Draw a possible hydrogen bond between a molecule of cholesterol and a molecule of water.

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All right. Hello everyone. So this question is asking us to illustrate a plausible hydrogen bond interaction between the hydroxyl group of a testosterone molecule and a water molecule. So here on the screen, we are given in advance the structure of testosterone, which only has one hydroxyl group that we'll be focusing on here. So to understand this question, it's important to understand the principle of why a hydrogen bond forms in the first place. So to summarize right, a hydrogen bond is a type of interaction that takes place between a hydrogen bond or excuse me, hydrogen atom attaching to an electron atom with a different electron atom. So to illustrate this point, let's start with a generic hydroxy group. So let's focus on this oh bond right here, recall that oxygen and hydrogen have different electron negativity values. And because of that, there's an unequal sharing of electrons in the covalent bond between them because oxygen is more electron, those electrons of the covalent bond gravitate more to oxygen, they are more attracted to oxygen. This gives oxygen a partial negative charge. Now, by contrast, because electrons are moving away from the hydrogen, at least relative to oxygen hydrogen now has a partial positive chart. So because the h has this partial positive charge, it can then interact with other electron atoms that would have a partial negative charge. So now let's bring in a water molecule. So in our water molecule, the same principles apply right, oxygen being the most electron atom here would have a partial negative charge, whereas both H atoms have partial positive charges. And so this means that two different interactions can take place and still be considered hydrogen bonds. So the first possibility is that the oxygen of the hydroxy group interacts with a hydrogen of the water molecule. The other possibility is that the hydrogen of the hydroxy group interacts with the oxygen of the water molecule. So this means that both possibilities are true. So now let's illustrate them. And I do want to very quickly mention that I will be abbreviating the structure of testosterone by using the letter R. So here we have our and our oxygen. So our first interaction that we're illustrating here can be between the hydroxy hydrogen and the oxygen of water. So close by we would have our water molecule, let me actually move this down further just for visibility sake. So here, as mentioned before, right, our hydroxy hydrogen has a positive charge which is going to gravitate towards the partial negative charge of the oxygen of the water molecule resulting in an interaction between those two. Now our other possibility involves the oxygen of the hydroxy group. And because oxygen has a partial negative charge, it's going to gravitate towards the hydrogen atoms of our water molecule, which has a partial positive. And so there you have it right, because both of these interactions are possible, our correct answer is going to be both A and B and there you have it. So with that being said, thank you so very much for watching and I hope you found this helpful.

Draw a possible hydrogen bond between a molecule of cholesterol and a molecule of water.

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Key Concepts

Hydrogen Bonding

Cholesterol Structure

Polarity of Water