Codons and Mutations
7th Grade – Life Science
S7L3a
Telephone
You will be given a phrase.
Whisper the phrase word for word to the student right next
to you until the last student in a line receives the phrase.
The last person will write down the phrase. (Teacher select
one of the phrases below.)
"I tried bleaching my hair and it turned orange.”
"The quick brown fox jumped over a lazy dog eating a
hamburger.”
"We have contacted your Earth governments and they
refused our existence.“
“Yolanda’s aunt shared her secret sweet potato pie recipe
with me.”
You were asked to restate (or copy) a phrase word
for word from person to person.
Sometimes a task like this is done successfully.
Sometimes a task like this is done with little error
and the end statement is very similar to the original
statement.
Sometimes a task like this is done with so many
errors that the end statement is nothing like the
beginning statement and the statement changes in
meaning greatly.
When you look at a person, you see skin, eyes, hair, etc. What substance are
these features made of?
Write in notes:
When you look at a person, you are looking at proteins. Their skin, eyes, hair, etc.
When genes are being read to make proteins, the bases are read in threes.
These groups of three are referred to as CODONS.
Codons- A sequence of three nitrogen bases in a gene sequence that code for a
specific amino acid
Amino Acid- Building blocks of proteins (ie: proteins are made up of amino
acids)
*Each codon codes for one amino acid.
*Multiple amino acids code for one protein.
• For the following nucleic acids, practice
groupings the bases into codons
• ATTGCGTAC
ATT GCG TAC
• Practice - GTACCGGGTACGTAC
GTA CCG GGT ACG TAC
• Identify the nitrogen in the first nucleotide for
the third codon for both nucleic acids above.
(The correct nitrogen bases have been
highlighted in red.)
Do Now: When you hear the word
mutation, what comes to mind?
DNA is copied when new cells are
made.
Why do new cells need to be made?
• For the organism to grow
• For the repair and replacement of
old or lost cells.
Read : “What is a Gene Mutation and how do Mutations Occur?”
When DNA is being copied, an error can be made in the arrangement of the base pairs.
A mutation is a permanent change in the DNA sequence of a gene.
There are different types of mutations (we have read about some of them–
SANDERS
Point (substitution)
SNNDERS
Deletion
S_ _DERS
Insertion
SANANDERS
Can mutations be harmful?
Are mutations always harmful?
•
•
•
Some mutations can be harmful (such as genetic diseases).
Some mutations can have no effect at all.
And MANY mutations can be beneficial.
The Impact of Mutations
Next Step:
How exactly do mutations effect the job of the
gene?
Video- “Finding Cures is Hard”
1. What do genes produce? (In other words, genes are
recipes for making different_____________)
2. How do mutations effect the job of the gene?
3. What type of mutation is cystic fibrosis?
Extension Questions
1. Variation in a species is important because it
may give individuals within a species a
advantage for survival.
2. In a population of polar bears, some may
develop thicker fur. How?
3. The polar bears with thicker fur may have
the advantage to survive. Why?
“Genetic Variation”
1) Why are humans genetically so similar?
2) How will variation in humans become
greater?
Identify the mutation:
ATGCTA
ATGGCTA
(Duplication)
AGGCTA
AGCTTA
(Deletion and Duplication)
ATGCTAATG
ATGCTACTG
(Point Mutation)