Going Through the Motions: Transcription and Translation in Action Due Date: _________________________________ You will need: a) A dark colored bristol board (only front is to be used) b) Clear tape c) Highlighters (at least 3 colours) TERMINOLOGY: Define the following terms a) Upstream b) Downstream TRANSCRIPTION: Where to Start? Initiation 1. Cut out and build your double stranded DNA by attaching the bottom of segment 1 to the top of segment 2 and so on. 2. Look at your double stranded DNA and label the orientation of your two strands. a. Now to find where your gene starts. Based on what you learned in class, what nucleotide sequence(s) are you looking for? HIGHLIGHT these in YELLOW on your DNA template strand. Research 3. There are at other sequences, in addition to the initiation sequence, that are located in the promoter region. a. List the other sequence you would find in the DNA in prokaryotes, and identify where they are located specifically. b. List the other sequence(s) you would find in the DNA in eukaryotes, and identify where they are located specifically. 4. Determine the template strand. Label this as your template strand by putting RED STARS at the 3’ and 5’ ends. 5. Cut down the middle of the double stranded DNA to model the unzipping of DNA by the enzyme called: _____________________________________. 6. Set aside the non-template strand; Some of you may want to keep it just in case, if you make a mistake….. Do not lose your strands! You will need to put it back on the board AS YOU FOUND IT ORIGINALLY Elongation 8. Build your primary mRNA by using the RNA nucleotides. Then label the orientation of your mRNA. Hint: start transcription right after the 1st initiation sequence. What is the additional “beginning” section called? Hint: after you find your stop sequence, continue transcribing until the end of the DNA template What is this “end” section called? Termination 9. There are 3 possible nucleotide sequences on the mRNA which help with termination. List these sequences and then indicate what these sequences look like on the DNA template strand in your booklet. Include orientation. a. Find YOUR termination sequence HIGHLIGHT your termination sequence in PINK. POST-TRANSCRIPTIONAL MODIFICATION … 1) There are three types of post-transcription modifications that occur in eukaryotes that you learned in class. Research Research and determine if these are the same in prokaryotes. If so, describe the purpose of each of the post-transciptional modifications. Identify and label these modification pieces on your Bristol board and keep them for handing in. If not, write N/A. a. Cleaving and Splicing introns b. 3’ processing c. 5’ processing Now modify your mRNA appropriately based on your DNA by following the next steps: Research 2) SPLICING and CLEAVING a. What is another name for the 5’ splice junction? b. What does this sequence for the 5’splice junction always start with? c. What is the purpose of the 5’splice junction? d. What is another name for the 3’ splice junction? e. What does this sequence always have and end with? f. What is the purpose of the 3’ splice junction? g. Find our intron(s) by identifying the 5’splice junction and the 3’splice junction and attaching the subunits in this order: i. First attach U1 ii. Then attach U2AF iii. Then attach U2 (which should attach to the U2AF) iv. Your intron is found in between the subunits. h. To splice, you will need to complete the formation of the spliceosome by attaching U1 and U2 together. i. Now tape U1 and U2 so that they fit with this unit. ii. Now you can cut / detach the intron from the rest of the mRNA. 3) Attach the 5’cap and 3’ poly A tail. 4) Looking at your MATURE mRNA, going from 5’ to 3’, list all the different components that you encounter in your mRNA in order. Put this information in a chart. (hint: you have at least 7 components – you may include components that have been removed) TRANSLATION Initiation 1) Create your own tRNA’s by attaching them to their appropriate amino acids (make circles with 3 letter abbreciations). Use the genetic code to help you. Glue these on your board free-floating“in the cytoplasm”. Then WRITE IN the anticodon along the base of the tRNA. 2) What is the Shine-Dalgarno sequence of a mRNA? Is it prokaryotes or eukaryotes? What is it used for? If you have this, highlight in BLUE. Research 3) What is the Kozak sequence of an mRNA? Is it prokaryotes or eukaryotes? What is it used for? If you have this, highlight in BLUE. Elongation 4. Draw your final peptide chain. You may use the a.a. provided in your textbook as a guideline. Termination - You are done! What to hand in: BOOKLET of marks and answers The list of components needs to be all “secured” / glued NEATLY and LABELED on your DARK BRISTOL BOARD in their locations (nucleus or cytoplasm)