Amino Acids

Summary

In this educational video, Professor Dave explains the basics of amino acids, which are monomers that form proteins. He covers their structure, including the amino and carboxyl groups, and the variable R-group that determines their properties. He also discusses the different forms amino acids can take depending on pH, such as cationic, zwitterionic, and anionic forms, and hints at their role in forming complex proteins in the body.

Takeaways

• 🧬 Amino acids are the monomers that form proteins, which are large biomolecules in the body.
• 🌐 Amino acids consist of an amino group, a carboxyl group, and a variable side chain (R-group) attached to the alpha carbon.
• 🌟 The R-group varies among different amino acids, determining their unique structures and reactivities.
• 🍽️ There are about 20 different amino acids, some of which are essential and must be obtained through diet, while others are non-essential and can be synthesized by the body.
• 🌊 Amino acids can exist in different forms (cationic, zwitterionic, anionic) depending on the pH of their environment, with the zwitterionic form being dominant at physiological pH.
• 🔋 The amino group can be protonated and the carboxyl group can be deprotonated, affecting the overall charge of the amino acid.
• 💧 The pH of the body is regulated to be close to neutral, which influences the predominant form of amino acids in biological systems.
• 🌱 The side chains of amino acids, such as lysine, can also vary in protonation states, affecting their chemical properties.
• 🔗 Amino acids polymerize to form proteins, which are crucial for various functions in the body.
• 📚 Understanding the chemistry of amino acids and their polymerization is fundamental to studying biochemistry and the roles of proteins in the body.

Q & A

What are biomolecules?

Biomolecules are large molecules found in the body, including proteins, carbohydrates, lipids, and nucleic acids. They are typically polymers made up of repeating units called monomers.

What is a monomer?

A monomer is a single unit that can join with other similar units to form a polymer. It is the basic building block of many biological molecules.

What is an amino acid and what are its key structural features?

An amino acid is a type of monomer that has an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end. The carbon between these functional groups is called the alpha carbon and it bears a side chain, which varies among different amino acids.

How does the side chain (R-group) of an amino acid affect its properties?

The R-group of an amino acid determines its chemical properties. Different R-groups can make an amino acid hydrophobic, aromatic, basic, acidic, or capable of acting as a nucleophile.

What are essential amino acids and why are they important?

Essential amino acids are those that humans cannot synthesize on their own and must be obtained through diet. They are crucial for various biological processes and protein synthesis.

What are non-essential amino acids?

Non-essential amino acids are those that the human body can produce internally, so they do not need to be consumed through diet.

What forms can an amino acid take in different pH environments?

An amino acid can exist in cationic, zwitterionic, or anionic forms depending on the pH of its environment. The zwitterionic form is typically dominant at physiological pH.

What is the significance of the zwitterionic form of an amino acid?

The zwitterionic form of an amino acid has both a positive and negative charge, which is crucial for its solubility and interaction with other molecules in biological systems.

How do amino acids polymerize to form proteins?

Amino acids polymerize by linking together through peptide bonds, forming long chains that fold into specific structures to create proteins.

What is the role of pH in the protonation and deprotonation of amino acids?

The pH of the environment affects the protonation state of the amino and carboxyl groups in amino acids. A more acidic environment favors the cationic form, while a more basic environment favors the anionic form.

Why is the pH of the body regulated so precisely?

Precise pH regulation is essential for maintaining the optimal form and function of biomolecules, including amino acids and proteins, which are sensitive to changes in pH.

Outlines

00:00

🧬 Introduction to Amino Acids and Biomolecules

Professor Dave introduces the concept of biomolecules, which are large molecules found in the body. He explains that biomolecules include proteins, carbohydrates, lipids, and nucleic acids, all of which are polymers made up of repeating units called monomers. The focus then shifts to amino acids, which are the monomers that form proteins. Amino acids have a common structure with an amino group, a carboxyl group, and a variable side chain (R-group) that determines their properties. Professor Dave also discusses the different types of amino acids, such as hydrophobic, aromatic, basic, acidic, and nucleophilic, and distinguishes between essential and non-essential amino acids. He concludes by mentioning the equilibrium between different forms of amino acids in the body, such as cationic, zwitterionic, and anionic forms, which depend on the pH of the environment.

