Download Constructing a Model of Protein Synthesis

CHNOPS
A Model of Protein Synthesis
Honors Biology
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.
mRNA
UGG
UCG
GCU
UUG
AUU
CCC
UGU
UUU
AAA
AAC
AGA
GGG
CAC
GAU
GAG
Amino Acid
Tryptophan
Serine
Alanine
Leucine
Isoleucine
Proline
Cysteine
Phenylalanine
Lysine
Asparagine
Arginine
Glycine
Histidine
Aspartic Acid
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
DNA ACC TTG TCT
mRNA ___________
Amino acid
Sequence __________
Trait ______________
Gene B
DNA AGC CGA
mRNA ________
Amino acid
Sequence __________
Trait ______________
Gene C
DNA TTT AAC
mRNA _______
Amino acid
Sequence __________
Trait ______________
Gene D
DNA CTC CTA CGA
mRNA ____________
Amino acid
Sequence __________
Trait ______________
Gene E
DNA GGG ACA AAA CCC
mRNA ________________
Amino acid
Sequence __________
Trait ______________
Gene F
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. What enzymes are involved in transcription?
6. What are introns and what are exons?
7. Where in the cell does translation take place?
8. What kind of molecule results from the process of translation?
9. Explain why DNA can be referred to as the blueprint (or instructions) for proteins.
10. What are the structural differences between DNA and RNA?
11. What is the advantage of making an RNA copy of the genetic information contained
in DNA?
12. What is a codon? What does it represent?
13. Are there any codons that do not code for an amino acid? Which ones and what do
they code for?
14. List all the codons that code for the amino acid Leucine
15. What does it mean that the genetic code is “universal”?
16. 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?
17. How might one change in a DNA nucleotide change the formation of the protein?
What is this change called?
18. How would the deletion or addition of a single nucleotide change the resulting
protein?