Is serine chiral? Draw serine and identify the chiral atom. Explain why serine is chiral.

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Hi, everybody. Welcome back. Our next question says, is cysteine chiral justify your answer if it is chiral, draw its structure and identify the chiral atom. Well, first of all, we need to think about what the structure of cysteine is. If we look it up in our book, the CY R group is CH two sh So we actually need to draw the structure no matter what because to, to determine if it's chiral, it's helpful to look at the structure. So let's draw our group first. So we'll have HS which is attached to Sage two. There's our, our group that Sage two is attached to the alpha carbon, which I'm indicating with a little dot There it has the NH two and then the C which is double bonded to an O mnoh. So one way to look for whether a molecule is chiral is, does it have a Plaintiff symmetry? But in a more complex molecule, we want to look for chiral carbons. Is there a carbon at the Cairo center? If so the molecule is chiral. So we look for a chiral center which would be a Carmen atom with four different groups attached to it in a tetrahedral geometry. So can't be have a double bond, can't have a triple bond must have tetrahedral geometry. So four single bonds with four different groups around it. So first, we need to find all the carbon atoms in this molecule, I'll highlight them in blue. So first, we have the one that's in the R group for alpha carbon and then our carbon carbon. So we'll just number them 12 and three. So the R group carbon first, then the alpha carbon and then the carbon carbon. So for carbon number one, well, right away when we look at it, it has the sulfur on one side and the rest of the molecule in the other, but it only has two bonds to other carbons. It also has two hydrogen atoms bound to it. So this is not a chiral center because it doesn't have four unique groups around it. So let's move on to carbon. Number two, which is the alpha carbon. It has an NH two, it has a hydrogen, those as we recall, aren't specifically shown on a line structure. And then it has the R group of our system and then the carboxylic acid group of the amino acid. So this one is a Cairo center since it has four different things bonded to it. Now, let's look at number three. Number three has AC O double bond and therefore, does not have a tetrahedral geometry. So it's not tetrahedral. So carbon three is not a chiral center. So we have carbon two. The alpha carbon is a chiral center. And I just realized I labeled that as central center, but it's a Cairo center. Now, we look back at our question and it said is it Cairo? Since it is a chiral center. Yes. Sistine is Cairo and we drew its line structure. So again, it has HS bonded to ach two bonded to the alpha carbon which has an NH two. And then the carboxylic acid group, it is chiral and the chiral atom is the alpha carbon. See you in the next video.

Is serine chiral? Draw serine and identify the chiral atom. Explain why serine is chiral.

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Key Concepts

Chirality

Amino Acids

Chiral Center