Mutations 2D Flashcards
Deletion
occurs in a broken segment is lost from a chromosome
Duplication
A segment is broekn rom one chromosome and inserted to its homologue
Translocation
Occurs if a broken segment is attached to a diferent nonhomologous chromosome
Inversion
Occurs if a broken segmet re-attaches to the same chromosome from which it was lost but in reversed orientation so that the order of genes is reversed
in one chromatid
Inorder to be inherited by offsprings, chromosomal alterastions must occur
in cells of the germ line leading to devlopment of eggs or sperm
When can duplications arise
during recombination in meiosis if crossing over occurs unequally so that a segment is deleted from one chromosome of a homologous pair and inserted into the other
In many cases, a transloaction is_____ meaning that……
reciprical
two nonhomologous chromosomes exchange segments
reciprical translocations resemble ***** except that the two chromosomes invloved in the exchange **
genectic recombination
do not contain the same genes
Inversions have the same affects as
translocations
Missense mutation
A sense codon is changed to a different sense codon that specifies a different amino acid.
Nonsense mutation+what happens in translation
A sense codon is changed to a stop codon. Translation of an mRNA containing a nonsense mutation results in a shorter than normal polypeptide that in many cases will be only functionally partially at best.
Silent mutations
A sense codon is changed to a diferent sense codon but that codon still specifies the same amino acid so the function of the polyptide is the same.
frameshift mutation+ what about resulting polypeptide?
A single base pair deletion or insertion in the coding region of a gene alters the reading frame of the resulting mRNA.
The resulting polypeptide is usally nonfunctional because of the signifigantly altered amino acid sequence.
Mutations
Changes in double stranded sequence of bases in genetic material
Spontaneous mutations
changes in DNA due to errors in replication and repair
Thymine dimers
Thymine bases that are side by side in a chromosome become linked together covalently, Attempts to fix the dimers can lead to mutations.
somatic mutations are usually expressed as
sectors
If a mutation occurs in one of the progenitor cells, all of its daughter cells will also express the mutation. For this reason, somatic mutations generally appear as a sector on the mutated individual.
transitions
a point mutations that changes purine to another purine or pyrimidine to another pyrimidine
Transversions
Point mutation of purine to pyrimidine or pyrimidine to a purine change.
Frameshift mutation
insertion or deletion of a small number of base pair that alter reading frame. Unless in mutations of threes
spontaneous lesions
Depurination and deamination (*cytosine lose amine group and becomes uracil) of bases
Induced
natural environment or articifial agent or mutagen
