Exam 3 Review
Supplemental Instruction
Iowa State University / Leader: / Jacob
Course: / BIOL/GEN 313
Instructor: / Dr. Rodermel
Date: / 10/25/16

This review is meant to be a study guide that covers the bulk of the material for the exam. The questions are not written as test questions.

Test will cover lectures 17-26 (Chapter 11.1-11.3; and Chapter 12.1+12.2) and all assigned problems (DO THESE)

  1. What are the 11 characteristics of the genetic code?
  1. Genetic code has __ letters
  2. Genetic code is a ______code: each amino acid is encoded by a sequence of 3 consecutive nucleotides in the mRNA called a ______.
  3. The codon table has ______codons
  4. The code is ______(64 codons, but only ______amino acids): an amino acid can be specified by more than one codon
  5. The code has 3 types of codons: (name them and how many of each)
  1. ______codons are codons that specify the same amino acid
  2. The code is ______: codons are read as successive groups of 3 nucleotides
  3. ______sets the reading frame, hence the first amino acid of a protein (at the ___ terminus). This codon is ______
  4. What molecule serves as an adaptor molecule between mRNA and the ribosome?

Base pairing between the anticodon of the molecule and the codon is ______and ______

______have different sequences but all form a ______structure with ___ arms

Define the two important arms to know:

Acceptor arm-

Anticodon arm-

There are ~40 different tRNAs, this means that different tRNAs can accept the same amino acid. These are called ______

  1. What “solves” the problem that there are 20 amino acids and 61 sense codons but only `40 different tRNAs? ______

______predicts that some tRNAs recognize more than one codon

What causes this? (be very specific!)

  1. The code is ______. What does this mean?
  1. Define translation.
  2. What direction does the ribosome move on the mRNA? What direction is protein synthesized?
  1. What subunits does the ribosome of prokaryotes have? Eukaryotes?
  1. Where is the ribosome assembled in eukaryotes?

Translation: 4 stages

  1. Describe how tRNA charging works.
  1. Describe how prokaryotic initiation occurs (include mRNA, Shine-Dalgarno, 30S and 50S subunits, Initiation factors, fMet-tRNAfMet, GTP)
  1. There were 3 major differences between prokaryotic and eukaryotic initiation. (hint: involve initiation codon, binding sequence, and ribosomal subunits)
  1. What is the closed loop configuration in Eukaryotes?
  1. Where does the ribosome bind on prokaryotes? Eukaryotes?
  1. Describe the process of elongation in prokaryotes. (Include ribosome and 3 tRNA binding sites: peptidyl, aminoacyl, and exit, 3 elongation factors: EF-Tu, EF-Ts, EF-G, GTP, Charged tRNAs)
  1. What catalyzes the peptide bond?
  1. Where does the energy for movement of ribosome come from?
  1. What type of interaction holds together the tRNA and mRNA?
  1. Describe the process of translation in prokaryotes (include termination codons, Release factors:RF1, RF2, RF3, GTP)

Know 6 similarities/differences between translation in prokaryotes and eukaryotes. Page 301 of your book will help with this

  1. What are 3 common posttranslational modifications?
  1. What is an antibiotic?
  1. Why is translation a good target for antibiotics?
  1. What are the mechanisms of action of the following:?





  1. What are the 5 levels of gene regulation?
  1. What is the purpose of gene regulation?
  1. Match the type of gene to its function:

Structural genesA. expressed continuously; they code for essential functions that keep all cells alive

Regulatory genesB. code for proteins that function in metabolism or cell structure

Constitutive genesC. code for proteins that control expression of the structural genes at the transcriptional level

  1. Where is the operator on mRNA?
  1. Define the following:
  1. Operon
  1. Operator
  1. Regulator gene
  1. Regulatory protein
  1. Negative control
  1. Positive control
  1. Inducible operon
  1. Repressible operon
  1. The lac operon is an example of what kind of operon?

26. lac operon

a. what are the structural genes and what do they encode for?

b. What does lacO do?

c. What does lacI do?

d. What would be the result of a (lacOC/LacO+) partial diploid? LacOCis a mutation in the operator that results in the operator being unable to bind a repressor. Is this mutation cis or trans?


Review vocab terms in lecture 25/26 that weren’t covered in here for sake of space. SI session on 10/27 at 5:10 will be doing jeopardy where the focus is on vocab