Download 8 7 Mutations

Happy Thursday!!!
10/27/2011
Turn to your notes page
after yesterday’s sheet!
Read & do those
questions…
Quick, quick quick,
10 minutes!
Today!!
GO over mutations!
Tomorrow:
Review for test!
MONday: Test
Don’t forget…if you want some extra help
or if you’ve been absent, PLEASE come
see me tomorrow during B lunch! Grab
lunch & bring it in here!
Mutation background . . . . . . .
•Mutation = the alteration of an organism’s
DNA!!
•A malfunction during the process of meiosis
•From exposure to a physical or a chemical
agent, a mutagen.
•Can be a
•change in one base pair
•insertion OR deletion of large segments of
DNA
• But not to worry . .. . . 
• Most mutations are automatically repaired by
the organism’s enzymes and therefore have
no effect!!!
• If not, the mutation can be passed on . . . . . .
8.7 KEY CONCEPT
Mutations are changes in DNA that may or
may not affect phenotype!!!
Whoa, what’s THAT?
It’s “how something looks” or
its PHYSICAL appearance.
Don’t freak out…we’ll learn
more about this next
week…genetics! 
Some mutations affect a single gene, while
others affect an entire chromosome.
• mutation = change in an organism’s DNA.
• Many kinds of mutations can occur,
especially during replication!!!!
mutated
base
• Affects a single gene
• point mutation = substitutes
1 nucleotide for another.
• frameshift mutation inserts
or deletes a nucleotide in the
DNA sequence!!!
Remember the
READING FRAME
from Friday?
A frameshift mutation
SHIFTS the reading
FRAME! 
Affect entire chromosome,
many genes!!!
– @ Crossing over exchange of unequal
segments
– Translocation –
moving of a piece of
1 chromosome to a
nonhomologous part!!
More details on this when we
study MEIOSIS …My-Oh-Sis!
• Translocation results from the exchange of DNA
segments between nonhomologous chromosomes!!
Mutation Fun Facts!!!
• IF in a body cell, the cell with the mutation is affected, &
daughter cells (from mitosis) can be affected by the altered
DNA, but the mutation will not be passed on to your kids!!!!
○ Aging, cancer
• IF in a gamete (sperm or egg cell), the altered DNA will be
transmitted to embryo and may be passed to subsequent
generations (genetic disorders)!!!!
• ○ If the mutation affects a single gene, it is known as a gene
mutation.
– Sickle cell anemia, Tay-Sachs disease, Huntington’s disease,
cystic fibrosis, or albinism.
– More on ALL of this next week when we study GENETICS! 
• Chrom mutations tend to
have a big effect…WHY?
• Some gene mutations
change phenotype.
– may cause an “early”
stop codon
– may change protein
shape or active site.
– may change gene
regulation
Cystic Fibrosis is
caused by a deletion –
too much mucous,
no cure! 
blockage
no blockage
Some folks have a mutation that
increases cholesterol
Some gene mutations DO NOT
affect phenotype.
– may occur in a noncoding
region (you have “extra DNA” that
is never transcribed…)
– may not affect protein
folding or the active site,
so the protein may still
function normally
– SOME amino acids are
coded by several codons…
CGU
CGA
CGC
CGG
ALL FOUR
CODONS CODE
FOR WHICH
AMINO ACID??
LOOK IT UP!!
Mutations can be caused by several factors.
• Replication errors can cause
mutations.
• Mutagens, such as
– UV rays and chemicals,
cause mutations.
• Some cancer drugs use
mutagenic properties to kill
cancer cells.
For the rest of the period:
Rice Krispy DAY 1: work hard, do the paper part of
this activity today…and if you WORK STEADILY &
EFFICIENTLY!
MAKE RICE KRISPY TREATS TOMORROW!