Cell membranes are composed of phospholipids. These unusual...

Cell membranes are composed of phospholipids. These unusual molecules have an area of the molecule that is hydrophobic (the "tails") and an area of the molecule that is hydrophilic (the "head"). Which would you predict about a phospholipid based on this information? Choose one: A. The tail faces the water-based cytoplasm inside the cell. B. The head faces the water-based cytoplasm inside the cell. C. The head and the tail both face the water-based cytoplasm inside the cell. D. There is no way to predict what the orientation of the head and the tail will be.

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Transcript

00:02 There, this question is asking us about a phospholipid.

00:05 And it tells us that a phospholipid has two distinct regions.

00:11 It has the head and it has a tail, which is actually two long hydrocarbon chains.

00:18 We typically draw it as two lines like that.

00:21 And we know that the head is hydrophilic, meaning it loves water.

00:35 Hydro means water, philic means loving.

00:38 So therefore it literally translates to loves water.

00:45 The tail, being those long hydrocarbon chains, they are non -polar.

00:51 So they are known as being hydrophobic.

00:54 Being non -polar, they don't mix well with water.

00:57 So we call them hydrophobic, which means water fear or water hating.

01:04 Well, literally with fear of water, that's what it translates to.

01:12 All right.

01:12 So knowing this, and this of course is the tail here.

01:16 And this, of course, is the head here.

01:20 So knowing this, it tells us we have the cytoplasm inside the cell.

01:33 And cytoplasm, the largest component of cytoplasm is water.

01:40 So cytoplasm is water -based.

01:47 And this wants to know how this phospholipid would arrange itself to this inside of the cell.

01:53 Well, since the cytoplasm is mostly water, the side of the phospholipid that is going to be attracted to it would be the head, which is hydrophilic...

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