CHNOPS
A Model of Protein Synthesis
PRE-LAB DISCUSSION
Genes are the biological units that determine inherited characteristics, such as hair color and blood type. Genes are short segments of DNA that have the instructions for making the proteins that our cells need to make. The sequence of nucleotides in DNA determines the sequence of amino acids in proteins.
In a process called transcription, which takes place in the nucleus of the cell, messenger RNA (mRNA) reads and copies the DNA’s nucleotide sequence into the form of a complementary RNA molecule. Then the mRNA carries this code out to the ribosomes, where proteins are synthesized (assembled). The code, DNA or mRNA, specifies the order in which the amino acids are joined together. The code words, or codons, in mRNA, however, are not directly recognized by the corresponding amino acids. Another type of RNA called transfer RNA (tRNA) is needed to match the mRNA codons and amino acids together. As the code carried by mRNA is “read” on a ribosome, the proper tRNA’s arrive in turn and provide the correct amino acids to the growing amino acid chain. The process by which the information from mRNA is transferred into the language of proteins is known as translation.
In this investigation, you will simulate the process of protein synthesis and thereby determine the traits inherited by fictitious organisms called CHNOPS. CHNOPS, whose cells contain only one chromosome, are members of the kingdom Animalia. A CHNOPS chromosome is made up of only six genes (A, B, C, D, E, and F), each of which is responsible for one certain 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. First, simulate transcription by using the DNA sequence to write a complementary sequence of mRNA. Then, simulate translation by using the charts provided to translate the mRNA codon into an amino acid sequence.
2. Using the charts provided, find the trait that matches the amino acid sequence for Gene A. Record this information in the appropriate place in the Data Table.
3. Repeat steps 1 and 2 for the remaining genes (B through F)
4. Using all the inherited traits, sketch your CHNOPS in the space provided below the Data Table – in color.
5. Finally, answer the questions provided.
UGG / Tryptophan
UCG / Serine
GCU / Alanine
UUG / Leucine
AUU / Isoleucine
CCC / Proline
UGU / Cysteine
UUU / Phenylalanine
AAA / Lysine
AAC / Asparagine
AGA / Arginine
GGG / Glycine
CAC / Histidine
GAU / Aspartic Acid
GAG / Glutamic Acid
Amino Acid Sequence / Trait
Tryp-GluA-Arg / Hairless
Tryp-Asp-Arg / Hairy
Tryp-Iso-Pro / Plump
Arg-Iso-Leu / Skinny
Ser-Ala / Four-legged
Asp-Cys-Phe-Gly / Long nose
Pro-Cys-Phe-Gly / Short nose
Lys-Phe / No freckles
Lys-Leu / Freckles
GluA-AspA-Ala / Blue skin
GluA-AspA-AspA / Orange skin
His-His-AspA / Male
His-His-Thr / Female
Gene A / Gene B / Gene C
DNA ACC TTG TCT
mRNA ______
Amino acid
Sequence ______
Trait ______/ DNA AGC CGA
mRNA ______
Amino acid
Sequence ______
Trait ______/ DNA TTT AAC
mRNA ______
Amino acid
Sequence ______
Trait ______
Gene D / Gene E / Gene F
DNA CTC CTA CGA
mRNA ______
Amino acid
Sequence ______
Trait ______/ DNA GGG ACA AAA CCC
mRNA ______
Amino acid
Sequence ______
Trait ______/ DNA GTG GTG CTA
mRNA ______
Amino acid
Sequence ______
Trait ______
Sketch your CHNOPS here (in color!):
Analysis and Conclusions:
1. Where are an organism’s genes found? On what cellular structures?
2. Name and very briefly describe the two steps necessary for protein synthesis.
a.
b.
3. What kind of molecule results from the process of transcription?
4. Where in the cell does transcription take place?
5. Where in the cell does translation take place?
6. What kind of molecule results from the process of translation?
7. What are the structural differences between DNA and RNA?
8. What is the advantage of making an RNA copy of the genetic information contained in DNA?
9. What is a codon? What does it represent?
10. Are there any codons that do not code for an amino acid? Which ones and what do they code for?
11. List all the codons that code for the amino acid Leucine
12. What does it mean that the genetic code is “universal”?
13. You have a segment of a DNA molecule with the following bases: TAC GTA AAC CGT
a. What is the order of bases on the complementary strand of mRNA?
b. What is the sequence of amino acids that would result from this molecule?
14. How might one change in a DNA nucleotide change the formation of the protein? What is this change called?