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