Download mRNA Codon

DNA and Protein Synthesis
Proteins are vital to living organisms. They are involved in chemical reactions, oxygen
transport, muscle contraction, sensory perception, blood clotting, and many other activities. The
great variety of roles requires equal variety in the structure of protein molecules. This variety is
achieved by means of 20 different amino acids linked end to end in polypeptide chains. The
sequence of amino acids in a polypeptide chain determines the structure and biological role of a
particular protein. This sequence is determined by two nucleic acids: DNA and RNA. Both of
these molecules contain the “blue prints” for building proteins. In this lab, you will use these
blue prints to build your own “proteins”.
Procedure:
Part A
A. Obtain a cup of beads from the side counter and three of the lacing strings. The beads
represent the amino acids, the string represents the peptide bonds that holds the amino
acids together.
B. Transcribe the DNA sequence into mRNA.
C. Using the codon chart provided, translate the mRNA codons into a polypeptide chain.
Find the correct color of bead and string them together. * NOTE* Make sure you do not
start the process of translation until you reach a “Start” codon and stop at a “stop” codon.
D. When you finish, come up the front and check your polypeptide (bead sequence) with the
original to check for accuracy.
DNA Sequence:
CCAGGTATACCCGGCTTGACTAGGGGTCGCGAATACGACTAGGC
mRNA Sequence: Circle codons starting at the “Start” codon and stop and the “Stop” codon.
Amino Acid Color Sequence:
Part B: Substitution Mutation
A. You will now observe how a change in the sequence of a single DNA nucleotide
affects protein synthesis. The DNA strand is the same as in Part A, except for a
single substitution. Identify the substitution mutation and circle it.
B. Transcribe the DNA sequence into mRNA.
C. Using the codon chart provided, translate the mRNA codons into a polypeptide chain.
Find the correct color of bead and string them together. * NOTE* Make sure you do
not start the process of translation until you reach a “Start” codon and stop at a “stop”
codon.
DNA Sequence:
CCAGGTATACCCGGCTTGATTAGGGGTCGCGAATACGACTAGGCT
mRNA Sequence: Circle codons starting at the “Start” codon and stop and the “Stop” codon.
Amino Acid Color Sequence:
Part C: Frameshift Mutation
A. You will now observe how a change in the sequence of a single DNA nucleotide
affects protein synthesis. The DNA strand is the same as in Part A, except for a
single Insertion of a nucleotide. Identify the insertion mutation and circle it.
B. Transcribe the DNA sequence into mRNA.
C. Using the codon chart provided, translate the mRNA codons into a polypeptide chain.
Find the correct color of bead and string them together. * NOTE* Make sure you do
not start the process of translation until you reach a “Start” codon and stop at a “stop”
codon.
DNA Sequence:
CCAGGTATACCCCGGCTTGACTAGGGGTCGCGAATACGACTAGGCT
mRNA Sequence: Circle codons starting at the “Start” codon and stop and the “Stop” codon.
Amino Acid Color Sequence:
A
Yellow
Yellow
Yellow
Yellow
Light Blue
Light Blue
Light Blue
Light Blue
Green
Green
Green
Green
Dark Blue
Dark Blue
Dark Blue
Dark Blue
A
G
U
C
G
Orange
Orange
Orange
Orange
Red
Red
Red
Red
Yellow
Yellow
Pink
Pink
Purple
Purple
Purple
Purple
A
G
U
C
Red
Red
Red
Red
Light Blue
Light Blue
Light Blue
Light Blue
A
G
U
C
A
G
U
C
Stop Codon Stop Codon
Stop Codon
Green
U
Pink
Green
Pink
Green
C
Dark Blue
Dark Blue
Dark Blue
Dark Blue
Purple
Purple
Purple
Purple
Pink
Pink
Yellow
Yellow
Orange
Orange
Orange
Orange
A
G
U
C
Third Base in Code Word
First Base in Code Word
mRNA Codon
Second Base in Code Word
BE CAREFUL your message only starts with the translation at the START codon and you stop
with the “stop” codon. Also remember to watch the direction of the DNA.
Start codon = AUG
Stop codons =UAA, UAG, UGA
Analysis and Conclusions:
1.
Which part of the simulation represented a polypeptide?
2.
Which part of the simulation represented an amino acid?
3.
What is a peptide bond, and how is it shown in the simulation?
4.
What was the affect of the substitution mutation on the polypeptide chain?
5.
What was the affect of the frameshift mutation on the polypeptide chain?
6.
What is the process of transcription?
7.
What is the process of translation?
8.
What enzyme is responsible for transcription?
9.
What is the job of a ribosome?
10. What is the job of tRNA?
11. Which part of this simulation would occur in the nucleus of a cell?
12. Which part of this simulation would occur in the cytoplasm of a cell?
13. Frameshift mutations are generally deemed as more harmful as substitution mutations. Why?
14. How is it possible for a substitution mutation to happen, but would have no effect on the amino acid sequence?