00:01
So the following segment of dna encoded polypeptide containing six amino acid, the dna triplet that encode the translation star codon and stop codon are included in the sequence.
00:13
So first of all, label which dna strand is template which one is coding.
00:18
So what we know is that a coding strand has the same sequence as mrna.
00:22
And mrna should include star codon and stop codon.
00:28
Star codon is going to be aug or atg.
00:33
In dna and the stop codon you have three it's uaa so in dna is taa uga uga or tga in in dna and uag or tag in dna so these are the sequence in in the dna but if we're looking for rna then it's gonna be you here all right so now if we look look at the sequence from 5 to 3 the top strand that's search for either atg or the one of the stop codon.
01:21
So after i scan the whole top strand, i have found no start and stop codon.
01:31
So now i move on to the bottom string.
01:35
Again, i start to read from the 5 prime end, so this way.
01:38
And then i'm scanning for the start code.
01:42
Now i found one, atg.
01:44
So you can see i read backwards.
01:46
And the next one, the g -c -c, t -c -t -t -g -c, a -a -a -g -g -c.
02:01
And the last one is tag.
02:04
This is our stop.
02:05
Start and stop.
02:12
So from this, we know our bottom strand is the template strand.
02:16
So let me write it down.
02:18
The bottom strand is the coding strand, because it provides the coding information for mrna.
02:24
And the top one that does not have a stop and stop codon.
02:28
This is template.
02:33
So remember, you only find a start codon and stop codon in the coding strand.
02:40
So now that answer the first question.
02:42
We know the bottom is the coding and top is template.
02:45
B, what is the sequence of polarity of mrna encoded by this g? so basically the mrna is going to have the same sequence as your coding strength and the same orientation.
02:58
So to make things easier, i'm going to go with 5 to 3 order.
03:05
So now you can see the bottom strand is the reverse reaction.
03:09
So i'm going to flip the sequence.
03:12
So the first one is going to be a g.
03:15
The second, you have a t here in dna.
03:18
So, m -r -n -a does not have eurasia, or it doesn't have stymine.
03:23
Instead, it has a eurasia, u.
03:25
So whenever you see a t in a dna, a coding strain, you replace that with you.
03:29
So we're just going to do that one by one.
03:33
U.
03:58
U, u, g, c, a, a, g, g, c.
04:11
And u, a, g, g, g, c, u a, g, g, g.
04:24
So now i flip the m rna sequence according to the coding strength.
04:29
So this is m rna.
04:35
The next question.
04:38
The genetic code table is provided.
04:42
So now you can actually go check the table.
04:46
Determine the amino s sequence of the polypeptide.
04:49
Use three letter symbol and identify n and c terminus of the polypeptide...