Transcript Mutation - Liberty Union High School District

MUTATIONS!
Is this what we mean?
Is this what we mean?
“Frog mutations are
not typically very
cute, and they’re
often correlated quite
directly to pollution.
While frogs don’t
seem to mind having a
few extra limbs here
or there, it’s more
disturbing when one
knows the source of
their discomfort and
strange formation.”
Source:
http://webecoist.com/2010/09/2
3/yellow-lobsters-winged-catshulking-whippets-and-more/
Is this what we mean?
“This large whippet is
named Wendy and she has
something called “double
muscling”, causing her to
have much higher muscle
mass than her lithe
counterparts. Included in
these photos are a few
typical whippets to use as
comparison. Wendy is
friendly and by all accounts,
happy, but if there’s ever a
hulk television show
starring dogs… we know
who to cast.”
Source:
http://webecoist.com/2010/09/23/yello
w-lobsters-winged-cats-hulkingwhippets-and-more/
Is this what we mean?
Skin Pigmentation in Humans
This first video clip answers the question of
why humans evolved different skin pigments:
http://www.youtube.com/watch?v=-1b_li5oxNU
We mean it all!
(Well, except the X-Men part)
So, are mutations good, bad,
neutral, or all of these?
Mutations!
 Mutation:
A natural process that
changes a DNA sequence. Can be
good, bad, or neutral.
Rare all-black
penguin mutation.
Mutations!
 Mutations
make every individual
unique.
 They account for all the variation
we see in human hair color, skin
color, height, shape, and
behavior.
OBSERVATION #5:
Individuals with advantageous
variations have a better chance
of
surviving than those with less
advantageous variations.
OBSERVATION #6
Survival allows reproduction
When the surviving wormeaters reproduce
what kind of beaks will their offspring
most likely have?
OBSERVATION #7:
Many variations are inherited (in other words,
offspring tend to resemble their parents).
What do you predict would happen to the #
of individuals with the advantageous
variation in the next generation?
What about the # of individuals with the
disadvantageous variations?
INFERENCE #2:
The # of individuals with
advantageous variations will
increase in each new
generation. The # with
disadvantageous traits will
decrease.
Point Mutations

Point Mutation: The
substitution of a single
nucleotide. Three kinds:
1. Point missense – causes
one amino acid to change
(can be good or bad; leads
to variation)
Sickle Cell Anemia is
caused by a point
missense mutation.
Point Mutations
2. Point nonsense – inserts a
premature stop (usually bad)
Silent Mutations
3. Silent mutation – the DNA
has a substitution
mutation, but still codes
for the same amino acid
as “normal” DNA.
 In other words, the
protein looks like no
mutation is present, but
the DNA tells otherwise.
 Frameshift
Mutation: Addition or
deletion of a single nucleotide
causes the codons to be incorrectly
grouped.
 If
this occurs near the beginning of a
gene, it prevents many codons from
coding for the proper amino acids.
Example of a point mutation…
Original:
Point Mutation:
The fat cat ate the wee rat.
The fat rat ate the wee rat.
Example of a frameshift mutation…
Original:
Frameshift:
The fat cat ate the wee rat.
The fat caa tet hew eer at.
(the “t” was deleted completely)
Other drivers of mutation
Radiation,
chemicals, and UV
radiation from the
sun can damage
thousands of
nucleotides every
day.
 Our DNA can
reverse mutations
most of the time.

DNA Repair
Only when DNA changes are in egg and
sperm cells are they passed on to the
next generation.
 Without mutation there would be no
variation, and without variation there
would be no evolution.
