Simulating Protein Synthesis
Integrated Science 4
01/04
Name:
Per:
Background
Genes are the units that determine inherited characteristics, such as hair color and blood type. Genes are
segments of DNA molecules that determine the structure of polypeptide chains (proteins) that our cells
make. The sequence of nucleotides in DNA determines the sequence of amino acids in polypeptide chains,
and thus the structure and function of proteins.
In a process called transcription, which takes place in the nucleus of the cell, RNA polymerase reads and
copies the DNA's nucleotide sequence, creating a complementary messenger RNA (mRNA) molecule. Then
the mRNA carries this information in the form of a code to the ribosomes, where translation takes place. The
code, in DNA and mRNA, specifies the order in which the amino acids are joined together to form a
polypeptide chain. During translation, another type of RNA called transfer RNA (tRNA) is needed to bring
the amino acids to the mRNA. As the code on the mRNA strand is 'read' on a ribosome, the proper tRNAs
arrive and hand off their amino acids to the growing polypeptide chain. The process by which the
information from DNA is transferred into the language of proteins is known as protein synthesis.
In this activity, you will simulate the process of protein synthesis to determine the traits inherited by a
fictitious organism call CHNOPS. CHNOPS, whose cells contain only one chromosome, are members of the
kingdom Animalia. A CHNOPS chromosome is made up of six genes (A, B, C, D, E, and F), each
responsible for one specific protein and one specific trait.
Procedure
1. To determine the trait for Gene A of your CHNOPS, fill in the information in the box labeled Gene A in
the Data Table. Notice the sequence of nucleotides in DNA. On the line provided, write the sequence of
nucleotides of mRNA that are complementary to DNA. Then, on the line provided, write the sequence
of nucleotides of tRNA that are complementary to mRNA.
2. In order to determine the sequence of amino acids, match each mRNA codon with the specific amino
acid in Figure 1. Using a - (hyphen) to separate each amino acid number, record this information in the
appropriate place in the Data Table.
3. Using Figure 2, find the trait that matches the amino acid sequence. Record this information in the
appropriate place in the Data Table.
4. Repeat the procedure for Genes B, C, D, E, and F.
Figure 1.: mRNA codons & Amino Acids
mRNA Codon
Amino Acid # mRNA Codon
Amino Acid #
UGG
20
UUU
8
UCG
16
AAA
9
GCU
2
CCA
12
UUG
4
AUA
13
GCG
3
GGG
1
CCC
5
UAG
6
UCC
7
GAU
10
CCU
11
AUG
21
AAG
15
GGA
14
Figure 2.: Amino Acid Sequences and Traits
Amino Acid
Sequence
20-11-13
20-21-21
16-2
5-7-8-1
9-4
11-3-3
6-6-14
Trait
hairless
plump
four-legged
short nose
freckles
orange skin
female
Amino Acid
Sequence
20-12-13
13-14-15
16-6
12-7-8-1
9-8
11-3-2
6-6-10
Trait
hairy
skinny
two-legged
long nose
no freckles
blue skin
male
Data Tables.
DNA
mRNA
tRNA
amino acid sequence
trait
Gene A
ACC
GGT
TAT
Gene B
DNA
mRNA
tRNA
amino acid sequence
trait
AGC
CGA
TTT
AAC
Gene C
DNA
mRNA
tRNA
amino acid sequence
trait
DNA
mRNA
tRNA
amino acid sequence
trait
Gene D
GGA
CGC
CGC
DNA
mRNA
tRNA
amino acid sequence
trait
DNA
mRNA
tRNA
amino acid sequence
trait
Gene E
GGT AGG
Gene F
ACC
AAA
TAC
CCC
TAC
Analysis and Conclusions – Answer on a separate sheet of paper
1. Draw and color a picture of your CHNOPS organism!
2. Summarize the process of protein synthesis. Include a detailed description of what takes place during
both transcription and translation.
3. Suppose you knew the amino acid sequence of a specific protein in a cell. How would you determine
the DNA base sequence that coded for it?
4. How could one change in a DNA nucleotide alter the formation of a translated protein, and
subsequently an expressed trait? Using a protein from this lab, illustrate one example.
5. Choose one additional trait for your CHNOPS organism and add this trait to your drawing. State the
amino acid sequence, tRNA anticodon, mRNA codon, and DNA sequence responsible for this new trait.