Video Transcript
Genes can be manufactured using a
gene machine. This uses a mixture of
bioinformatics and laboratory techniques, an outline of which is in the diagram
provided. Put these statements in the correct
order.
This question asks us about
synthesizing genes using the amino acid sequence in a protein. We can do this using a special
device called a gene machine. Let’s go over the different steps
of this process and put them in the correct order so we can answer this
question.
The first step in using a gene
machine is to select the protein that we want to synthesize a gene for. Let’s choose insulin as an
example. Once we have chosen a protein, we
can input the amino acid sequence into the gene machine. We’re only showing a segment of the
insulin protein sequence here for simplicity. This represents the first step of
the process, which is indicated as statement 3 on the left. So let’s write that down.
Next, the gene machine uses this
amino acid sequence to determine the corresponding mRNA sequence as codons. Next, the corresponding DNA
sequence for both strands is worked out by the gene machine. These steps are represented in
statement 1 in the diagram, so let’s indicate that.
Now that we have the gene’s DNA
sequence, the gene machine will synthesize the gene. To do this, it first must
synthesize short fragments of DNA called oligonucleotides. Two of them will be shown in this
example. These short fragments correspond to
either strand of the insulin DNA molecule, and they overlap each other. Here, they’re shown as six
nucleotides long, but in real life, oligonucleotides are a bit longer at around 13
to 25 nucleotides. These steps are indicated in
statement 2 on the left.
These oligonucleotides are then
joined together and extended to form the rest of the DNA sequence on one strand
using a special technique called polymerase chain reaction, or PCR. You can see the sequence on the
bottom strand being extended by PCR here. These steps are indicated in
statement 5 on the left.
Now, this single strand of DNA can
be made double-stranded as the other oligonucleotide is extended. You can see this on the top
strand. This is now a double-stranded DNA
molecule with the sequence of the insulin gene, which corresponds to the protein
sequence initially entered. This last step is indicated as
statement 4 on the left.
And now we have the correct order
of these statements for manufacturing a gene using a gene machine: 3, 1, 2, 5,
4.
