b1.2 proteins

carboxyl group, amino group, H atom, and unique organic side chain (R group)

water

N-terminal end has a free amino group, and C-terminal end has an unbound carboxyl group

They cannot be produced by the body and must be obtained from food for proper growth, maintenance, and repair of tissues and organs.

Essential amino acids cannot be produced by the body and must be obtained from food, whereas non-essential amino acids can be produced by the body from other amino acids or protein breakdown.

One end of the protein must have an amine group, and the other end must have a carboxyl group.

The genetic code provides instructions for the synthesis of proteins through transcription and translation, where DNA is transcribed into mRNA and then translated into the sequence of amino acids that make up proteins.

Codons are groups of three nucleotides that specify the type of amino acid or stop signal required, and there are 64 different codons in total, but only 20 amino acids, making the genetic code degenerate.

Lysozyme, a polypeptide composed of 129 amino acids, has antimicrobial properties, disrupting the cell walls of certain bacteria, and is present in tears and saliva.

Glucagon, a polypeptide composed of 29 amino acid residues, regulates blood sugar levels by releasing glucose.

Myoglobin, a polypeptide composed of 153 amino acid residues, is an oxygen binding protein that facilitates the storage and release of oxygen to muscle fibers during strenuous physical activity.

Polypeptides are necessary for the proper growth, maintenance, and repair of the body's tissues and organs because they serve as both enzymes and hormones, facilitating various cellular functions.

The R group of amino acids determines the properties of the assembled polypeptides.

Hydrogen bonds between the carboxyl group of one amino acid and the amino group of another amino acid.

A specific sequence of amino acids that are joined together to form a polypeptide chain.

They are polar or charged, and attract water molecules.

They stabilize the three-dimensional shape by holding distant regions of the polypeptide chain together.

Ionic bonds.

They clump together into hydrophobic clusters to minimize contact with surrounding water molecules.

Hydrophilic polar amino acids face the aqueous environment, while hydrophobic non-polar amino acids are protected in the core, minimizing unfavourable interactions with water molecules.

They help to maintain the protein's 3D shape by forming covalent bonds between pairs of cysteine amino acid residues.

The interaction between R groups determines the further folding of the polypeptide, resulting in the tertiary structure.

The hydrophilic exterior of insulin allows it to react with water and other hydrophilic molecules in the blood.

Collagen is a fibrous protein with a triple helix structure, composed of 3 polypeptide chains twisted together, rich in glycine, proline, and hydroxyproline residues, which helps maintain its shape and provides strength and stability.

Fibrous proteins have a long and narrow shape (elongated), designed for strength and stability, whereas globular proteins have a compact and globular shape.

The hydrophobic interior of insulin stabilizes the shape of the protein and maintains its globular shape.

The residues responsible for the twisting of the polypeptide chains in collagen are glycine, proline, and hydroxyproline, which are held together by hydrogen bonds and van der Waals forces.

The quaternary structure of a protein is the arrangement and interaction of two or more polypeptide chains to form a functional protein. An example is haemoglobin, which consists of four individual polypeptide chains, two alpha chains and two beta chains.

Conjugated proteins are proteins that have non-protein components such as metal ions or carbohydrates in addition to polypeptide subunits, whereas non-conjugated proteins consist only of polypeptide subunits.

The process involved in the formation of a protein's 3D shape is protein folding, which is influenced by factors such as hydrogen bonding, ionic bonding, hydrophobic interaction, and the sequence of amino acids in the protein.

Globular proteins have a spherical or irregular shape, are soluble in water, and function as transporters, regulators, and enzymes.

The haem group in haemoglobin is responsible for binding to oxygen in the lungs, facilitating the transport of oxygen throughout the body.

Haemoglobin has a quaternary structure that consists of four subunits held together by non-covalent bonds, and it is classified as a globular protein due to its spherical shape and solubility in water.