Biology 3594A Lecture Notes - Lecture 5: Synonymous Substitution, Transfer Rna, Retrotransposon
13 May 2018
School
Department
Course
Professor
Exogenous agent and its mutagenicity –need to know something about the experience of that organism, from outside
Endogenous –spontaneous
Within organism, ROS and stress, mitochondrial function
Mutation frequencies might be high
Spontaneous –arose without the intervention of the scientific investigator or the movement of the animal into an environment with the intent to cause a change
Range -
Copy number –if CNVs, 500 nucleotides, can be smaller (50)
Beyond single nucleotide
Relate to strings of sequence that expand and contract in number
Tend to have a unit (dinucleotides or trinucleotides or longer)
Mobile elements
Copy paste or cut paste mechanism
Copy paste –retrotransposon
Transposon –deletion at one site and insertion at another site
Tend to be viral
Slide: smaller to larger units
Neomorph –new
For gain and loss, there isn’t just one outcome
Neomorphic usually rare
More hypomorphic and amorphic than there is hypermorphic overall
Whenever you see insertions you tend to see that it’s inserting what you’ve seen before in the sequence, like a stutter that’s increasing
Deletions tend to be more frequent insertions for spontaneous mutation
Insertions tend to be increasing, creating a run (see first point)
Silent change –nothing at phenotypic level because we haven’t changed the amino acid, protein should not work any differently
Synonymous substitution –same in meaning
At a protein level, two molecules would not be different
tRNAs that contain anticodon for this are different, they have different abundances
If tRNA with anticodon for CGC is limiting, you could come to a hypomorphic situation
When tRNA abundances have imbalances and biases (which they do), if you were working in the lab and looked at protein abundance you would see a difference
Sometimes an individual might still have a hypomorphic phenotype related to tRNA abundance
Diagnostic odyssey –families looking for genetic diagnosis
Imbalance in tRNA abundance may not come up right away
Acidic vs basic, non-polar vs polar, small vs large, or at a crucial spot
Conservative substitutions are better, less difference
Regulatory site –don’t need to think about codons, just think about all of the things that were supposed to bind that can’t bind
Hypermorph and hypomorph, can shut it off to amorphic situation
Ex. Runs of As, difficult for a polymerase to get the number exactly right, slippage and deletions and insertions
Also duplicated whole genes that diversified in function
Can have a particular type of mutation: C to T, spontaneous deanimation
G and As are falling out of DNA sequences, depurinic sites
Hotspot: people have similar mutations, not because they’re related but because that nucleotide has a high mutation frequency
Greater probability of a mutation occurring in a particular spot
Lec 5 Mutation Review
May 13, 2018
12:00 AM
3594 Page 1
Document Summary
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