hgheith
Forum Elite
Topics: 39
Posts: 268
|
 A point mutation in what base position of a codon would least affect the Amino Acid expressed?
A protein has 100 amino acids, a mutation occurs. The first 15 are ok, 16-26 are incorrect, and the rest are missing, what mutation and where?
|
| mash
Forum Fanatic
Topics: 147
Posts: 1,326
|
1 3rd base
2 mis sense mutaion(46th base)
___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius
|
| Sakaki-
Forum Senior
Topics: 1
Posts: 238
|
A point mutation at the third position of the codon (at the 3' end) would least affect the amino acid expressed.
I believe that that is a missense mutation at position 46, as it results in premature termination of translation.
Edit: Heh--same time, mash. 
|
| rida
Forum Guru
Topics: 109
Posts: 721
|
Can you guys explain how you got 46??
___________________
"If He takes you to it, He'll take you through it."
|
| mash
Forum Fanatic
Topics: 147
Posts: 1,326
|
bcoz 1st 15 aa r normal=>15*3=45 bases wud be normal
16th -26th aa r abnormal so, mutation may be in 46th or 47th base(3rd base wont make any diff)
___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius
|
| rida
Forum Guru
Topics: 109
Posts: 721
|
THANX A MILLION MASH!!!!
___________________
"If He takes you to it, He'll take you through it."
|
| hgheith
Forum Elite
Topics: 39
Posts: 268
|
3rd position b/c of redundancy
it would be a frameshift mutation in the 16th amino acid (or I guess the same as 46th base)
Frameshift :arrow: deletion or addition of a base, the effect on the protein :arrow: usually nonfunctional; often shorter than normal.
|
| mash
Forum Fanatic
Topics: 147
Posts: 1,326
|
d'oh! u r right it shud be frameshift mutation coz missense wud lead to change in 1aa at 16th position(if base change is at 46th)....
___________________
I hear and I forget. I see and I remember. I do and I understand.
--Confucius
|
| Sakaki-
Forum Senior
Topics: 1
Posts: 238
|
So if a frameshift mutation leads to a termination codon somewhere later in the protein (as in not the first codon in which the mutation occurs), is it still considered a frameshift mutation and not a missense mutation?
|
| hgheith
Forum Elite
Topics: 39
Posts: 268
|
A missense mutation only specifies a different aa, not a stop codon (that would be a nonsense mutation) so it does not affect the length, only the function.
With a missense mutation there is only a change in the amino acid with the base that was mutated, but the rest would be the same as in Sickel cell: normally it's GAG at the 6th position in the betaglobin gene which codes for glutamic acid, with the disease it's mutated to GTG which now specifies valine, but the rest of the codons remain the same.
hope that helps.
It does make sense that a frameshift mutation would cause a nonsense mutation down the line, so I guess that is possible :roll:
|
| Sakaki-
Forum Senior
Topics: 1
Posts: 238
|
Thanks, hgheith, for the clarification.
|
|
| |
| | | | | | | | | | | |
