Study Guide
Chapter 27
Protein Metabolism
1. Define: codon, reading frame, open reading frame, replication, transcription, translation, a degenerate
code, a wobble base, seginal sequences
2. What is the codon used to start a protein sequence? To stop a protein sequence?
3. Why is the genetic code a 3 letter code?
4. If I have a tRNA with the anticodon 3'...G-C-I...5', what possible codons on an mRNA message
could it bind to? What about 3'... AUU...5'?
5. If there are 61 possible amino acid anticodons, what don’t some organismisn have 61 different
tRNA’s?
6. Discuss the following statement. ‘In an organism there is a single DNA that can be transcribed into a
single RNA that can be translated into a single protein’
7. Describe the structure of tRNA...of a ribosome.
8. Discuss the process by which an amino acid is attached to a tRNA. What enzymes are involved?
What cofactors are needed? How much energy is used and what it the chemical form of the energy?
Is there any proofreading in this process?
9. What is the difference between class I and class II aminoacyl-tRNA synthases?
10. What are the structural clues that an aminoacyl-tRNA synthase uses to recognize its correct tRNA.
11. Describe the process of protein synthesis. Go into the details of initiation, elongation, and
termination. What enzymes are involved? What cofactors are needed? How much energy is used and
what it the chemical form of the energy? Is there any proofreading in this process? What are the
differences between prokaryotic and eukaryotic protein synthesis?
12. Describe several of the posttranslation changes that can be made in a protein.
13. What are some antibiotics or toxins that can effect the translation process and how do they work?
14. How are proteins targeted to different organelles within the cell? Does targeting occur in
prokaryotic cells?
15. How are proteins degraded in a cell?