Cell Biology Final Exam
Dr. Hoops, Fall 2008
Multiple, Multiple choice. Circle all of the correct answers. (48 pts total)
#1) Consider the response of certain chicken cells to the hormone estradiol. Which of the following
are amplification steps that happen in this process. (Note to be correct, the step must happen
during this response AND must be able to amplify the signal.)
a) The activated receptor adds phosphates to target molecules
b) The activated receptor turns on multiple G protiens
c) The activated receptor initiates transcription.
d) mRNA is translated.
2) Which of the following are true for the rhodopsin mediated signaling cascade in the vertebrate
a) Transducin absorbs a photon of light.
b) Transducin turns on a cGMP phosphodiesterase.
c) Absorbtion of a photon indirectly raises the number of open Na+ channels during this
d) Multiple signaling events reduce the level of amplification to subsequent photons.
3) The protease cascade as it occurs during apoptosis and the protein kinase cascade as it happens
in many signaling responses are similar in that:
a) There are cellular enzymes that reverse both processes.
b) They lead to amplification.
c) They contain multiple steps where the activation of one molecule is dependent on the
prior activation of another molecule.
d) They both can be triggered (indirectly or directly) from activated receptors.
4) Activated PDGF receptors turn on STAT proteins. STAT proteins enter the nucleus and turn on
transcription of certain genes. The activated receptor also modifies a GEF that activates ras.
Which of the following are illustrated by these steps? (Hint 1: You did not have to memorize
this pathway. This question is about applying what you know to additional information. Hint 2:
consider these steps only.)
d) Transformation of the signal.
5) The ability of an organism to respond to o