Welcome Guest Search | Active Topics |

Tag as favorite
Polarity
Options
Previous Topic Next Topic
Nicole_5521
#1 Posted : Thursday, June 03, 2021 9:47:33 PM
Rank: Advanced Member

Groups: Registered
Joined: 4/30/2020
Posts: 71

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hello,

I'm wondering when we classify amino acids as polar, non-polar, acidic, basic, is that according to just the R-group alone?

For example, a molecule like glycine is considered a non-polar amino acid, but glycine as a whole is considered a polar molecule?

Could you explain why that is?

Thanks!
Back to top
Report?
INSTR_Katrina_128
#2 Posted : Friday, June 04, 2021 10:28:01 PM
Rank: Advanced Member

Groups: Registered
Joined: 5/18/2021
Posts: 73

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
I agree, this can get very confusing!

When you are asked to classify amino acids based on polarity, YES, you focus only on the R-group. That is because all amino acids have the same basic structure, and differ only in this group! https://s3-us-west-2.ama...36/figure-03-04-01.jpeg

Here is a great summary of the polarity of amino acids: https://s3-us-west-2.ama...938/figure-03-04-02.png

Like you've said with glycine, the R group is an H atom, which is non-polar. So, the unique part that makes the amino acid glycine (the glycine residue) is non-polar.

But, when we consider glycine as an entire molecule (taking into account the rest of the protein structure), we can see that it consists of a C-NH2 group (polar), a CH2 group (non-polar), and a COOH group (polar). Both of these groups (C-NH2 and COOH) are capable of gaining formal charges under the right conditions.

https://lh3.googleuserco...SLT1i65pxxAWH-r1RwqT0cds
Back to top
Report?
Users browsing this topic
Guest (2)
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.070 seconds.