00:01
So this question asks you to identify a nucleotide change that doesn't affect amino acid production.
00:08
All right, so let's take a look at all four kind of mutations so we can decide which one is the correct one.
00:14
So first one, what is a silent mutation? a silent mutation is defined as a single nucleotide change does not change the sequence of amino acid.
00:22
So for example, the gene of the original sequence is aaa.
00:26
After transcription, it becomes rna, and rna will actually translate into amino acid.
00:35
So aaa stands for lysine as a particular amino acid.
00:40
Now, in a mutant, due to the single nucleotide change, the a become a t in the third place.
00:47
Now, the aat again become m rna, and the same codon aat will give you the, the same amino acid lysine.
00:59
As you can see, although there is a single nucleotide change from a to t, the mrna is to give you the same codon of amino acid.
01:10
So this is called a silent mutation.
01:13
Second, what is a frame shift? a frame shift mutation means the insertions or deletions of the nucleotides are not multiple of three.
01:22
So they change the reading frame of the entire amino acid sequence.
01:26
So this figure show you an example of frame shift.
01:30
So this is the original amino acid sequence.
01:33
As you can see, each codon on mrna is being read in every three.
01:39
So you can see that it should go with that order.
01:44
But a frame shift mutation, you see there is insertion somewhere in the middle, and it's a single nucleotide mutation insertion.
01:54
So as you can see, the amino acid sequence before the insertion are the same.
02:01
But once you insert the single nucleotide, you push the entire frame forward.
02:07
So it aborted the original reading frame.
02:12
And so you can see all the amino acid sequence or codons that after the insertion is completely different from the original amino acid sequence.
02:22
So this is because the codon is always read in every three nucleotide...