Biology 3594A Study Guide - Final Guide: Pyrimidine, Purine, Mutagen
13 May 2018
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Lecture 5 Flashcards
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2 origins of gene mutation
- Name
- Frequency
- possible causes
1. Endogenous (spontaneous)
- frequency is 10^-5 to 10^-8
- possible causes: cell metabolism, DNA chemistry
- usually a deletion
2. Exogenous (induced)
- frequency is dose dependent
- possible causes: mutagen exposure, environmental exposure
Spontaneous mutation
Arose without intervention of scientific investigator or
movement of the animal into an environment with the intent
to cause a change
3 categories of gene mutation
1. A change in one nucleotide
2. a change in copy number
3. Insertion of a mobile element
Change in one nucleotide (3)
- Substitution
- Deletion (more frequent than insertions for spontaneous
mutation)
- Insertion (usually increasing stutter, inserting what you've
seen before, creating a run)
Change in copy number (2)
Strings of sequence, tend to have a unit
- repeat expansion
- repeat contraction
Insertion of a mobile element (2)
- transposons (cut paste, deletion at one site and insertion at
another)
- retrotransposons (copy paste)
Tend to be viral
Larger units than copy number change
Gene mutation: 2 consequences and
their frequency
1. Loss of function (most frequent)
2. Gain of function (rare)
2 Types of loss of function
- Hypomorphic: reduced function
- Amorphic: eliminated function
2 Types of gain of function
Hypermorphic: enhanced function
Neomorphic: alternate function
Transitions
- Purine to purine or pyrimidine to pyrimidine
A to G or G to A
C to T or T to C
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Arose without intervention of scientific investigator or movement of the animal into an environment with the intent to cause a change: a change in one nucleotide, a change in copy number, insertion of a mobile element. Deletion (more frequent than insertions for spontaneous mutation) Insertion (usually increasing stutter, inserting what you"ve seen before, creating a run) Strings of sequence, tend to have a unit. Transposons (cut paste, deletion at one site and insertion at another) Gene mutation: 2 consequences and their frequency: loss of function (most frequent, gain of function (rare) Purine to purine or pyrimidine to pyrimidine. No change in amino acid or phenotype aka synonymous substitution. *unless hypomorphic phenotype related to trna abundance trnas have different biases in abundance. If the mutation messes up a trna for an anticodon that is limiting, could end up with a hypomorphic phenotype (difference in protein abundance) Aka nonsynonymous mutation: conservative (similar amino acid)
