Mutation Flashcards
are segments of DNA located on chromosomes.
Genes
is a permanent change of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements. It results in damage to DNA that is not repaired or to
RNA genomes (typically caused by radiation or chemical mutagens), errors in the process of replication, or from the insertion or deletion of segments of DNA by mobile genetic elements
Mutation
is defined as an alteration in the sequence of nucleotides in DNA. This change can affect a single nucleotide pair or larger gene
segments of a chromosome.
Gene Mutation
Gene mutations can be generally
categorized into two types:
point mutations and base-pair insertions or deletions.
are types of gene mutations, such as those affecting a small gene in one or a few nucleotides. There are 2 types of gene mutations: Point Mutation and Frame-Shift Mutation.
Small scale mutations
is the change of a single nitrogen base in a DNA sequence. It is
usually the least harmful type of DNA mutation.
Point Mutation
This happens when a point mutation causes a single nitrogen base in a codon for one amino acid in the protein glutamic acid to code for the amino acid valine instead. This single small change causes a normally round red blood cell to instead be sickle shaped.
Anemia
These are type of change that does not alter the sequence of a protein because of the redundancy of the genetic code (the new triplet codes for the same amino acid as the original triplet),
or because it affects an area not coding DNA or an intron.
But this change can still have serious consequences on the phenotype. Indeed, the change of a single nucleotide can change the splice donor site, without changing the amino acid sequence. This may, therefore, result in a deletion of an entire exon of the peptide sequence, the exon is not recognized because the splice site has been mutated. A synonymous mutation means a silent mutation that affects exon, without changing the protein sequence.
Silent Mutation
This point mutation results in the replacement of one nucleotide by
another. In some cases, this change causes a change in the amino acid encoded, which may or may not have an impact on the function of the protein produced by the gene in the case of a gene encoding, or the affinity for a transcription factor, in the case of a promoter region of the DNA.
We speak of mutation transition when there is a substitution of a purine base to another base purine (or pyrimidine
base to another pyrimidine base). In contrast, a mutation transversion is a mutation caused by the
replacement of a purine by a pyrimidine base (or pyrimidine base by a purine base).
Missense Mutation
Change of a nucleotide causes the replacement of a codon specifying an amino acid by a stop codon. This results in the production of a truncated protein
Nonsense mutation
are generally much more serious and often more deadly than point mutations. Even though only a single nitrogen base is affected, as with point mutations, in this instance, the single
base is either completely deleted or an extra one is inserted into the middle of the DNA sequence. This change in sequence causes the reading frame to shift
Frame-shift Mutation
add one or more extra nucleotides into the DNA. They are usually caused by transposable elements, or errors during the replication of repeating elements (e.g., AT repeats). These in the coding
region of a gene may alter splicing of the mRNA (splice site mutation), or cause a shift in the reading frame (frameshift mutation), both of which can significantly alter the gene product. Insertions can be reversed by the excision of the transposable element.
Insertion
mean removing one or more nucleotides from the DNA. Like insertions, these mutations can alter the reading frame of the gene. In general, they are irreversible: Though exactly the same
sequence might, in theory, be restored by an insertion, transposable elements able to revert a very short _____ (say 1–2 bases) in any location either are highly unlikely to exist or do not exist at all.
Deletion
a mass of genetic material consisting of DNA that is tightly coiled
around proteins called
Histones
A ____________ is single-stranded and is comprised of a centromere region that connects two arm regions.
Non-duplicated chromosome
short arm region
p arm
long arm region
q arm
The joining of a fragmented chromosome to a non-homologous chromosome. The piece of chromosome detaches from one chromosome and moves to a new position on another chromosome.
Translocation
This mutation results from the breakage of a chromosome in which the genetic material becomes lost during cell division. The genetic material can break off from anywhere on the chromosome
Deletion
are produced when extra copies of genes are generated on a chromosome.
Duplication
the broken chromosome segment is reversed and inserted back into the chromosome.
Inversion
If the inversion encompasses the centromere of the chromosome, it is called a
Pericentric Inversion
If it involves the long or short arm of the chromosome and does not include the centromere, it is called a
Paracentric Inversion
This type of chromosome is produced by the improper division of the centromere. Contain either two short arms or two long arms. A typical chromosome contains one short arm and one long arm.
Isochromosome
