Ch 7 Exam 2 Flashcards
(62 cards)
Mutations
changes in nucleotide sequence of DNA
spontaneous or induced
Spontaneous damage to DNA
Natural process in cells, DNA replication errors, or from reactive oxygen species from metabolism
Induced mutations
due to mutagen. Any chemical or physical agent that causes an increased in rate of mutations above the spontaneous background
Mutations can be good
widen the gene pool and offer genetic variations
rarely adventageous
Deleterious mutation
bad mutations, more common than advantageous mutation,
Point mutations
one substituation nucletodie
More trastic
expansion of trinucleotide repeats
insertion/deletions
major chromosomal rearrangements
transposable elements
are they random or are there places where they are more common
Hotspots for mutations
Transition mutations
replace one pyrimidine for another or a purine for antoher
transversion mutations
replace a pyrimidine w a purine or vice versa
Silent mutation
one base change but it doen’t change the amino acid sequence
missense mutation
one base change but amino avid changes
nonsense mutation
one base change and equals stop codon
example of missense mutation
sickle cell anemia
A to T transversion
Insertions and Deletions
-multiples of 3 in protein coding gene, either adds or sbutracts amino acids
-not a multple of 3 ends up changing the reading from
cystic fibriosis
deletion of one codon leading to one amino acid not being incoded
frame shift mutations
one base out changing the entire reading frame. everything after mutation changes the reading frame. taysacks disease. THyroid hormone RTH.
Whether or not a nucleotdie substitution hasve a phentypic effect depends on the
what type of mutation
do they alter a critical nucleotide in a gene regulatory region
do they alter a critical nucleotide in the template for the functional RNA molecule
Trinucleotide repeats lead to genetic instability
slip structures. Friedreich ataxia.
when two chromosomes pair up but don’t line up because there’s so much repeating can lead to
unequal crossing over
Types of mutations
deletion, duplication, inversion, nonreciprocal translocation, reciprocal translocation
Three classes of DNA damage from mutagens
single base changes, structural changes,
What are the three types of damage to DNA by mutagens and what is the first one
Single base change, strucural distortion, DNA backbone damage
Single base change: conversion affects the DNA sequence
only a minor effect on overall structure
Deamination - most frequent and important kind of hydrolytic damage. Removes an amine
Aklylation - adds an aklyl group
Oxidation - adds oxygen to the base
Deamination
an amino group is removed from a molecule. Single base changes
