Amino Acids

Amino Acids


Professor Dave here, let’s talk about amino acids. Your body is full of large
molecules called biomolecules, and the first thing we have to do to understand
biochemistry is to learn about the different kinds of biomolecules. There
are a few different classes like proteins, carbohydrates, lipids, and
nucleic acids, and most of them are polymers that are comprised of repeating
units called monomers. Mono means one, poly means many, so a polymer is formed
when many monomers link together. Each polymer has its own type of monomer so
we need to know about these different kinds of monomeric units, and the ways
they combine to form the large molecules that do all the complex things in your body. The first type of monomer we will learn
about is the amino acid. Amino acids look like this. They all have an amino group on one end
and a carboxyl group on the other end. The carbon in between those functional
groups, which we call the alpha carbon, will bear a side chain, sometimes referred
to as an R-group. This is a group that varies depending on which amino acid we
are looking at. If the R group is just a hydrogen atom, we call this amino acid
glycine. If it’s a methyl group, we call this alanine. There are about 20 of them
and they have a wide variety of R groups that can be put into different categories. Some of them will be hydrophobic, like
leucine. These are the ones with R groups that are alkyl substituents. Some
of them have R groups that are aromatic, like phenylalanine. Some have R groups that are basic, like lysine, because of the lone pair of electrons on
the nitrogen atom. Some have R groups that are acidic, like aspartic acid,
because of the carboxyl group. Some have R groups that can act as nucleophiles,
like serine, because of the hydroxyl group. Every amino acid has its own unique
structure and reactivity, and it’s the variation in these R groups that determines the
characteristics of the molecule that forms when a bunch of these amino acids
join together. Some of these amino acids humans can’t make on their own, so
we have to eat them in our diet. They are called essential amino acids. Others we
are able to make inside our bodies so those are called non-essential amino
acids, meaning it’s not essential that we eat them. So amino acids are monomers and
monomers are the units that join together to form a polymer. How exactly
then do amino acids polymerize? Before we learn about that let’s first understand that inside the
body, instead of the one structure we’ve been looking at, there are actually
equilibria between different forms of the amino acid. The amino group can be
protonated, since it is slightly basic, and the carboxyl group can be
deprotonated, since it is slightly acidic, and there are equilibria between the
cationic form, the zwitterionic form, and the anionic form. We know what cations
and anions are, they are positively charged and negatively charged species.
And a zwitterion is a molecule that has both a positive and negative charge. The
form that an amino acid will take depends on the pH of its environment. A
more acidic solution will favor the cationic form since basic groups will
pick up protons from the hydronium in solution, and a more basic solution will
favor the anionic form, since acidic groups will readily deprotonate in the
presence of hydroxide inside the body. The pH is regulated very precisely and
in most areas it’s fairly close to neutral pH, so the zwitterionic form is
typically dominant. The side chains can also have different states of
protonation or deprotonation depending on the pH, such as lysine, where the R
group can have NH2 or NH3+. For now, let’s just look at something simple like
alanine. At physiological pH it will take this form. What sort of chemistry can this do? It
might not be obvious just looking at it, but with the help of other molecules in the body
these can polymerize to form proteins so let’s move ahead and learn all about
proteins. Thanks for watching, guys. Subscribe to my channel for more tutorials, and as always feel free to email me:

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100 thoughts on “Amino Acids

  1. I thought that these mentioned 20 amino acids are all essential for proteins in animals. There are many other amino acids which dont build protein, as in plants??
    Hi Dave….why do you say that only half of these 20 amino acids are 'essential'???

  2. Your videos are extremely helpful for my science classes. Have you considered creating a PROFESSOR DAVE EXPLAINS app? I think it would be a very popular app!

  3. The substitution of a single amino acid in a cell receptor might have a significant effect on the receptor's structure and function. Can you explain an example. How about disease were a receptor is affected?

  4. i love how you stand so awkwardly but your voice is so expressive. highly quality videos and explanations thank you so much!!!!!!! 🙏🏼🙏🏼🙏🏼

  5. Thank you for making a video where you SPEAK on a subject that I searched for. So many videos on amino acids are just musical power points with no narration. I don't want to sound like a dumb tool, but when I visit YouTube it isn't because I'm itching for a good read.
    Much appreciated!

  6. Thank you so much for these helpful lectures. They all make my preparation for med school entrance exam astoundingly less frustrating!

  7. Hi Professor Dave
    Thanks for your extensive research in the field of biochemistry and your thought imparting resilience.

  8. Would an acidic solution not favour the anionic form? Since the excess protons in the acid will then be able to neutralize the anion. Great video by the way!!

  9. So we have this huuuge chemistry exam we have to pass to be accepted for further medical school and without Professor Dave I would not be on my way to become a doctor anymore haha 😀
    Thank you so so so much!

  10. Congratulations for the channel. I think it would be nice if you put numbers at the videos so we can follow an order in the ideas.

  11. When the same science that this information comes from also says with pride and confidance only 10% of human DNA has a function instead of the truth "we dont know 90% of what DNA is , and the other 90% may change what we know think we know" as far as Im comcerned all science is a best guess based on our current level of ignorance and very potentially realized in time as the great ignorance perpetrator that may be known in time as the new relifion, as equally ignorant as its religion contemporaries….it may be a good idea to set their "religious texts" down if we are truly interested in begining to find the truth of matters of our interests, vs memorizing theorys .

  12. I cant handle this fucking idiot trying to tell me something. Not that he lies but the way he speaks and acts really makes me uncomfortable as fuck.

  13. Sir. why dont u visit a barber. ? u hv beautiful hair nd dey will make u look great. you tube vedios r in plenty. u look good as well

  14. Haha all those students like me out there…. isn't it amazing. Sometimes it is just so difficult to even try to understand what the teacher is saying in class. Then we'd be rushing around YouTube looking for saints like P.Dave

  15. Suosittelen kaikille luonnontieteistä kiinnostuneille, englantia ymmärtäville suomalaisille. Bangkok-Jomppa CarSanook Media Thaimaa

  16. Abiogenesis is an embarrassment! chemists are proving that it takes intelligent design just to copy pre-existing donor cells!!

  17. Is there any easy way to remember the difference between coding DNA, non-coding DNA, template and non-template….. it's all very confusing to me.

  18. Wow. Please change your name to “Professor Dave Saves the Day”. This will be the third class you’ve helped me study for. I don’t know what is about your videos, but they are seriously incredible for an advanced student with ADHD. I always brag on them and share them with peers.

  19. I'm a sophomore in highschool and in biology we took a biochem basics test and I made a 40 and it's worth 50% of our grade, we get to retake it tomorrow and your videos are making me confident I'm going to pass

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