Due Monday, Oct. 8
Please provide complete answers (mechanistic explanations) to the following questions. Please
answer all parts of each question.
Questions for week 2
1. What organelle is the main site of cellular energy (ATP) production? What organic
molecule do cells commonly metabolize (split/burn) to make ATP molecules? What are
the names for those processes? What inorganic molecule must be present for a cell to
produce LOTS of ATP molecules (36 or 38) from that single organic molecule? In
comparison to me (I don’t run marathons), would a marathon runner have more, less, or
an equal number of mitochondria in his leg muscle cells? Why?
Mitochondria; glucose (or short chain fatty acids); Glycolysis/cellular respiration; Oxygen;
more mitochondria because a cell will increase its mitochondrial density in response to
increased use.
2. Where, in the cell, are proteins synthesized? What are the individual building blocks
(type of organic molecule) of proteins? Where are carbohydrates and lipids synthesized?
What organelle modifies, packages and ships proteins off for further processing at the
Golgi apparatus?
At ribosomes, often attached to the Rough ER; Amino Acids; Smooth ER; Rough ER.
3. What three cytoskeletal elements provide structure for a cell? What type of organic
molecules are they made of?
Microfilaments, microtubules & intermediate filaments; all are made of protein.
4. How would a cell import a large, polar molecule into its cytoplasm if the concentration of
that molecule were much higher inside the cell than outside the cell? Tell me what
cellular-produced molecules must be involved and why?
Using active transport through a channel or a pump. This uses ATP and pumps or transport
proteins. They must be involved because the cell is moving a large, polar molecule (which could
never diffuse through the plasma membrane on its own) against its concentration gradient. It
cannot do that without the application of energy.
5. Why would a cell have cilia on its surface? Where in the body would you expect to find
cells with cilia (tell me generally and give a specific example)? Smoking damages cilia
on your cells; please speculate on what might happen due to this impaired function.
Cells that need to move particles across their surfaces would have cilia. So any place in the body
that requires this would need cilia; respiratory tract and female reproductive tract are two
examples. If cilia no longer move then mucus and trapped particles are no longer expelled, so a
person compensates by coughing which can loosen and expel mucus.
6. What is diffusion? Why does it occur? What is osmosis? What is facilitated diffusion?
Does the cell need to supply energy for diffusion to occur?
Diffusion is the movement of a solute from an area of high concentration to that of low
concentration. It occurs due to the random collisions between particles with KE. Osmosis is the
movement of water from an area of high to low concentration. Facilitated diffusion is also
passive, like diffusion, but it requires a carrier molecule as well; No energy is needed because
the solute is moving along its concentration gradient.