#Question id: 5636
#Unit 5. Developmental Biology
It appears that the oocyte and its accompanying cumulus cells secrete molecules that attract capacitated (and only capacitated) sperm toward the egg during the last stages of sperm migration. one of the chemotactic compound appears to be the
#Question id: 31217
#Unit 4. Cell Communication and Cell Signaling
#Question id: 743
#Unit 1. Molecules and their Interaction Relevant to Biology
Glycophorin, an integral membrane protein, has a single transmembrane alpha helix. Which of the following idealized hydropathy plots most likely represents the transmembrane nature of glycophorin?
#Question id: 7233
#Unit 5. Developmental Biology
Following statements are regarding to the coordination of Dictyostelium discoideum stalk and spore maturation by cAMP.
A. In prestalk cells at the slug tip, cAMP is synthesized by ACR and can either be hydrolysed by RegA or bind to PKA to trigger stalk encapsulation, which normally occurs when the tip projects upward at the onset of fruiting body formation and loses ammonia (NH3) by gaseous diffusion.
B. NH3 inhibits PKA by indirectly activating cAMP hydrolysis via DhkC-RdeA mediated phosphorylation of RegA.
C. In prespore cells, PKA activation occurs as a consequence of a signalling cascade that is activated by SDF-3, which inhibits the synthesis of GABA by prespore cells.
D. Secreted GABA then acts on prestalk cells to induce the cell-surface exposure of the serine protease domain of the ABC transporter TagC.
E. GABA also acts on prespore cells to induce secretion of AcbA, which in turn is cleaved by the TagC protease to produce the peptide SDF-2.
F. SDF-2 next activates the histidine phosphatase activity of DhkA, causing activation of cAMP hydrolysis by RegA. This allows cAMP to accumulate and activate PKA, which in turn induces spore encapsulation.
Which of the following combinations are correct?
#Question id: 3916
#Unit 3. Fundamental Processes
Transcription termination