Mutations in Molecular Genetics Flashcards
What are polyribosomes?
A cluster of ribosomes that simultaneously translates the mRNA molecule.
An example of a mutation would be sickle cell disease. What is this?
A genetic mutation in which the red blood cell is a crescent shape, not a circle, interfering with the transportation of oxygen.
What is a point mutation?
A mutation in which the wrong nucleotide is substituted in for the right nucleotide. Base pair substitution.
What is the molecular basis for sickle cell disease?
A point mutation occurs in which adenine is substituted for thymine in the DNA. The codon becomes GUA instead of GAA, producing the sickle-cell hemoglobin, Val, instead of the normal hemoglobin, Glu.
What is a mutagen?
Something that causes a mutation, like radiation.
What happens when a cell is exposed to too much radiation?
The DNA can fall apart.
True or false: It is normal to have small changes in the strand during translation.
True.
Does point mutation always have an effect on the production of amino acids? Give an example.
No, it does not always have an effect. For example, if the codon GGC somehow becomes GGU instead, it will still produce the amino acid Gly.
What is missense for point mutations?
One point mutation that creates a change in the amino acid sequence.
Give an example of missense for point mutations.
If the codon was supposed to be GGC, but adenine was substituted for guanine resulting in AGC, the amino acid will be Ser, not Gly.
What is nonsense for point mutations?
One point mutation that creates a stop codon, resulting in an unfinished protein that is not functional.
What is an example of nonsense for point mutations?
AAG produces the amino acid Lys, but if the first adenine is substituted for uracil resulting in the codon UAG, it becomes a stop codon.
What is a frameshift mutation?
The insertion or deletion of a base pair, often causing extensive missense but sometimes causing nonsense.
What is an example of a frameshift mutation causing extensive missense?
If the sequence UUUGGCU loses a U to become UUGGCU, the resulting amino acids will be Leu and Ala instead of Phe and Gly.
What is the difference between missense from point mutations and extensive missense from frameshift mutations?
Point mutations can cause missense that only affects one codon and one amino acid, but frameshift mutations can cause extensive missense that messes up the rest of the sequence.
