Use the following mRNA codon key as needed to answer the...

Use the following mRNA codon key as needed to answer the next two questions: GCC Alanine AAU Asparagine CCU Proline GGA Glycine UGG Tryptophan UGA "Stop" (no amino acid) GAA Glutamic acid GAG Glutamic acid CAU Histidine AGG Arginine CCC Proline The following DNA sequence (coding strand) occurs near the middle of the coding region of a gene. DNA: 50 55 60 65 5'- A A T G A A T G G G A G C C T G A A G G A G -3' The corresponding mRNA sequence is shown below. Note that the coding strand of DNA has the same sequence as the mRNA, except that there are U's in the mRNA where there are T's in the DNA. The first triplet of nucleotides AAU (underlined) is in frame for coding, and encodes Asparagine as the codon table above indicates. mRNA 50 55 60 65 5'- A A U G A A U G G G A G C C U G A A G G A G -3' Which of the following DNA mutations is almost certain to result in a shorter than normal protein? A?G at position 61 Insertion of a G after the G at position 54 T?C at position 59 None of these

Transcript

00:01 So you're given a dna sequence, and this is the coding strand occurs near the middle of the coding region of the gene.

00:08 So the first three nucleotide, aat is in fact the first triplet of nucleotide.

00:16 And i also use mrna sequence, write down the mri sequence according to the coding strength.

00:22 So what we know is that the mra sequence is the same as the coding strand of a dna.

00:28 However, since dna has thymine t, but m rna doesn't have t, but it has uresale, whenever there is a t and in a dna, i replace that with the u.

00:42 So as you can see that the mra sequence basically is the same as the dna coding strand, but i replace all the t with you.

00:52 And i also use the number of 50, 55, 60, and 61 to mark the position of nucleotide.

01:00 All right, so now you can see that same as dna, the first three nucleotide, aau, is the first codon.

01:08 So according to the codon, given by the question, aau, is actually represent a specific amino acid asperogen.

01:21 I'm going to use three -letter symbol instead of the full name of amino acid so that it doesn't look too busy.

01:28 So now we know the first amino acid is asperogen and after there you're just going to have to read it in frame, which means every three nucleotide.

01:39 So i'm going to use a bracket to show the frame.

01:43 So the first amino acid or codal is a -a -u.

01:46 The next codon, g -a.

01:49 So this is called the reading frame.

01:52 Every three nucleotide is a codon.

01:54 The next one, u -g -g, the next one g -a -g, the next one g -a -g, the next one c -c, the next one, g -a, the next one g -g -g -a.

02:07 The last nucleotide will not be translated.

02:10 So according to the information we're given by the question, we have the second amino acid.

02:19 G -a is a glutamic acid.

02:23 The next one, new g -g, is going to be a triptophen, trp.

02:26 The next one, g -a -g, again, glutamic acid.

02:33 C -c -u is going to be a proline.

02:38 G -a is going, again, to be a glutamic acid, g -l -u.

02:43 The last one, g -g -g -g -a, is going to be a glycic, g -l -y.

02:49 So, again, this is the original protein amino acid when there's no mutation.

02:56 So the question to ask you, which of the following dna mutation is, certain result in the shorter than normal protein.

03:03 The first one says the a is being replaced by a g at position 61.

03:09 So the 61 is right here.

03:12 So now let's replace that a with g...

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