Biology 1202B Lecture Notes - Lecture 2: Aquaporin, Facilitated Diffusion, Phagocytosis

27 views2 pages

ochrebee715

30 Apr 2012

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Cell membranes all cells have them: the proteins in the plasma membrane may provide a variety of major cell functions. For example: transport, enzymic activity, cell-cell recognition, intercellular joining. Freeze-fracture method freeze cells and hit them with a chisel near the middle to study them. Singer and g. nicolson (1972) made a model that proposed the membrane proteins are dispersed and individually inserted into the phospholipid bilayer: this model was called the fluid mosaic model. The hydrophilic regions of proteins and phospholipids are in maximum contact with water and the hydrophobic regions are in a nonaqueous environment. These lateral movements are rapid: fluidity is influenced by temperature and by its contents. Cold membranes switch from fluid to solid state (phospholipids more closely packed) Membranes rich in unsaturated fatty acids are more fluid than saturated: amount of cholesterol may vary on the membrane. Plasma one cholesterol per phospholipid molecules. Other membranes (like those around bacteria) have no cholesterol: membranes are approx.

Related Questions

22- 25

22. As the temperature in a cellular membrane cools, the membrane
a. switches from a fluid state to a solid state
b. switches froma solid state to a liquid state
c. remains fluid if it has many phospholipids
d. A and C
e. B and C

23. How does cholestrol affect affect membranes?
a. it restrains the movement of phospholipids at warm temepratures
b. it maintains membrane fluidity by preventing high packing
c. it provides a bridge for molecules of pass into the cell
d. A and B
e. All of the above

24. An amphipathic protein
a. has hydrophilic regions
b. has regions that protude outside of the membrane
c. resides in the bilayer
d. B and C
E. All of the above

25.The major electrogenic pump for animals is
a. The sodium-potassium pump
b. The proton-Pump

Cholesterol is transported in the bloodstream in lipoproteinparticles. There are several classes of lipoprotein particles, butone of the most important classes is called Low-densitylipoproteins (LDL). LDL particles are composed of a single moleculeof a large protein called apolipoprotein, as well as thousands ofcholesterols molecules and phospholipids. Part of theapolipoprotein forms the surface of the particles and faces theaqueous phase, while other parts face the hydrophobic interior ofthe particle where they interact with cholesterol and thehydrophobic tails of the phospholipids. When cells need additionalcholesterol, they produce a receptor protein on the surface oftheir plasma membrane that binds to the apolipoprotein andinitiates the uptake of LDL particles into the cell via a processcalled endocytosis.

1. What is the likely reason that LDL particles are used totransport cholesterol in the blood stream?

a. Cholesterol in LDL particles easily inserts into lipidbilayers

b. Cholesterol id largely insoluble in aqueous solutions

c. Cholesterol is synthesized within LDL particles

d. LDL particles can form lipid rafts in the lipid bilayer

2. What is the most likely location of phospholipids in LDLparticles?

a. Bound to the hydrophilic domain of apolipoprotein

b. In the lipid bilayer that surrounds LDL particles

c. On the surface interacting with the aqueous environment aswell as interacting with the hydrophobic core of the particle

d. Within the hydrophobic core of the particle

3. What best describes the class of protein that apolipoproteinbelongs to?

a. Amphipathic proteins

b. Cell surface proteins

c. Membrane associated protein

d. Multipass membrane proteins

4. What kind of molecule on the surface of the cell would bemost likely to serve as a receptor for LDL particles?

a. a cholesterol binding protein

b. a glycolipid

c. a phospholipid

d. trans membrane protein

5. What conditions would be most likely to trigger increaseduptake of LDL particles by cells?

a. increased glycolipid synthesis

b. increased plasma membrane growth

c. increased protein secretion

d. increase protein synthesis

What is the relationship of:

- glycerol and phospholipids

- heads and tail cartoon and membrane phospholipids

- condensation reactions and synthesis of membrane phospholipids

- membrane fluidity and cell function

- length of fatty acid chains in phospholipids and membrane fluidity

- saturation of fatty acid chains in phospholipids and membrane fluidity

- amphipathic nature of cholesterol and its ability to interact with membrane phospholipids

- lipid rafts and membrane fluidity

- ether linkages in phospholipids and response to acidic conditions

- ester linkages in phospholipids and response to acidic conditions

- strong detergent such as SDS and membrane proteins

- weak detergent such as Triton X-100 and membrane proteins

- detergents and their effect on lipid bilayers

ivoryrabbit483

Biology 1202B Lecture Notes - Lecture 2: Aquaporin, Facilitated Diffusion, Phagocytosis

Document Summary

Get access

Related Documents

Biology 1202B Lecture Notes - Lecture 2: Unsaturated Hydrocarbon, Fluid Mosaic Model, Alkane

Biology 1202B Lecture Notes - Fluid Mosaic Model, Lipid Bilayer, Unsaturated Hydrocarbon

Biology 1202B Study Guide - Midterm Guide: Accessory Pigment, Passive Transport, Hydrolysis

Related Questions