00:04
You have three different terms.
00:06
So you want to explain.
00:08
One is rna editing.
00:09
The other is alternative splicing and transplicing.
00:13
So these three terms, you want to match that terms with the statement and describe how it complicates the collinearity.
00:20
The very first concept is what is collinearity? so this actually means that during gene expression, the gene or dna sequences should dictate or decide the protein amino acid sequences.
00:53
So according to the central dogma, when dna is being transcribed into mrna and the mrna is being translated to protein, according to codals, the dna sequence should decide the protein amino acid sequence.
01:08
However, there are a lot of process that happen after transcription that add or subtract or change the nucleotide that actually caused the change in amino acid sequences.
01:19
So this is how we want to explain the three different terms to see how rna modification changed the amino acid sequence.
01:26
Let's first of all look at the first term we called it the rna editing.
01:32
Rna editing according to the definition and also the description, this is a process that add nucleotides through pre -mrna molecule after transcription.
01:42
And of course, this will result in amino acid sequence that does not correspond to the original gene sequences.
01:50
So you start out, obviously, with dna.
01:53
So you have a gene that is double -stranded, and the transcription will obviously happen to produce the pre -mrna.
02:01
The pre -mrna is going to be the single -stranded structure, pre -mrna right here.
02:09
Now, usually pre -mrna will be read as a codon every three nucleotide and pre -mrna will be translated into protein.
02:18
However, during the rna editing, certain complexes added some will add or subtract usually modify the nucleotides and insert it into the pre -mrna.
02:32
So as you can see, in pre -mrna, you have some rare sequence.
02:36
This is being added later.
02:38
So this sequence, rare sequence does not happen in dna gene sequences.
02:42
And this process after the transcription.
02:46
So this means that the dna doesn't dictate amino acid sequence anymore because during the rna editing, additional sequence are being added, which changed according, i guess, the reading frame of mrna, which will give you different amino acid sequences.
03:05
So this is the first concept rna editing.
03:10
You basically add additional nucleotide sequence after transcription, which would obviously cause the difference between the gene sequences and amino acid sequence.
03:21
The second concept we call alternative splicing.
03:25
So first of all, what is splicing? so again, let's start from the dna.
03:34
So regular splicing happens in eukaryotic organisms.
03:38
So say this is a, again, dna.
03:41
Now, first step obviously is again transcription, and you end up having pre -mrna.
03:54
So immediately, pre -mrna will be processed or modified because it will be put on a 5 -prime cap and 3 -prime poly -a -tail to protect it from nuclei.
04:06
And on top of that, there also will be certain sequence that will be cleaved off.
04:11
So you can see some of the rare sequence here we call it intron.
04:21
And the black sequence there is called axon.
04:26
So this pre -mrna will go through the normal splicing.
04:33
So you have three segments of axon they will put together.
04:43
So you have your mrna, which is a mature mrn.
04:46
Now the two introns will be cut away from the final mature mrna.
04:57
So intran will be eventually destroyed.
05:00
So you can see that this is called the regular splicing that the introns will be taken out of pre -mrna, so you have a much shorter, mature, mra.
05:10
So now let's take a look at what is alternative.
05:15
So this means that instead of having only one way to splice the pre -mrna, you can have multiple splicing product...