# Protein synthesisWatch

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#1
Base sequence is
GCACCCATATGG
This makes amino acids arginine-glycine-tyrosine-asparagine (in order)

Explain why a mutation that deletes the base found in position X (third A from the left) will result in the production of a polypeptide which is 15, as opposed to 4 amino acids long.

I have no idea! Thank you!!
0
2 years ago
#2
(Original post by algebrax1)
Base sequence is
GCACCCATATGG
This makes amino acids arginine-glycine-tyrosine-asparagine (in order)

Explain why a mutation that deletes the base found in position X (third A from the left) will result in the production of a polypeptide which is 15, as opposed to 4 amino acids long.

I have no idea! Thank you!!
it won't be anything to do with that specific sequence, but I expect what happens is if you delete a base then you get a frame shift, which will adjust the position of the stop codon. If any or none of that makes sense then let me know and I can explain in greater detail
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#3
(Original post by AortaStudyMore)
it won't be anything to do with that specific sequence, but I expect what happens is if you delete a base then you get a frame shift, which will adjust the position of the stop codon. If any or none of that makes sense then let me know and I can explain in greater detail
Yes I understand the idea behind this. Please explain it in greater detail. Thanks!!
0
2 years ago
#4
(Original post by algebrax1)
Yes I understand the idea behind this. Please explain it in greater detail. Thanks!!
Okay, I'm assuming that in your original question that the sequence of bases is much longer and that the codon after the last one in your sequence is one of 3 stop codons. Hence why the polypeptide is only 4 amino acids long. Now as I can't remember your sequence of bases, I'm just going to make some up:

ATG-CTT-TCC-AAT-TAG-CAC-TAC-TCG-ATA-CAA-TCA-CTA-CCC-CGA-TTG-ATA-GAC-NNNNNNNNNNN

(The N's just mean "any base")

Right, the TAG is the stop codon, so in this sequence, only 4 amino acids will be coded for. Now, I've included the dashes because these represent "frames", this just means that ATG is a codon, CTT is a codon, TCC is a codon etc. Okay, now if we delete the 3rd base from the left, we're left with this sequence:

AT_-CTT-TCC-AAT-TAG-AAA-TAA-TGG-ATA-CAA-TCA-CTA-CCC-CGA-TTG-ATA-GAC-NNNNNNNNNNNN

in reality however, when a base is deleted, there is a "frame shift", where the codons are instead read as ATC, TTT, CAA etc, ie the sequence will look like this:

ATC-TTT-CCA-ATT-AGA-AAT-AAT-GGA-TAC-AAT-CAC-TAC-CCC-GAT-TGA-TAG-ACN-NNNNNNNNNNN

This just shows that all of the bases have now shifted one to the left, so you're left with a whole different code because most of the codons have now changed as a result of the shift.

This also shows that instead of the TAG stop codon being after the 4th codon, it is now after the 5th codon, hence you get a 15 amino acid polypeptide forming instead of a 4 amino acid peptide forming.

I hope that clears things up
0
2 years ago
#5
that should say "after the 15th codon" not "after the 5th codon" at the end
0
2 years ago
#6
(Original post by algebrax1)
Base sequence is
GCACCCATATGG
This makes amino acids arginine-glycine-tyrosine-asparagine (in order)

Explain why a mutation that deletes the base found in position X (third A from the left) will result in the production of a polypeptide which is 15, as opposed to 4 amino acids long.

I have no idea! Thank you!!
It's 'read' in 3's that means a sort of leap year effect happens and it must be read 15 times to reach the end of then 'sentence' and must stop on TGG so that asparagine is the last peptide bond in the chain. The endings can have roles as markers, for digestibilty or shape for whatever reason as the residual group will be different than the other 19 amino acids which must give it different properties. Maybe for attachment to the surface of a membrane? But this seems to me like the most plausible answer.
0
2 years ago
#7
(Original post by Anfanny)
It's 'read' in 3's that means a sort of leap year effect happens and it must be read 15 times to reach the end of then 'sentence' and must stop on TGG so that asparagine is the last peptide bond in the chain. The endings can have roles as markers, for digestibilty or shape for whatever reason as the residual group will be different than the other 19 amino acids which must give it different properties. Maybe for attachment to the surface of a membrane? But this seems to me like the most plausible answer.
It doesn't work like that, the ribosome isn't going to continue making a protein until it reaches an amino acid that should be at the end of the polypeptide, it's going to continue until it reaches a stop codon and then chuck out whatever has been made. Besides, regardless of whether the last amino acid in the chain is asparagine or not, the whole polypeptide chain is messed up because of the addition of 11 other amino acids that shouldn't be there.
0
2 years ago
#8
(Original post by AortaStudyMore)
It doesn't work like that, the ribosome isn't going to continue making a protein until it reaches an amino acid that should be at the end of the polypeptide, it's going to continue until it reaches a stop codon and then chuck out whatever has been made. Besides, regardless of whether the last amino acid in the chain is asparagine or not, the whole polypeptide chain is messed up because of the addition of 11 other amino acids that shouldn't be there.
True that make's sense unless they are side by side the ribosome can travel along a DNA strand but for protein synthesis they work as a continuous friends that goes beside the next like a conveyor belt.
0
2 years ago
#9
(Original post by Anfanny)
True that make's sense unless they are side by side the ribosome can travel along a DNA strand but for protein synthesis they work as a continuous friends that goes beside the next like a conveyor belt.
Yh that may be, but that doesn't prove your point in any way... haha :P
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2 years ago
#10
(Original post by AortaStudyMore)
Yh that may be, but that doesn't prove your point in any way... haha :P
I know how is it meant to get that long for no reason. It's wrong but it's not random lol
0
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