Mutations

Any change to an organisms DNA

Occurs in somatic cells Not heritable - won’t affect offspring Only the cell where the mutation occurred will be affected

Occurs in gametes/ cells that make gametes Heritable - will affect offspring

When homologous chromosomes or sister chromatids do not to separate when they are supposed to

Results in somatic cells or gametes with an incorrect number of chromosomes Aneuploidy !!!

A condition where an individual has an Incorrect number of chromosomes (One extra/ missing)

A condition where an individual has extra/missing SETS of chromosomes More than 2 complete sets of chromosomes

When an individual has 3 copies of chromosomes instead of 2 (1 extra)

When an individual has 1 copy of chromosomes instead of 2 Missing 1

Look whether • male/female ? • monosomy/ trisomy ?

Turners Syndrome

Klinefelter’s Syndrome

Monosomy and trisomy

Anaphase I or Anaphase II

Homologous chromosomes do not separate Will result in 2 trisomy and 2 monosomy 😓

Sister chromatids do not separate Result in 2 normal, 1 trisomy, 1 monosomy ☹️

Process of analyzing the chromosomes of an individual Can help to detect aneuploidy in humans

The final image of chromosomes which have been stained, photographed and sorted into their pairs

Physical/ chemical factors that increase the rate of mutation

the overall change to the amino acid sequence

Silent mutation Missense mutation Nonsense mutation

No overall effect on amino acid sequence Mutated codon still codes for same amino acid

Affected codon now codes for a different amino acid. Substitution mutation or frameshift mutation could cause this! • Severity varies

Point missense mutations Less serious - only 1 amino acid changed Frameshift missense mutations More serious - many amino acids changed