DNA Damage

Types of Mutations

Silent

Missense

Nonsense

Frameshift

No change

AA substitution

Stop codon

Shift reading frame

Chemical Agents

Base analogs

Hydroxylating agents

Alkylating agents

Deaminating agents

Intercalating agents

Replace a base

Add -OH, C pairs w A

Add methyl/ethyl, G pairs w T

Remove amine group

Frameshift mutation

Proflavin

Nitrous acid

Ethylmethane sulfonate

Hydroxylamine

5 Bromo-uracil

DNA Damage

Depurination

Deamination

DNA break

Thymine dimer

Oxidation

Remove amino group, C changes to U

X ray damage sugar phosphate backbone, smaller pieces ligate back together incorrectly

UV rays cause adjacent Ts to form dimers

Form free radicals

Hydrolysis of A/G leaves unspecified base

DNA Repair

Base excision repair

Nucleotide excision repair

DNA Glyclosylase removes base. AP endonuclease & Phosphodiesterase remove sugar-P backbone. DNA Pol & Ligase add correct base

Endonuclease cuts segment with dimer. DNA Pol & Ligase

Chromosomal Mutations

Down Syndrome: Trisomy 21

Klinefelters Syndrome-XY

Turners Syndrome-XO

Diseases

Monogenetic Dz

Multifactorial

Chromosome

Mutation in single gene

Sickle Cell, CF, polycystic kidney, Tay-Sachs

Combo of small variations in genes & environmental factors

Obesity, diabetes, cancer

Excess/deficiency of genes on chromosomes, or structural changes

Trisomy 21