Cholesterol is transported in the bloodstream in lipoprotein particles. There ar

Question

Cholesterol is transported in the bloodstream in lipoprotein particles. There are several classes of lipoprotein particles, but one of the most important classes is called Low-density lipoproteins (LDL). LDL particles are composed of a single molecule of a large protein called apolipoprotein, as well as thousands of cholesterols molecules and phospholipids. Part of the apolipoprotein forms the surface of the particles and faces the aqueous phase, while other parts face the hydrophobic interior of the particle where they interact with cholesterol and the hydrophobic tails of the phospholipids. When cells need additional cholesterol, they produce a receptor protein on the surface of their plasma membrane that binds to the apolipoprotein and initiates the uptake of LDL particles into the cell via a process called endocytosis.

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

a. Cholesterol in LDL particles easily inserts into lipid bilayers

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 LDL particles?

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 as well 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 apolipoprotein belongs 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 be most 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 increased uptake of LDL particles by cells?

a. increased glycolipid synthesis

b. increased plasma membrane growth

c. increased protein secretion

d. increase protein synthesis

Explanation / Answer

i choose that 1)A 2)B 3)C 4)A 5)D

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