Keywords

💡Amino Acids

Amino acids are the fundamental building blocks of proteins. They are organic compounds that contain an amino group (-NH2), a carboxyl group (-COOH), and a side chain (R-group) attached to a central carbon atom. In the video, Professor Dave explains that each amino acid has a unique R-group, which determines its properties and how it interacts with other amino acids. This is crucial for understanding how proteins are formed and function in the body.

💡Biomolecules

Biomolecules are large molecules that are essential for life processes. They include proteins, carbohydrates, lipids, and nucleic acids. These molecules are polymers made up of repeating units called monomers. The video emphasizes the importance of understanding biomolecules in the context of biochemistry, as they perform various complex functions in the body.

💡Proteins

Proteins are large biomolecules that are composed of one or more chains of amino acids. They are crucial for the structure, function, and regulation of the body's cells, tissues, and organs. In the video, Professor Dave discusses how amino acids polymerize to form proteins, highlighting the significance of the R-group in determining the protein's structure and function.

💡Carbohydrates

Carbohydrates are a class of biomolecules that include sugars, starches, and cellulose. They are primarily used by the body for energy and are also a component of cell walls. The video mentions carbohydrates as one of the classes of biomolecules, indicating their role in the body's energy metabolism.

💡Lipids

Lipids are a diverse group of biomolecules that include fats, oils, waxes, and sterols. They play a critical role in energy storage, cell membrane structure, and as signaling molecules. The video briefly mentions lipids as part of the broader category of biomolecules, emphasizing their importance in cellular functions.

💡Nucleic Acids

Nucleic acids are biomolecules that include DNA and RNA. They are responsible for storing and transmitting genetic information in cells. The video mentions nucleic acids as one of the classes of biomolecules, indicating their fundamental role in life processes.

💡Monomer

A monomer is a small molecule that can undergo polymerization to form a polymer. In the context of the video, amino acids are monomers that join together to form proteins. Understanding the properties of monomers is essential for grasping how larger biomolecules are constructed.

💡Polymer

A polymer is a large molecule composed of repeating structural units called monomers. In the video, Professor Dave explains that proteins are polymers formed by the linking of amino acid monomers. The structure and function of a polymer depend on the type and arrangement of its monomers.

💡Alpha Carbon

The alpha carbon is the central carbon atom in an amino acid molecule that bears the amino group, the carboxyl group, and the side chain (R-group). It is crucial for the structure of amino acids and their ability to form proteins. The video mentions the alpha carbon as the point of attachment for the R-group, which varies among different amino acids.

💡Essential Amino Acids

Essential amino acids are those that the human body cannot synthesize on its own and must be obtained through diet. They are crucial for various bodily functions, including protein synthesis. The video mentions essential amino acids as a subset of amino acids that humans need to consume to maintain health.

💡Non-Essential Amino Acids

Non-essential amino acids are those that the body can synthesize on its own and are not required to be obtained through diet. They can still be obtained from food but are not critical for survival in the same way as essential amino acids. The video distinguishes non-essential amino acids from essential ones, highlighting their different roles in nutrition.

💡Zwitterionic Form

The zwitterionic form is a state in which an amino acid molecule has both a positive and negative charge. This form is typically dominant at physiological pH, as it balances the slight acidity of the carboxyl group and the slight basicity of the amino group. The video explains that the zwitterionic form is important for understanding how amino acids interact in the body.

Highlights

Introduction to biomolecules and the importance of understanding their different classes.

Explanation of the concept of monomers and polymers in the context of biomolecules.

Introduction to amino acids as the first type of monomer and their basic structure.

Description of the alpha carbon and its role in amino acids with the attached side chain or R-group.

Differentiation between various amino acids based on their unique R-groups.

Classification of amino acids into hydrophobic, aromatic, basic, acidic, and nucleophilic based on their R-groups.

Identification of glycine as the simplest amino acid with a hydrogen atom as its R-group.

Differentiation between essential and non-essential amino acids based on human body's ability to produce them.

Discussion on the equilibria between different forms of amino acids in the body, including cationic, zwitterionic, and anionic forms.

Explanation of how the pH of the environment affects the form an amino acid takes.

Importance of the zwitterionic form of amino acids at physiological pH.

The potential for side chains to have different states of protonation or deprotonation depending on pH.

Example of alanine at physiological pH and its zwitterionic form.

Introduction to the polymerization process of amino acids to form proteins.

Invitation to subscribe for more tutorials and contact information for further inquiries.

Transcripts

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: