Integrated Science 3 Honors



Simulating Protein Synthesis 01/04

Integrated Science 4 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 |Trait |Amino Acid Sequence |Trait |

|20-11-13 |hairless |20-12-13 |hairy |

|20-21-21 |plump |13-14-15 |skinny |

|16-2 |four-legged |16-6 |two-legged |

|5-7-8-1 |short nose |12-7-8-1 |long nose |

|9-4 |freckles |9-8 |no freckles |

|11-3-3 |orange skin |11-3-2 |blue skin |

|6-6-14 |female |6-6-10 |male |

Data Tables.

|Gene A |

|DNA |ACC GGT TAT |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

|Gene B |

|DNA |AGC CGA |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

|Gene C |

|DNA |TTT AAC |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

|Gene D |

|DNA |GGA CGC CGC |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

|Gene E |

|DNA |GGT AGG AAA CCC |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

|Gene F |

|DNA |ACC TAC TAC |

|mRNA | |

|tRNA | |

|amino acid sequence | |

|trait | |

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.

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