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BossMan300 BossMan300
wrote...
Posts: 40
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9 years ago
What is the difference between transversion point mutations and misspairing point mutations?
I was watching:
https://www.khanacademy.org/test-prep/mcat/biomolecules/genetic-mutations/v/the-causes-of-genetic-mutations
at 1:51
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wrote...
Educator
9 years ago
transversion point mutations

This is when a base changes, G becomes either A, T, or C.

misspairing point mutations

This is when a base is lost, causing everything to shift, either left or right (AKA Slipped strand mispairing)

BossMan300 Author
wrote...
9 years ago
Do you have a source for the misspairing point mutations?

I know that two main types of mutations are point mutations and frame shift mutations.  It seems like you are describing a mutation in which the entire sequence shifts; I believe this would be a frame shift mutation.

According to the attached graphic a tranversion is:

A (2 rings) was mutated to Rightwards Arrow  C or T (1 ring)
G (2 rings) was mutated to Rightwards Arrow  C or T (1 ring)
C (1 ring)   was mutated to Rightwards Arrow  A or G (2 ring)
T (1 ring)   was mutated to Rightwards Arrow  A or G (2 ring)

Note: the ring pattern [2 Rightwards Arrow 1 or 1 Rightwards Arrow 2]
I believe misspairing is when:

G should pair with C but instead it pairs with T which is the same type, pyrimidine [C,T]
A should pair with T but instead it pairs with C which is the same type, pyrimidine [C,T]
C should pair with G but instead it pairs with A which is the same type, purine [A,G]
T should pair with A but instead it pairs with G which is the same type, purine [A,G]

Hopefully that makes sense, I was originally confused with the notation used in the video.
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wrote...
Educator
9 years ago
I got it from the source outlined below:

Mispairing refers to the presence of at least one nucleotide in one strand of a DNA molecule, which is not the complement of the nucleotide at the corresponding locus in the other strand.

Slipped strand mispairing occurs during DNA replication. Regions of DNA that are capable of assuming hairpin-like secondary structures are particularly prone to this error because displacement of the strands disrupts alignment of bases. Mispairing results in the repeated replication of the same stretch of DNA, and provides an explanation for satellite DNA.

Deletion and insertion mutations, indels, often occur in repetitive sequences. For example, deletion of "AT" from the sequence "ATAT" in the CFTR gene. Such mutations are most often caused by a "replication slippage", where the new strand mispairs with the template strand at repetitive sequences.
Source  http://mechanismsevo.blogspot.ca/2007/11/mispairing.html
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