Three questions on various genetics topics.
1. Two mothers give birth to sons at the same time in a busy
urban hospital. The son
of couple #1 is afflicted with hemophilia A. Neither parent
has the disease. Couple #2 has a normal son despite the fact that the father
has hemophilia A. The two couples sue the hospital in court claiming that a
careless doctor swapped their babies at birth. You appear in court as an expert
witness. What do you tell the jury? Make a diagram(s) that you can submit to
the jury.
2. Meiosis results in a reassortment of maternal and
paternal chromosomes. If 2n =6 for a given organism. (a) What are the possible
numbers of different combinations of paternal and maternal chromosomes. (b) If
no crossing over occurs, what is the probability that a gamete will receive
only paternal chromosomes?
3. You are interested in using bacteria to bioremediation at
an old chemical plant and convert toxic compounds toluene and benzene into
harmless compounds. You discover bacteria that are able to tolerate high levels
of toluene and benzene, and you suspect that this is due to the ability of the
bacteria to break these compounds into less-toxic products. If this true, these
toluene- and benzene-resistant strains will be valuable for cleaning up toxic
sites. (a) How could you find out whether these bacteria are metabolizing
toluene as a source of carbon compounds? (b) Assuming that the bacteria do have
an enzymatic pathway to break down toluene, would you predict that genes
involved are constitutively expressed under positive control or under negative
control? WHY?
