Mutations Flashcards
What kind of mutation has no effect on the offsprings of an organism?
Somatic mutation: Only occurs in the daughter cells of the mutant cell.
What kind of mutation affects the offsprings of an organism? How can this be an advantage?
Germinal mutations occur in germ-line cells (cells that undergo meiosis) and can be passed to the next generation. They provide diversity to the genetic material and are thus a key to evolution.
What changes in a mutation?
The DNA … NOT THE RNA. DNA is the template that is altered to then make another RNA.
What are silent mutations
They are mutations that change a base nucleotide of DNA so as to change the RNA codon, but do not change the amino acid for which it codes. Hence, there is no apparent change in the protein. It also happens if a new amino acid does not change the protein, but not for our course.
What are missense mutations?
They are mutations that change a base nucleotide to the DNA and thus makes the RNA codon code for a different aa.
What are non-sense mutations?
They are mutations that change a base nucleotide on the DNA and make the RNA codon a stop codon. They are the most harmful when they occur at the beginning of the mRNA (near 5’ end thus 3’ end of the DNA) because it makes the polypeptide chain significantly shorter.
What are the types of frameshift mutations? Are they all equally harmful/damaging?
There are insertions and deletions of either 1-2-3 base pairs. When 1 or 2 base pairs are added or deleted, all of the mRNA chain shifts so that all subsequent amino acids are potentially different ones. They are the most harmful when they are at the beginning of a polypeptide chain (near 5’ end thus 3’ end of the DNA) because everything that follows is also altered. The 3 base deletion/insertion is not that harmful because it does not cause a frameshift. Moreover, all of that depends if the mutation occurs in an exon or an intron. If it is an intron, the effect of a triple insertion or deletion is almost null. (3= also multiples of 3, same for others… 8 = double deletion/insertion). It does not have any effect if it is in an intron.
What are the causes of mutations?
They occur either during DNA replication spontaneously as results of the chemistry of DNA and enzymes. They can also come from exposure to diverse mutagens like radiation or chemicals.
How can you determine if the effect of a mutation will be important or not and if it could kill the cell?
First, it depends on the place where the mutation occurs. If it is at the beginning of the polypeptide chain (near 5’ end of the mRNA, 3’ end of DNA), frameshifts or non-sense mutations can have a considerable effect. The frameshifts mutations also depend on whether it happens on an exon or an intron. In an intron, it would have no effect on aas because these are removed when pre-mRNA is processed.
What is the role of a mutagen?
When cells are exposed to mutagens, it produces mutations in the DNA in a process called mutagenesis. We say that the cells are thus mutagenized,
