Mutations: Changing DNA

SBI4U Biology

Mutations: Changes in the quantity or composition of DNA in a cell Changes in number or structure of chromosomes Spontaneous Induced Mutagens = UV, X Rays, other radiation; chemicals; heavy metals

Gross ChromosomalLarge scale changes to chromosomes:

Deletion = loss of an entire portion of chr. Translocation = section of a chr. breaks off & reattaches incorrectly elsewhere Inversion = section of a chr. breaks off & reattaches upside down

Aneuploidy = incorrect number of chromosomes Trisomy = extra chromosome (2n +1) Monosomy = missing chromosome (2n -1) Triploid = 3n, Tetraploid = 4n

Gross Chromosomal

Gross Chromosomal

Trisomy & Monosomy

Point Mutations:Small scale changes to DNA & genes: Point = replacing a single nucleotide, affecting a single amino acid in the polypeptide. Silent = coding changes, amino acid remains same. Missense = coding changes, new amino acid Chain termination = mutation makes a coding triplet become a STOP codon; translation stops early, protein too short. Nonsense = mutations makes a STOP codon a regular codon; translation keeps going, protein too long.

Point Mutations:

Point Mutations:

Frameshift Mutations:

Sometimes, a small change has big effects, as in these cases: Insertion Frameshift = adding an extra nucleotide; changes how you read the codons in mRNA by shifting everything one ‘letter’ over to the right Deletion Frameshift = removing a nucleotide; changes how translation happens in mRNA by shifting everything one ‘letter’ to the left.

Frameshifts:

Frameshifts:

Mutation Examples:

I LOVE HER SO MUCH I COULD MARRY HER.

Silent:I LOVE HER SO MUCH I COULD WED

HER.

Missense:I LOVE HER SO MUCH I COULD PUNCH

HER.

Mutation Examples:

I LOVE HER SO MUCH I COULD MARRY HER.

Chain Termination:I LOVE HER SO MUCH I COULD.

Nonsense:I LOVE HER SO MUCH I COULD MARY HERE

THIRST PINK UTAH MONGOOSE LABEL WINE FLIRT LAVA LAMP TOOL BARGE MAPLE NOSE

HAIR RITZ CRACKER CONSPIRACY GONG SHOPPING SPREE WIT’S END NEVADA WONDERFUL SQUID RICE KANGAROO

CELEBRATE WART…

Mutation Examples:

I LOVE HER SO MUCH I COULD MARRY HER.

Deletion Frameshift:I LOVH ERS OM UCHI C OULDM ARRYH

ER

Insertion Frameshift:I LOXV EHE RS OMUC H ICOUL DMARR

YHE R