Mutations and Chromosomes part 1
mutations that affect cell characteristics: loss of function
affect ability of a gene to code for correct working protein; typically recessive
base insertion or deletion (frameshift mutation)
alter reading frame of mRNA triplets
mutation
any permanent change in an organism's DNA
nonsense mutation
changes codon for an amino acid to STOP codon polypeptide chain will be too short; protein will likely be non-functional
missense (replacement) mutation
changes one amino acid to another
silent mutation
does not alter amino acid sequence (due to redundancy in genetic code)
tautomerism
each nucleotide base can exist in two different forms; different forms= different base pairing patterns
Are mutations always harmful? coding region of DNA- mutations may be:
harmful, neutral, beneficial-provide genetic variation (source of new alleles); may increase an organism's ability to adapt to environment
Are mutations always harmful? non-coding region of DNA-mutation may be:
not have an effect, alter gene expression (if it occurs within regulatory DNA)
somatic mutations
occur in body(non-gamete) cells; not inherited by offspring
germline mutations
occurs in cells that produce gametes; inherited by offspring
chromosomal mutations
rearrangement or deletion of portions of chromosomes
point mutation
replacement of one nucleotide with another
Gain-of- function
results in production of protein with altered function; typically dominant
mutation that does not alter cell characteristics
silent mutation