In this lab you will model the process of protein synthesis
Last updated: 2/21/2023
In this lab you will model the process of protein synthesis First you will build a model of a segment of the gene that codes for a beta globin polypeptide Then you will model the process of transcription by using your segment of DNA to build an mRNA segment Next you will model the process of translation by using your mRNA segment to build part of the beta globin polypeptide chain Finally you will model how a small change in the DNA sequence affects the synthesis process and the final shape of the hemoglobin protein Safety Follow safe practices during this investigation Materials Sticky note tabs 5 colors 3 strips of paper ribbon or string each about 2 cm x 60 cm Tape String or yarn 16 paper circles about 2 cm in diameter 10 clay balls about 4 cm in diameter Paper Pencil pen or marker Procedure and Data 28 points Part 1 Modeling Transcription 14 points You will first build a model of a segment of DNA This segment is part of the gene for beta globin a polypeptide found in normal hemoglobin You will make both complementary strands of DNA Then you will use your DNA model to make an mRNA model by transcription 1 The sequence of nitrogenous bases in the template DNA strand is CAC GTA GAC TGA GGA CTC CTC TTC This sequence is given in the table below as a series of triplets Use the rules for base pairing to determine the sequence of bases for the complementary DNA strand Record this sequence in the table Then determine the sequence of bases in the segment of mRNA that is complementary to the template DNA strand Remember that RNA contains uracil U in place of thymine T Use the table to record the sequence of mRNA codons 2 points Base Sequences of DNA and mRNA Strands table to record the sequence of mRNA codons 2 points Base Sequences of DNA and mRNA Strands Template DNA strand CAC GTA GAC TGA GGA CTC CTC TTC triplets Complementary DNA strand triplets Complementary mRNA strand codons 2 Assign a color to each of the five nitrogenous bases Record this information in the table below Then count the number of times each base occurs in the two strands of DNA and the single strand of mRNA Record the totals in the table 2 points Colors and Numbers of Model DNA and RNA Bases Nitrogenous base Assigned color Number of times base occurs Guanine G Thymine T Adenine A Cytosine C Uracil U 3 Make enough sticky note strips of each color to represent the total number of times that base occurs For example if guanine is assigned blue and occurs 10 times you should make 10 blue strips Label the non sticky side of each strip with the letter that represents the base 4 To start making your DNA model place the labeled sticky notes and two 60 cm strips of paper on a flat working surface Label one strip Template DNA strand Label the left hand end of this strip 3 and the right hand end 5 Starting at the 3 end follow the DNA sequence for the template strand given in Step 1 sticking the bases to the paper so that they hang off the bottom of the strip Leave about 0 5 cm between the bases Verify the sequence of your model template strand after it is complete 5 Label the second strip of paper Complementary DNA strand This time label the left hand end 5 and the right hand end 3 Starting at the 5 end use the DNA sequence for this strand that you determined in Step 1 This time stick the bases to the paper so that they extend off the top of the strip 6 Place the complementary strand below the template strand to model a double stranded segment of DNA that is not twisted into a double helix 7 Use a long piece of string or yarn to represent the nuclear membrane Encircle the model DNA segment 8 Draw or attach a photo of your finished model in the space below 6 points 9 Repeat Step 5 to model the process of transcription but this time label the strip of paper mRNA strand Construct the complementary strand of mRNA Think about what happens to the original DNA and where transcription occurs 10 Draw or attach a photo of your finished mRNA model in the space below Include what the DNA looks like and use the string