Neurons have long thin processes called axons, structuresspecialized for conducting signals throughout the organism’s nervous system. Some axonal processes can be as long as 2 m—for example, the axons that originate in your spinal cord and terminate in the muscles of your toes. Small membrane-enclosed vesicles carrying materials essential to axonal function move along microtubules of the cytoskeleton, from the cell body to the tips of the axons. If the average velocity of a vesicle is 1 μm/s, how long does it take a vesicle to move from a cell body in the spinal cord to the axonal tip in the toes?

Imagine a cell wants to make a protein that will end up exported outside of the plasma membrane. (Perhaps it's a neurotransmitter, like those that are being released between your brain cells at this very moment?!) Indicate the proper order of events. [Hint: many of the structures involved are part of the endomembrane system! :)] DD Exocytosis. Protein synthesis occurs at the rough endoplasmic reticulum. The Golgi apparatus processes, sorts, and tags the protein for delivery to its final destination. The protein travels by vesicle from one organelle to another inside the cell. mRNA is transcribed in the nucleus, exits to the cytosol through, and binds to a ribosome.

If a cell increases the activity of its actin severing proteins, will it lead in the short term to MORE or LESS actin polymer mass? Chose the most accurate answer. Increased severing activity will result in LESS polymer under any conditions. Increased severing activity will result in NO CHANGE in the total amount of polymer under any conditions. It simply results in a larger number of smaller filaments. Increased severing activity will result in MORE polymer under any conditions. If the concentration of free actin monomers is below the Cc for both the plus and minus ends, then MORE polymer will result. If the concentration of free actin monomers is above the Cc for both the plus and minus ends, then LESS polymer will result. If the concentration of free actin monomers is above the Cc for both the plus and minus ends, then MORE polymer will result. If the concentration of free actin monomers is below the Cc for both the plus and minus ends, then LESS polymer will result.

What process best characterizes Ca2+ movement from the cytosol (low Ca2+ concentration) into the endoplasmic reticulum (high Ca2+ concentration)? O Calcium movement is spontaneous O Calcium movement involves active transport O Calcium movement occurs by facilitated diffusion using a transporter protein O Calcium movement does not require energy O Calcium movement occurs by passive diffusion A