Introduction to Amino Acids and Proteins

The building blocks of proteins, consisting of a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a side chain (R group) that varies between amino acids.

The amide bond formed when two amino acids join together, linking the carboxyl group of one amino acid to the amino group of another, releasing a water molecule in the process.

A long chain of amino acids linked together by peptide bonds. Each amino acid has a unique side chain.

The three-dimensional shape of a protein, formed by the interactions between its amino acid side chains. This shape is crucial for a protein's function.

They are biological catalysts that speed up chemical reactions within cells, allowing them to occur at a much faster rate. Without enzymes, many essential biological processes would happen far too slowly to sustain life.

Molecules that bind to specific target molecules, like hormones or signaling molecules, triggering a response in the cell.

Proteins that help transport molecules across cell membranes, controlling the flow of substances in and out of cells, playing a crucial role in maintaining cell function.

Proteins that form the framework and structure of cells and tissues, providing support, strength, and elasticity. They are essential for maintaining the shape of cells, organs, and the body.

Amino acids are classified based on the location of the amino group relative to the carboxylic acid group on the parent chain. For example, an alpha (α)-amino acid has the amino group attached to the carbon atom adjacent to the carboxyl group.

Natural proteins are primarily composed of L-alpha-amino acids, which means the amino group is on the left side when the molecule is in a specific configuration.

While hundreds of amino acids exist, only 20 are commonly found in proteins, and these are called standard amino acids. Their inclusion in proteins is dictated by the genetic code.

Glycine is the simplest standard amino acid, with a hydrogen atom as its side chain. All other standard amino acids are chiral, meaning they have a non-superimposable mirror image.

The differences among standard amino acids lie in their side chains (R groups). These side chains vary in structure, size, polarity, and charge, leading to diverse properties of the amino acid.

The R group can be a simple hydrogen or an alkyl group. Alternatively, it can contain alcohol, sulfur, or a secondary amino group, or be part of a ring system.

The 20 standard amino acids are often grouped based on the properties of their side chains. This grouping helps understand how the amino acids will interact with each other and influence the overall structure and function of a protein.

Amino acids with one amino group and two carbonyl groups can be acidic due to the presence of two carboxyl groups. They are important for various metabolic processes.

Glycine, Alanine, Valine, Leucine, Isoleucine, Serine, Threonine, Cysteine, Methionine, Proline, Phenylalanine, Tyrosine, Tryptophan are all amino acids containing one amino group and one carbonyl group. These amino acids are the building blocks of proteins and play vital roles in diverse biological processes.

Aspartic acid and Glutamic acid are acidic amino acids with one amino group and two carbonyl groups. They are involved in many metabolic and signaling pathways.

Asparagine and Glutamine are amide-containing amino acids with one amino group and two carbonyl groups. These amino acids are involved in protein synthesis and nitrogen metabolism.

Lysine, Arginine, and Histidine are basic amino acids with one carbonyl group and two amino groups. Their basic nature is crucial for their function in various biological processes, including protein structure and enzymatic activity.

The isoelectric point is the pH at which an amino acid has no net charge. It is determined by the relative strengths of its acidic and basic groups. The isoelectric point of an amino acid influences its behavior in solution and its interaction with other molecules.

Amino acids with non-polar R groups are hydrophobic, meaning they tend to avoid water. They are typically found in the interior of proteins, away from the watery environment of the cell.

Amino acids with polar R groups are hydrophilic, meaning they interact readily with water. They are often found on the surface of proteins, interacting with the aqueous environment of the cell.

The R group of an amino acid is the side chain that varies between different amino acids. The R group determines the amino acid's unique properties, including size, charge, and polarity.

A three-letter code is often used to abbreviate amino acids, derived from their trivial names. This shorthand notation simplifies naming and understanding amino acid sequences in proteins.

Proteins that contain all the essential amino acids in the required amounts for human health.

Proteins lacking one or more essential amino acids, making them less nutritionally valuable.

Animal-based proteins (meat, fish, eggs) are usually complete proteins, meaning they provide all the essential amino acids in adequate amounts.

Plant-based proteins (rice, wheat, beans) often lack some essential amino acids, making them incomplete proteins.

Combining different plant-based proteins can create a complete protein source by complementing each other's missing amino acids.

Amino acids with a neutral charge at neutral pH, meaning they don't have a net positive or negative charge. These amino acids have side chains that don't carry a charge at physiological pH.

The process of adding a phosphate group to a molecule, often a protein, usually to serine, threonine or tyrosine amino acids.

A molecule with both a positive and negative charge, but with a net neutral charge.

The pH at which an amino acid has a net neutral charge. This is usually around pH 7, which is the physiological pH of the body.

Amino acids that cannot be synthesized by the human body and must be obtained from the diet. These are essential for growth, development, and maintaining good health.

The breakdown of proteins into individual amino acids, usually by enzymes called proteases.

The process by which individual amino acids are linked together to form proteins, following the instructions encoded in DNA.

The primary source of essential amino acids for humans. Breaking down proteins into their individual amino acids provides the body with the building blocks for its own proteins.