Biological molecules

• Polysaccharides are complex carbohydrates made up of many monosaccharide units joined together through glycosidic bonds.
• Cellulose is an insoluble structural polysaccharide that forms cell walls in plant cells.
• Starch is the main storage polysaccharide found in plants, consisting of amylose (unbranched) and amylopectin (branched).
• Glycogen is the animal equivalent of starch, with more branches than amylopectin.
• Amino acids link together in long chains to form proteins that are essential for the structure, function, and regulation of the body.
• Secondary structure involves hydrogen bonds between peptide groups that form alpha helices or beta pleated sheets.
• There are 20 standard amino acids in living organisms.
• Primary structure refers to the sequence of amino acids in a protein chain.
• The three-dimensional structure of proteins is determined by the primary, secondary, tertiary, and quaternary structures.
• Amino acids are basic molecules that form the building blocks of proteins.
• Disaccharides are carbohydrates composed of two monosaccharide units joined together through a glycosidic bond.
• Carbohydrates can have different types of structures, such as being branched or unbranched.
• Chitin is another type of polysaccharide found in the exoskeletons of insects, crustaceans, and fungi.
• Proteins are biological polymers composed of amino acids linked by peptide bonds.
• Polypeptides are chains of amino acids held together by peptide bonds.
• Secondary structure describes the local folding patterns within a polypeptide chain, including alpha helices and beta sheets.
• The primary structure of a protein refers to its sequence of amino acids.
• The general structure of an amino acid consists of: carboxyl group, amino group, central carbon atoms and an R group determining which amino acid it is.
• Fibrous proteins are long and narrow and have a tertiary structure.
• Globular proteins are rounded/spherical and have a complex tertiary or quaternary structure.
• Fibrous proteins are mostly insoluble.
• The structural aspect of fibrous proteins means they are used for strength and support.
• Globular proteins are mostly soluble and are functional meaning they are used as catalysts and transport.
• Globular proteins are more sensitive to pH than fibrous proteins.
• Some examples of fibrous proteins are collagen and keratin.
• Some examples of globular proteins are haemoglobin, insulin and amylase.
• Haemoglobin has a quaternary structure and is used to transport oxygen around the body by binding to it.
• Insulin is a quaternary structure and is secreted by the pancreas to control blood sugar levels.
• Amylase is a tertiary structure and is a catalyst enzyme converts starch into glucose by hydrolysis in the digestive system.
• Collagen is a quaternary structure and is found in skin, tendons, cartilage and bonds. It has an inelastic and flexible structure.
• Keratin is a tertiary structure which provides protection to hair and feathers. It can be flexible or strong depending on it's uses.
• Elastin is a fibrous protein with a tertiary structure. It is found in connective tissues, ligaments and joint capsules. It prevents blood vessels from bursting with high b.p. It is also elastic.
• Lipids are called macromolecules and contain O, H and C. Some contain alcohol or phosphate groups.
• Lipids consist of a glycerol backbone with 3 fatty acid tails.
• The fatty acid chain can be saturated with single carbon bonds, or unsaturated with double carbon bonds.
• Saturated fats are bonded to the maximum number of hydrogens, whilst unsaturated is bonded to less hydrogens.
• Monounsaturated means 1 double carbon bond, whilst polyunsaturated means more than 1 carbon bond.
• Cis unsaturated fats have their hydrogen on the same side of the molecule.
• Trans unsaturated fats have their hydrogens on opposite sides of a molecule.
• An ester bond forms between the carboxyl group of the fatty acid and the hydroxyl group of the glycerol back bone.