BIOL 2021 Lecture Notes - Electrochemical Gradient, Membrane Transport, Lipid Bilayer
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Biol 2021- march 17 2009- lecture chapter 11. Chapter 11- membrane transport of small molecules and electrical properties of membranes. The lipid bilayer of cell membranes prevents the passage of most polar molecules. This allows cell to maintain concentrations of solutes in its cytosol that differ from those in the extracellular fluid and in each of the inter cellular membrane enclosed compartments (domains). Cells use specialized transmembrane proteins to transport inorganic ions and small water soluble organic molecules across the bilayer. Transmembrane transport proteins make up usually 15-30% of all membrane proteins in a cell. Small hydrophobic molecules and small uncharged polar molecules (slow rate) are able to diffuse through the membrane. Large uncharged polar molecules and ions cant diffuse through the membrane and require transport. *membrane is highly impermeable to charged molecules (ions) no matter how small they are.
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Cellular biology answer check. please check if my answers arecorrect or not.
1) The concentration of ions inside a cell is the same as theirconcentration outside of the cell. True or false? (i chose falsesince having equilibrium inside a cell is bad)
2) Membrane transport proteins...
a)...transport membrane potentials between cells |
b) | ...transport membranes from the ER to the Golgi |
c) | ...are made up of phospholipids |
d) | ...transport molecules across membranes |
i chose d
3)The electrochemical gradienttakes into account:
a) | The concentration of solutes on either side of themembrane. |
b) | The overall charge on either side of the membrane. |
c) | Both of these. |
i chose C. (although i am sure that overall charge matters, Iwasn't sure if concentration of solutes are taken account.)
4) If no energywere expended by an animal cell:
a) | Both gradients would be depleted |
b)The K+ gradient would maintain itself. |
c) | None of these |
d) | The Na+ gradient would maintain itself. |
I chose d) mainly because I think Na+ gradient exist in animalcell and not K+ gradient.
5) Which of the following is a true statement aboutactin?
a) | Once actin has polymerized, it never depolymerizes. |
b) | Actin is a transmembrane protein. |
c) | Actin can form branched networks. |
d) | Actin filaments are organized into hollow tubes. |
I chose c. can't explain why.
6)Ion channels:
a) | Form a hydrophobic channel through the membrane |
b) | Have filters that let sugars through |
c) | Are selective for particular ions (only the |