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Current time:0:00Total duration:3:43

DNA libraries & generating cDNA

Video transcript

all right so let's say that you've got this little guy over here and he's got his shoes and it's just happy smile so this guy right here is our protein so let's look at how this protein was created so in order to make protein we have to start out with our base and in this case our base is DNA from DNA we generate messenger RNA and then that message RNA eventually leads to the formation of a protein the protein is this happy guy over here this is pretty straightforward but what if we wanted to go and reverse what if we started out with a protein and we wanted to figure out what its DNA sequence was so if we wanted to go in this direction so let's look at how this is done now scientists thought that it would be nice to basically be able to type in the name of any protein that they're interested in and automatically it would pop up with the DNA sequence of that protein now that is known as a DNA library DNA library and a DNA library would be beneficial for researchers and scientists and clinicians so let's look at how this is done so we'll start out with our protein and our protein is basically a chain of amino acids so amino acids basically are formed from messenger RNA so if we know the amino acid sequence of our protein we can we know what the messenger RNA sequences based on the codon table that we all are too familiar with so if we have the messenger RNA sequence what we do is we add an enzyme known as reverse transcriptase reverse transcriptase and when we add reverse transcriptase basically takes this messenger RNA and makes a complimentary DNA sequence to the messenger RNA and that's known as cDNA and this C stands for complimentary so complementary DNA one thing to keep in mind is single-stranded DNA so normally DNA in our cells is double stranded DNA but complementary DNA is single-stranded so in order to generate double stranded DNA we need to add another enzyme known as DNA polymerase DNA polymerase the DNA polymerase basically generates double-stranded DNA so this cross this is basically step one of the process of creating a DNA library so this is step one now let's look at step two so now that we have our double-stranded DNA what we need to do is sequence it so in order to sequence it we'll start out with our double trainer DNA and we'll basically inject it into some sort of cloning vector such as a plasmid or a virus cloning vector and that cloning vector can then be and then you can take that cloning vector and add it to some bacteria and it'll basically infect the bacteria and the bacteria will basically produce lots and lots of this DNA is double-stranded DNA so that's the that's a process known as amplification amplification and once we have lots of double-stranded DNA we'll go in sequence that double-stranded DNA and basically once we have that sequence will put the sequence into a large database that's readily accessible online and that database will basically populate the DNA library so now anybody that is interested in the DNA sequence of a particular protein can just go into this library and pull up the genetic sequence of the protein of interest