Cholesterol would NOT be expected to move between membranes by: Please choose the correct answer from the following choices, and
then select the submit answer button. dissolving in the cytosol and diffusing to proteins at the target membrane. being transported as part of the membrane of vesicles. being transferred by proteins as membranes come into contact. being transported by specific carrier proteins. Actually, it would be expected to use all of these mechanisms.
Te correct answer is "Being transported by specific carrier proteins".
Explanation:
Cholesterol is one of the most important lipids in our body. It is useful for membrane formation and for sexual and suprarenal hormone synthesis. The organism obtains cholesterol from food and liver production. It goes to the blood where it is transported by lipoproteins to its final destiny.
In the intestine, cholesterol is absorbed in three phases:
<em>intraluminal phase</em>: in this phase micellar formation is necessary for cholesterol absorption. Micellar solubilization is a transport way for cholesterol to diffuse through the mucus barrier that covers intestine surface microvilli. Once there cholesterol is available for intestinal cells.
<em>mucose phase</em>: in this phase cholesterol pass from the lumen to the cytoplasm of the intestinal cells, and when necessary, from the cytoplasm to the intestinal lumen. In the cells´ membrane, there are proteins that transport cholesterol to and from the interior of the cell.
<em>Intracellular phase</em>: In the intestinal cell cholesterol is sent to the endoplasmic reticulum where it is reesterified to be transported in the blood. As cholesterol is insoluble it is packaged in lipoproteins to be transported.
Each lipoprotein has a union site that is specific for a target membrane receptor. Lipoproteins get in the target cells by endocytosis mediated by the specific receptors. Once in the interior of the cell cholesterol is taken from the lipoprotein by breaking the ester link, and then they reesterify it to include it in the membrane.
I took this when i was in 8th grade so i will try my best to tell you air moves all the time and everywhere. it moves by us breathing the air in our lungs. trees provide us by air.
