Transcript What is another name for a polypeptide?

Study the diagram below and be
prepared to answer the following
questions:
• What processes are represented by the 1, 2
and 3 in the diagram?
• What is another name for a polypeptide?
Get a copy of the Stemscopedia
from the cabinet and create a tree
map like the one below in your
notebook..
Read about mutation on pages 44-46
of the Stemscopedia and pages
4 & 5 if the “Student Guide”
handout and then use the terms on
the right to complete your Chromosomal Mutations
“Mutations Concept Map”
Deletion
Inversion
Duplication
Substitution Insertion
Translocation Deletion
Gene Mutations
Mutations
Translocation
Mutations
Gene Mutations
substitution
deletion
insertion
Chromosomal
Mutations
duplication
inversion
deletion
translocation
Does
the DNA
sequence ever
get messed
up?
Yes, it does. When this
happens, we call it a mutation.
Some mutations occur simply because
DNA polymerase makes a mistake, adding the
wrong nucleotide during DNA replication.
Other mutations are caused by mutagens
(MYEW tuh junz), which are chemicals
or radiation that can damage DNA.
Chemical mutagens are being studied for
possible use in treating HIV—the virus that
causes AIDS.
UV radiation from the Sun can
damage DNA.
A mutation is a change in the
nucleotide sequence of DNA. And
as you can probably
guess, a change in
DNA leads to a
change in mRNA,
which can lead to a
change in protein
synthesis.
Point mutations occur when a single
nucleotide is changed and can result in
a genetic disorder.
A substitution is a kind of point mutation
that occurs when one base is exchanged
for another.
AGT GCA CTC
AGT GGA CTC
We can think about the DNA sequence of a gene
as a sentence made up entirely of three-letter
words. In the sequence, each three-letter word is
a Codon, specifying a single amino acid in a
Protein.
Thesunwashotbuttheoldmandidnotgethissunhat
The sun was hot but the old man did not get his sun hat
This sentence represents a gene.
Each letter corresponds to a
nucleotide base, and each word
represents a codon.
Thesunwashotbuttheoldmandidnotgethissunhat
Thesunwashotbuttheoldmandidnotgethissunhat
T hes unw ash otb utt heo ldm and idn otg eth iss unh at
Th esu nwa sho tbu tth eol dma ndi dno tge thi ssu nha t
Yes, there are! On
rare occasions, a
mutation can make
an organism more
likely to survive
and reproduce.
For example, a species
of plant might produce
a chemical with a scent
that attracts pollinating
flies. A mutation in one of the plants
could make it produce a slightly
different scent—one that is even more
attractive to pollinators. This type of
mutation would be beneficial to the
plant.
Mutations can have different affects:
How bad can
one change
really be?
How many amino acids would be effected
if the mutation below occurred?
CUUGAUACA  CUUGAAACA
How bad can
one change
really be?
But what if . . .
AUGCGUCCC  UGACGUCCC
However, most
mutations don’t
have an effect on
an organism. How
can that happen?
For one thing, not all
mutations lead to a
different protein being
made. There are more
codons than there are
amino acids.
What would happen if the mRNA codon
CUC were mutated to CUG?
CGU were mutated to CGA?
ACG were mutated to ACC?
So, more than one codon can code for the
same amino acid.