Biologia Ch.5

1. Briefly discuss the differences between a phospholipid and a lipid? (Hint: structurally and functionally)
Lipids do not dissolve in water but are soluble in alcohol, ether, or other organic solvents.
Phospholipids are important because they DO HAVE water soluble glycerol heads enabling many of them to form a poly-molecular structure that we call a membrane, which limit the passage ofwater and water-soluble compounds through a cell membrane, enabling the cell to keep its contents separate from the outside environment.
2. Briefly discuss how the development of electron microscopy revolutionized cell biology?
In normal microscope will see up to nucleus, mitosis, meiosis. But through electron microscope the spindle fibers, DNA, which lead us to know more about the real matterof the cell(life)..in electron microscope. It changed the cell biology to know more about the functional aspects of nucleus and chromosomal arrangement and also number of chromosomes, hybridization, crossing over, it enhanced the researchers to take fast track
3. A cell membrane is a very fragile structure. However, in its natural setting (human body) it is maintained for the life of thecell. Briefly discuss how a phospholipid is held together.
The phospholipids are held together by only by weak hydrogen bonds of the heads and the even weaker interactions between the hydrophobic lipid molecules in the tails.
4. Discuss the role of temperature in maintaining a balance between saturated and unsaturated fatty acids in membranes. (Hint: what happens when temperatures decrease orincrease)
In lower growth temperatures, biological membranes tend to increase in their unsaturated fatty acids content, while at higher temperatures, saturated fatty acids are more abundant (home viscous adaptation).
5. Another way to maintain membrane fluidity is with cholesterol. Briefly discuss the role of cholesterol at moderate temperatures as well as low (cold) temperatures.
Withoutcholesterol, cell membranes would be too fluid, not firm enough, and too permeable to some molecules. In other words, it keeps the membrane from turning to mush.
While cholesterol adds firmness and integrity to the plasma membrane and prevents it from becoming overly fluid, it also helps maintain its fluidity. At the high concentrations it is found in our cell's plasma membranes (close to 50percent, molecule for molecule) cholesterol helps separate the phospholipids so that the fatty acid chains can't come together and crystallize.
Therefore, cholesterol helps prevent extremes-- whether too fluid, or too firm-- in the consistency of the cell membrane.
6. Differentiate between integral and peripheral membrane proteins. (Hint: be detailed!!!)
Peripheral proteins are under thephospholipid bilayer, while integral proteins are inscribed in the bilayer. Integral proteins pass entirely through the lipid bilayer of the plasma membrane and have domains that go from the outside of the cell to the cytoplasm inside the cell. While peripheral proteins are only on the one side of the lipid bilayer, either the outside of the cell or the cytoplasmic side inside the cell, but not both.7. Differentiate among the following: 1) chemical energy (ATP), 2) potential energy, and 3) kinetic energy.
* Potential energy is stored energy, ready to be used.
* Kinetic energy is the energy in the movement
* Chemical energy the part of the energy in a substance that can be released by a chemical reaction.

8. Differentiate between a channel and a carrier protein. Providespecific types of channel and carrier proteins.
Both are integral membrane proteins involved in moving a molecule or ion across a membrane. Both have only one or a couple specific targets, so there are many kinds for specific molecules. The difference is how they accomplish this task. Carrier proteins transport molecules by changing shape. First, a molecule on one side fits the binding site,...