Transcript Mutations: Changing DNA

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 Chromosomal
Large 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