Transcript DNA Mutations

DNA Mutations
Section 11.3
Review
• DNA controls structure and function of
cells because it holds the code to build all
proteins.
gene
DNA
mRNA
Protein
transcription translation
trait
Mutation—mistakes in the DNA
• Mistakes can occur
randomly through
errors in replication,
transcription, or cell
division.
• External factors can
also cause mutations.
• These mistakes could
be good or bad.
• Mutations can occur in reproductive cells
(sperm or egg) or in body cells.
Mutation in
sperm or egg
Only offspring affected
New protein
that is better
than before
New protein
hurts organism
or doesn’t work
at all.
Mutation in
body cell
Only adult cells
affected
Cell may no
longer work
properly
Cell doesn’t
reproduce
properly
may lead to
cancer
Certain types of mutations are
found in the genes or DNA
• Point (substitution) mutation is the change
in a single base pair.
– EX. When you change one letter in a
sentence:
• THE DOG BIT THE CAT.
• THE DOG BIT THE CAR.
DNA mutations con’t
• Frameshift mutation is when one base is
deleted or inserted and the whole
sequence shifts.
– EX: If you delete the letter G, from the original
sentence:
• THE DOG BIT THE CAT.
• THE DOB ITT HEC AT.
– EX: If you insert the letter A, into the
sequence.
• THE DOG ABI TTH ECA T.
Mutation causes are called
mutagens.
• Radiation (nuclear, x-ray,
UV, etc), asbestos,
formaldehyde all can lead
to mutations.
• Organisms have evolved
several enzymes that
check and repair DNA,
but the more exposure to
a substance, the more
chances for mistakes.