Biology mutation help (1 Viewer)

ayion

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In point mutation, i don't get the difference between substitution and frameshift. In substitution, its defined as one nucleotide being replaced by another nucleotide and in frameshift, its defined as one or two nucleotides being added or removed. I don't get how tell which ones which if they both can have one nucleotide being removed?
 

mikrokosmos

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Correct me if I'm wrong - I think substitution is when although the mutation is present, it still codes for the same amino like in the image I have attached, whereas frameshift is an overarching term for addition and deletion where the WHOLE reading frame is shifted. The other type is point mutation, which involves substitution, deletion, insertion and inversion.

 

Thomas Aquilina

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In point mutation, i don't get the difference between substitution and frameshift. In substitution, its defined as one nucleotide being replaced by another nucleotide and in frameshift, its defined as one or two nucleotides being added or removed. I don't get how tell which ones which if they both can have one nucleotide being removed?
Consider the DNA sequence ...ATC GTC AGT...
A substitution mutation is simply where one of those bases is replaced for another. So, for example, a substitution mutation in this sequence might be ATC GAC AGT, where an A has replaced the middle T. Only one codon has changed - the rest are the same
In the case of frameshift mutations, multiple codons are changed because a base is either taken out or inserted. For example, if the 2nd base in the given sequence (T of ATC) is removed, we are left with the sequence ...ACG TCA GT... Notice how taking out a singular base has changed the base composition of every codon after it. This is why frameshift mutations are much more likely to have an effect on the organism (because its more likely changing a heap of codons impacts cell function over one changed codon) when compared to substitution mutations
 

Thomas Aquilina

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Correct me if I'm wrong - I think substitution is when although the mutation is present, it still codes for the same amino like in the image I have attached, whereas frameshift is an overarching term for addition and deletion where the WHOLE reading frame is shifted. The other type is point mutation, which involves substitution, deletion, insertion and inversion.

Substitution mutations are more likely to result in no effect (where the amino acid stays the same on the protein level) but that isnt always the case. Inversion is a chromosomal mutation too
 

fruitpunch

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In substitution the base is substituted with a different nucleotide base
nothing gets removed in substitution mutations.
while frameshift can be either insertion (addition) of a base or deletion of a base.
 

Eagle Mum

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Correct me if I'm wrong - I think substitution is when although the mutation is present, it still codes for the same amino like in the image I have attached, whereas frameshift is an overarching term for addition and deletion where the WHOLE reading frame is shifted. The other type is point mutation, which involves substitution, deletion, insertion and inversion.

What you’ve shown is true, but not the complete picture.
Substitution of the cytosine nucleotide (C) could just as likely have been to a G or A.
The possible resultant mRNA triplets could have been AAC or AAT, either of which would have produced an amino acid change from lysine to asparagine.

The effect of an amino acid change depends on how closely the amino acid characteristics in different groups overlap (the Venn diagram below is useful) and where in the protein structure the change has occurred.
1637237645251.jpeg
 

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