19.1 mutations and variation Flashcards
what is a mutation?
change in the sequence of bases in DNA
how is protein synthesis affected by a mutation?
the wrong bases and transcribed which means that translation would lead to the wrong amino acids being produced and thus a different primary structure of a protein
so the final 3D structure may change
what are the three types of mutation?
substitution
deletion
insertion
what is a substitution mutation?
when a nucleotide is substituted for another which leads to a different codon
when can a substitution mutation lead to no change?
when the codon replacing the original codon codes for the same amino acid and so the same protein is produced
DEGENERATE NATURE OF GC
what is a deletion mutation?
when one or more nucleotides are removed
what is an insertion mutation?
when one or more nucleotides are added
what does insertion and deletion lead to?
a frameshift mutation
what is a frameshift mutation?
by adding or removing a nucleotide, you displace the following codons which, due to the non-overlapping nature of the GC, changes every successive codon
so changes the base sequence
what are the 3 effects of a mutation?
no effect
damaging
beneficial
no effect
mutation causes no effect on the phenotype of an organism
damaging
mutation causes major change to an organism’s phenotype which prevents essential processes
beneficial
mutation causes a change to an organism’s phenotype which provides an advantageous characteristic
when can a mutation have no effect?
mutation changes a base in a codon but the codon stays the same so the same amino acid is translated
mutation changes a base in a codon and a different amino acid is translated BUT the new amino acid is chemically similar to the original so functions very similarly
how do mutations occur?
spontaneously during DNA replication
