mutations

mutations

• heritable changes in genetic info
  2 types: gene mutations(only genes)
  chromosmal mutations ( whole chromosomes)
• most mutations unoticable
• some have little effect, some have a lot

Point mutations

• gene mutations that involve changes in one or a few nucleotides
• occur at single point in DNA sequence

spontaneous mutations

• most genetic mutations result from these errors in genetic processes (DNA replication, etc.)

substitution

• type of mutation where one base is changed to different base
• usually only affects single amino acid in sequence

Frameshift mutations

• insertions and deletions
• shift "reading frame" of genetic message
• affect entire sequence
• codons get grouped wrong

induced

• caused by mutagens

mutagens

• chemical or physical agents in environment
• uv, radiation, pollutants, etc.

harmful mutation

• change protein structure and gene activity
• can cause cancer
• some don't damage organism health but make it harder to survive

helpful mutation

• change in protein structure that benefits organism
• example: polyploidy (extra set of chromosomes)
  • in plants -> stronger, larger, more seeds

neutral/silent mutations

• have no effect of organism phenotype
• can occur between genes
• can occur within genes but not create change - "wobble effect" (multiple codons coding for same amino acid)

gene mutation

• single gene mutated

chromosomal mutations

• whole chromosome

types

• nondisjunction
• monosomy
• trisomy
• deletion
• duplication
• inversion
• translocation

nondisjunction

• chromosomes fail to seperate properly
• meiosis II - primary nondisjunction
• meiosis II - secondary nondisjunction

monosomy

• (2n-1)
• individual only has 1 allele of a chromosome
• e.g. tuner syndrome (monosomy of X chromosome)

trisomy

• type of nondisjunction
• (2n+1)
• individual has 3 alleles of a chromosome
• e.g. down syndrome

deletion

• segment of entire chromosome gone

duplication

• more than one segment or whole chromosome has repeat

inversion

• segment of chromosome flipped 180 degrees

translocation

• segment of chromosome moves to other chromosome
• not same as crossing over

karotype

• visual displey of chromosomes arranged by size, shape, and banding pattern