Biology 207 - Practice Questions 3
Biochemical pathways & complementation tests
Question 1 What is the purpose of:
b) cell division
e) eukaryotes alternating between haploid and diploid
f) recombination during meiosis
g) meiotic crossovers
Question 2 Consider the experiment done by Srb and Horowitz (Lecture 5 section 3).
a) The symbol '+' is used to represent three different things. What are they?
b) Positive and negative controls are done so that we know that an experiment has worked
the way it should. Which control(s) in the table allow them to know that they didn't make the
Use a WT strain of Neurospora instead of the arg3 strain.
Use argH cells that were dead.
Use MM+citrulline media that was actually toxic.
Question 3 Students often confuse biochemical pathway analysis with complementation
tests. To illustrate the differences consider this synthesis pathway from S. cerevisiae. You
have isolated three mutant strains unable to synthesize compound “B”. The blocked step in
each mutant strain is shown. Mutations 1 and 3 are in the same gene.
Complete both tables with the expected results where + indicates growth and - indicates no
growth. Also identify positive controls and negative controls.
a) Biochemical pathway analysis results b) Complementation test results
Question 4 (This is an old midterm question.) You have isolated five Neurospora mutant
strains that are unable to synthesize an essential compound, C.