA that is coiled around special proteins called histones. These proteins help compact the DNA
so all of it can fit inside the nucleus of a cell. Different segments of DNA, called
genes, contain the instructions for making proteins that give us our different
characteristics, like the color of our eyes.
Now let’s go through the answer
choices to see which one best describes a chromosome.
Answer choice (A) seems to be
correct because a chromosome is a long molecule of DNA that’s coiled around histone
proteins. But let’s look at the other choices
before making our final decision.
Answer choice (B) describes a
chromosome as a short, flattened section of DNA that contains enzymes. This is incorrect.
Answer choice (C) describes a
chromosome as a section of DNA that contains the information needed to produce a
protein. This is actually describing what a
gene is, so this is incorrect.
Answer choice (D) describes a
chromosome as a part of the cell where genetic material is contained. This is a good description for the
nucleus, not a chromosome, so this answer is incorrect.
Therefore, the answer choice that
best describes a chromosome is given by (A). A chromosome is a long molecule of
DNA that is coiled around proteins.
