Biochemistry Chapter: Proteins and Amino Acids

Large molecules consisting of repeating units called monomers, found in living organisms. They are highly ordered with specific sequences of monomers determining their structure and function.

A group of biomolecules crucial for life, often acting as catalysts (enzymes) or structural components. They are linear chains of amino acids linked by peptide bonds.

Building blocks of proteins, small organic molecules with an amino group, a carboxyl group, and a side chain specific to each amino acid.

The bond formed between two amino acids, linking them together in a protein chain. It's a covalent bond between the carboxyl group of one amino acid and the amino group of the next.

Each protein has a unique sequence of amino acids, determining its specific structure and function. This sequence acts as a 'code' for the protein's behavior.

The three-dimensional shape of a protein is directly determined by its amino acid sequence. This shape dictates its function.

The process of unfolding or disrupting a protein's shape, which often leads to loss of function.

These interactions play a key role in protein folding and stability, shaping the protein's three-dimensional structure and influencing its function. They are weaker than covalent bonds but essential for overall structure.

Two amino acids joined together by a peptide bond.

A chain of amino acids ranging from 3 to 10 units.

A long chain of amino acids, typically containing over 10 units.

Proteins that consist of more than one polypeptide chain joined together.

Proteins with a non-amino acid component attached, like lipids, sugars, or metals.

The arrangement of secondary structures (alpha helices and beta sheets) within a single polypeptide chain.

A distinct, compact, folded unit within a protein, usually with a specific function.

The forces that stabilize the tertiary structure of a protein, including hydrogen bonds, hydrophobic interactions, electrostatic interactions, and van der Waals forces.

Proteins with long, extended polypeptide chains, often arranged in strands or sheets, providing structural support.

Proteins with polypeptide chains folded into compact, spherical shapes, usually involved in enzymatic activity or regulation.

Beta sheets are formed by stretches of polypeptide chains aligned side by side, stabilized by hydrogen bonds between the backbone atoms. The R groups of adjacent residues point in opposite directions, creating a pleated appearance.

A type of secondary structure in which the polypeptide backbone is coiled into a helical shape, stabilized by hydrogen bonds between the backbone atoms.

Refers to the arrangement of multiple polypeptide chains (subunits) in a protein complex.

A type of protein formed by the breakdown of native proteins, typically through digestion, where the amino acid sequence remains intact but the structure is altered.

A protein that acts as a catalyst, speeding up biochemical reactions in the body.

The linear sequence of amino acids in a protein, linked by peptide bonds. It's like the 'blueprint' for the protein's structure and function.

A protein that helps transport molecules throughout the body, like oxygen or iron.

Proteins that provide structural support and shape to cells and tissues, like collagen in skin or elastin in blood vessels.

The 3D shape of a protein, determined by its amino acid sequence and various interactions between the side chains. It defines the protein's function.

Proteins that are involved in the immune system by recognizing and fighting off foreign invaders.

Proteins that enable muscle movement, like actin and myosin.

The simplest category of proteins composed only of amino acid chains, without any additional components.

The unique chemical group attached to the alpha carbon of an amino acid, determining its specific properties.

The side chain's ability to interact with water. Hydrophobic R groups repel water (water-insoluble), whereas hydrophilic R groups attract water (water-soluble).

A carbon atom bonded to four different atoms or groups. Its tetrahedral arrangement leads to the formation of two non-superimposable mirror image forms of an amino acid: enantiomers.

Two molecules that are mirror images of each other but cannot be superimposed. Amino acids can exist as two enantiomers: L and D forms.

A classification of amino acids based on the chemical properties of their R groups, particularly their polarity. There are five main classes: nonpolar (hydrophobic), aromatic, polar uncharged, positively charged (basic), and negatively charged (acidic).

The tendency of nonpolar amino acids to cluster together within a protein, driven by their aversion to water. This interaction stabilizes protein structure.

Amino acids with nonpolar, aliphatic side chains, such as alanine, valine, leucine, and isoleucine. These R groups tend to cluster together within proteins due to the hydrophobic effect.

Glycine, an amino acid with the simplest structure. Its small size doesn't contribute significantly to hydrophobic interactions.

Amino acids with aromatic side chains, such as phenylalanine, tyrosine, and tryptophan. They are relatively nonpolar and contribute to the hydrophobic effect.

Amino acids with a hydroxyl group in their R group, such as serine and threonine. Their hydroxyl group makes them more soluble in water due to the ability to form hydrogen bonds.

Amino acids with a sulfhydryl (SH) group in their R group, such as cysteine. Their polarity is modest, forming weak hydrogen bonds with oxygen or nitrogen. Cysteine can form a disulfide bond with another cysteine molecule.

Amino acids with positively charged R groups, such as lysine, arginine, and histidine. These R groups interact strongly with water and contribute to the hydrophilic nature of proteins.

Amino acids with negatively charged R groups, such as aspartate and glutamate. These R groups are highly hydrophilic and readily interact with water.

Amino acids that are not commonly used in protein synthesis but play important roles in the body. Examples include 4-hydroxyproline, pyrrolysine, citrulline, ornithine, taurine, L-DOPA, and GABA.

The ability of amino acids to act as both acids and bases due to the presence of functional groups like amino groups, carboxyl groups, and ionizable R groups. At neutral pH, amino acids exist as zwitterions, molecules with both positive and negative charges.

The process of joining amino acids together to form polypeptide chains. This is a condensation reaction where a water molecule is removed for each bond formed. Peptide bonds are broken by hydrolysis, the addition of water.

A protein found in muscle tissue that stores oxygen, enabling muscles to work efficiently.

A protein with two polypeptide subunits, forming a complex structure.

Proteins that consist of multiple polypeptide chains (subunits).

Amino acids that the body cannot synthesize and must be obtained from the diet. These are essential for growth and repair.

The amount of protein needed daily varies depending on age, activity levels, and health status. The recommended daily intake (RDA) for healthy adults is 0.8 to 1.0 g/kg/day.

Foods like beans, soy, meat, milk, and dairy products that provide essential amino acids needed for the body to build and maintain tissues. Combining various protein sources ensures a complete set of amino acids.