Mutations + Gene Editing D1.3 Flashcards
What is a gene mutation?
a permanent, random and structural change in the base sequence of DNA.
What are the two main types of mutations?
point mutation
frameshift mutations
What are the different types of point mutation?
- silent base substitution
- missense base substitution
- nonsense base substitution
What is silent base substitution?
changed codon sequence does not change amino acid it codes for because of degeneracy of genetic code.
What is missense base substitution?
subsitution could cause expression of different amino acid, the polypeptide is either functional or dysfuntional depending on the amino acid
What is nonsense base substitution?
the substituted base is a stop codon resulting in a shortened polypeptide. may still be functional
What are the consequences (examples) of point mutation?
- point mutation in the HOX gene of fruit fly causes legs to grow where the antennae is supposed to
- sickle cell anemia
What is frameshift mutation?
insertion deletion: the entire reading frame is changed and often results in a polypeptide ceasing to function.
What are the consequences (examples) of frameshift mutation?
- CCR5 gene deletion resulting in resistance to HIV
- HTT gene coding for Huntington protein resulting in more repeated CAG codons than necessary and a neuronal degeneration.
How much of the human body is made of non-coding DNA? What does this mean for mutations?
98% of the body. if a mutation occurs in the non-coding region of DNA, base sub is unlikely to have any effect.
Causes of gene mutations?
errors in DNA repair or replication and mutagens
What are the mutagens?
- radiation
- chemicals
- infectious agents
What does radiation do in mutations? What do the frequencies mean?
increase mutation rate.
higher frequency (shorter wave_ = more dangerous
What are somatic cells?
body cells used to produce specialized cells. (diploid)
What are germ cells?
reproductive cells used to produce sex cells. (haploid)
