I Multiple choices (2.5 points each. Note: There is only one correct choice for each question
and please use SCANTRON only for this part of the exam.)
(a) At 37C, the mutant cells all have one genome worth of DNA, meaning that
they have not replicated their DNA and therefore have not entered S
phase. Hence they could have a defect in initiation of DNA replication (a).
Assignment #1 key
digestion of foreign particles such as bacteria: lysosome
oxidative phosphorylation (respiration): mitochondrion
modification of secreted proteins: Golgi apparatus and end
Cap1 binds the plus ends of actin filaments, because it seems to slow down actin
polymerization. When an actin filament is uncapped, both its plus and minus ends
contribute to the dynamics of the actin filament. However, when
(b). Nondisjunction in one or the other meiotic division will give rise to gametes with
two sex chromosomes instead of one. Because the only source of Y chromosomes is the
father, the gametes that produce an XYY male must be
L312/2017-Assignment #4 Key
a) (3 points). To initiate an action potential, a threshold level of membrane depolarization
must be achieved to allow for the opening of voltage-gated Na channels. As an action
potential is initiated, the initial op
L312/2017-Assignment #5 -key
Strain A has protein accumulating in the ER, which means that this cell has a
mutation that blocks transport from the ER to the Golgi apparatus. This can be
caused by a defect in COPII.
Strain B has secreted protein
1. Answer: No, your friend is incorrect. He is confusing the ability to magnify with the
ability to resolve objects close to each other. The wavelength of light and numerical
aperture (NA) of the objective used limits the resolving
L312/2017-Assignment #6- Key
1. (b). Nitroglycerin treatment bypasses the requirement for acetylcholine, because
it can be directly converted to NO. Thus this treatment will lead to relaxation of
smooth muscle cells in the absence of acetylcholine.
L312-Assignment #7 key
cAMP phosphodiesterase is important for converting cAMP into 5-AMP and
thus downregulating the activity of PKA. Without cAMP phosphodiesterase,
transcription of Brainy will increase.
All the other choices will lead to inacti
L312-2017 -Assignment #3 Key
Molecule B is more likely to utilize a carrier protein. From the graph, the yeast cells
uptake of molecule B levels off when the concentration of carbon source is high; this indicates a
saturation point for the up
A is likely to cause cell-cycle arrest.
This mutation is likely to cause cell-cycle arrest in G1. Without S-Cdk
activity, the cells will not be able to enter S phase.
Constitutively active G1-Cdk is unlikely to lead to