Video Transcript
True or False: Sequencing the
genome of an organism is sufficient on its own to know the function of any given DNA
segment in this organism.
To answer this question, let’s
first recall ourselves about the genome and the structure of the genome. The genome is the complete set of
genetic material of an organism. In all living organisms, this
genetic material is made of DNA. The DNA of an organism contains
genes, which are segments that produce functional units. These functional units can be
proteins, for example, collagen. Or they can be functional RNA
molecules, for example, transfer RNA, which play important functions in the
cells.
The rest of the DNA situated
between genes doesn’t produce proteins. This DNA is thus called noncoding
DNA. Some examples of noncoding DNA are
the regulatory sequences that control the activity of genes or some noncoding
sequences like the centromeres and telomeres that play important roles in organizing
the structure of DNA in chromosomes.
Now, when scientists want to
investigate the genome of an organism, they can do a sequencing. With this process, they determine
the order of all the nucleotides in the DNA of an organism. This way, scientists know for each
position on the DNA if the nucleotide is a guanine, a cytosine, a thymine, or an
adenine. But knowing the sequence of any
segment of DNA doesn’t necessarily tell scientists what this segment does or if it’s
even coding or noncoding.
In fact, scientists usually go
backwards. From the sequence in amino acids
found in a protein, for example, collagen, they can approximatively deduce the
sequence of DNA of the gene coding for the collagen. Then, they can look for this
sequence in the genome. This way, they determine the
location and function of a gene in the genome.
Nowadays, scientists are helped
with powerful bioinformatic tools that help them make better predictions about the
function of DNA segments. But in general, the answer to this
question is false. Sequencing the genome of an
organism is not sufficient on its own to know the function of any given DNA segment
in this organism.
