dna mutations

mutations occur

randomly and spontaneously

spontaneous

errors in replications

induced

forced by mutagens

base mismatch cause

replication, stress

single strand break

Oxygen radicals, radiation, chemotherapy

double strand break/interstrand linkage

radiation, chemotherapy

Germ line/gametic mutations

provide new alleles to gene pools

evolutionarily significant

somatic mutations

occur in body tissues and are not passed on

Why do gametic mutations not affect the host?

Only affect germ line cells (gametes) which don’t get expressed until conception.

3 changes that occur to mRNA after transcription that occurs in eukaryotic cells

Introns removed

5 cap added

poly tail added

point mutations

occur with only a small number of nucleotides

types of point mutations

substitutions

insertions/deletions → frameshifts

chromosomal mutations

affect chromosomes and therefore body on a larger scale

types of chromosomal mutations

deletions of big chunks of chromosomes

swapping sections

inversions (flips od DNA sections)

3 possible OUTCOMES

1) Silent - no sequence change (neutral)

2) missense - new aa (could be all)

3) nonsense - early STOP codon (usually bad)

philadelphia translocation

genes exchange info/cross over on nonhomologous chromosomes

some gene mutations do not affext phenotype because

they may be silent in non-coding regions, or not affect protein formation/active site