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MCB 229 Spring 2000 Study Guide 11 Prof. Terry
Covers Lecture for March 14

This study guide is intended for you to use while you are doing the assigned text reading. Quiz questions will be made with reference to topics in this study guide. Quiz #11, based on questions from this study guide, must be completed by midnight before the class on Tuesday, March 14. You will need to create your "myWebCT" account and visit the MCB 229 WebCT page in order to access this quiz.

Chapter 11 (p. 226-233); also Chapter 13 (p. 258-262): protein synthesis and the genetic code.
  1. Note: some of this information will be review of material you've had in Biology 107 and perhaps other MCB courses. If this material is new to you and you did not take Biology 107, you may find it profitable to review that material: go to <http://www.sp.uconn.edu/~bi107vc/fa99/terry/RNAprot.html>.
  2. What are the components required for protein synthesis?
    (a) the information for amino acid sequence is carried by: ___________________________
    (b) the "decoding machine" that allows this information to be converted into a polypeptide is: ___________________
    (c) the carrier molecules that bind amino acids and align them sequentially are: _____________
    (d) the enzymes that join item (c) with amino acids are: _______________
    (e) the energy source to join amino acids with carrier molecules: _______________
  3. Polypeptide synthesis begins at the __ end and proceeds to the ___ end of the polypeptide.
  4. The rate of polypeptide synthesis in bacteria is about ______/min, contrasted with eucaryotes at about ________/min.
  5. What is a polyribosome? Is this a common or rare situation? What is meant by coupled transcription/translation? Does this process occur in prokaryotes, eukaryotes, or both?
  6. What are the distinctive properties of t-RNAs? How many different types of t-RNAs are there in a bacterial cell (see p. 258)?
  7. What components are found in a 30S ribosomal subunit?________________ In a 50S subunit?________________________ Roughly how many ribosomes are present in a growing E. coli cell?__________
  8. How many sense codons are there in the genetic code? (see Table 13.1 and relevant text). Which amino acids have the highest degeneracy? Are there any "non-degenerate" codons (i.e., only one codon to specify a given amino acid). What is "wobble"?
  9. Initiation: Which end of mRNA ______ binds to which ribosomal subunit ____? What role does the Shine-Dalgarno sequence play in this process? ______________________________________ What is the first amino acid inserted in bacterial translation? ________ In eucaryotes? _____ In archaea? _______ What is the initiation codon? _____ Is it universal, or are there exceptions?_________ Are any other components required beside mRNA, ribosome, and aminoacyl-tRNA; if so, what? ___________ Examine Fig. 11.28 for details, as well as Fig. 13.6 and relevant text.
  10. Elongation: What is the function of the P-site? Of the A-site? What component is responsible for the transpeptidation enzymatic activity? Where does the energy to form this peptide bond derive from? What is the translocation phase of elongation? What happens? What is the energy source for this process? Examine Fig. 11.29 for details, as well relevant text.
  11. Termination: What are the termination codons? _______________ What happens during termination? Is there a t-RNA for termination codons? What components are required for termination? Examine Fig. 11.31 for details, as well as Fig. 13.6 and relevant text.
  12. Energetics: What is the final cost of adding each amino acid to a growing polypeptide? Consider a "typical" protein with some 500 amino acids: about how much ATP was required to synthesize this protein?
  13. Folding: How does polypeptide differ between procaryotes and eucaryotes? What is meant by "protein splicing"? What is an intein? An extein?