Transport Proteins on Strike Essay

Newsflash! Transport Proteins on Strike!

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1. What is the meaning behind the PHOSPHOLIPIDS’ chant?

Phospholipids make up most of the cell membrane, in a phospholipid bilayer. Phospholipid molecules form two layers, with the hydrophilic (water loving) head facing the extracellular fluid and the cytosol (intracellular) fluid, and the hydrophobic (not water loving) tails facing one another. The cell membrane is constructed in such a way that it is semipermeable, and allows oxygen, CO2 and lipid soluble molecules through easily, while other molecules like glucose, amino acids, water, and ions cannot pass through quite as easily.

"That is the meaning behind the chant some things can pass, others cannot!”.

2. Why is H2O concerned about the aquaporin shutting down? What are aquaporins and how are they involved in plasma membrane transport? In addition to the use of aquaporins, what is another way H2O can cross the plasma membrane? Is this second way sufficient? Explain your answer.

Since aquaporins are water channels which contain transport proteins that allow facilitated diffusion of water across the cell membrane, H20 is concerned it won’t be able to get across if those transport proteins are on strike.

H2O crosses the plasma membrane via osmosis – also known as the diffusion of water across a cell membrane, and aquaporins are the main route for water entering and exiting the cell. Osmosis moves water in the direction of higher solute concentrations, (thus trying to dilute the solute). Professor Tosol went onto explain that water can also pass directly through the phospholipids as they shift around due to the fluidic nature of the bilayer. This direct diffusion isn’t as efficient, or sufficient, as the use of aquaporins.

3. Both GLUCOSE and AMINO ACID claim to have a special relationship with their respective transport proteins. What is the basis for their claims?

The transport proteins that carry those molecules across the membrane via facilitated diffusion are specific for those molecules. Glucose transport proteins only carry glucose in and amino acid transport proteins only carry amino acid in.

4. Could O2 and CO2 make the same claim as GLUCOSE and AMINO ACID? Why or why not?

No. They cross the cell membrane through simple diffusion and don’t need proteins. Mary Amico Physiology 141 Section 002 Case Study: Newsflash! Transport Proteins on Strike!

5. The movement of oxygen and carbon dioxide into and out of the cell is called gas exchange. Which two body organ systems are involved in gas exchange? Which type of plasma membrane transport is used for gas exchange? Is this method best? Explain your answer.

The two body organ systems involved in gas exchange are the respiratory and cardiovascular systems. O2 and CO2 cross the cell membrane via simple diffusion. Because cells all throughout the body require oxygen and the removal of carbon dioxide, this simple method of diffusion is the best way to transport such small molecules over a large area as efficiently as possible.

The recommendation for drinking sports drinks, which contain these ionic solutes (as well as water) to prevent or treat dehydration, is so these molecules will enter the cell and help replace what was lost and maintain as much of a balance inside and outside the cell as possible. By keeping solute concentrations as even as possible, it would promote water retention in the cells.

6. In an interview with CHLOE ESTEROL, O2 says that if GLUCOSE can’t enter The Cell, then cellular respiration would be affected. Explain the connection between glucose, oxygen, and cellular respiration.

In the case study, O2 explains that cellular respiration (for the production of ATP) requires both O2 and glucose. Glucose is an energy source which combines with O2 (and produces CO2 and waste), therefore if glucose cannot get in (because it requires a transport protein), O2 cannot do its job to combine with glucose for cellular respiration to occur. Even if O2 is present, without glucose, it cannot perform this energy-producing reaction (cellular respiration). Mary Amico Physiology 141 Section 002 Case Study: Newsflash! Transport Proteins on Strike!

7. What is the sodium-potassium pump? How does it work? Which body organ system depends on the sodium-potassium pumps to function?

In the case study, PROFESSOR TOSOL explained, The sodium-potassium pump is a transport protein which requires ATP to run. It’s a type of active transport that moves sodium and potassium ions across the plasma membrane. The sodium-potassium pump works by counteracting the diffusion of sodium and potassium ions through leak (passive) channels in the cell membrane by using ATP to eject 3 sodium ions out of the cell and to bring 2 potassium ions into the cell. The rate of transport will depend on the concentration of sodium ions in the cytoplasm.

This pump maintains the resting membrane potential of the cell at -70 mV. The body organ system which depends upon the sodium-potassium pump to function is the nervous system. This pump must function in order to maintain a resting membrane potential of -70 mV for electrochemical processes to take place within the neurons. Muscular (muscle fiber) contractions are also dependent on the sodium-potassium ion pump.

8. What are transport proteins and why are they important? What would happen to The Cell if the transport proteins went on strike?

Transport proteins are proteins that bring specific substances across the cell membrane. They are important because many very important molecules which sustain life cannot use simple diffusion to get into the cell and require these transport proteins in order to get in. Waste molecules or molecules needed for extracellular functions wouldn’t be able to leave the cell without transport proteins. The cell would not be able to maintain homeostasis, leading to many physiological breakdowns in functions though out the entire body. Neurons wouldn’t function and muscle contraction wouldn’t be able to occur. The Cell(s) wouldn’t survive, leading to the demise of the organism it supported.