Edexcel (B) Biology A-level: Biological Molecules

These flashcards cover key vocabulary terms and definitions related to biological molecules, including carbohydrates, lipids, proteins, DNA, and their functions.

Carbohydrates

Molecules consisting of carbon, hydrogen, and oxygen, formed in long chains of sugar units.

Monosaccharide

A single sugar monomer, the simplest form of carbohydrates.

Disaccharide

A carbohydrate formed from the condensation of two monosaccharides.

Polysaccharide

A carbohydrate that consists of many monosaccharides joined together.

Glycosidic bond

The covalent bond formed between monosaccharides in carbohydrates during condensation reactions.

Glucose

A monosaccharide with six carbon atoms, serving as the main substrate for respiration.

Ribose

A monosaccharide containing five carbon atoms, serving as a component of RNA.

Deoxyribose

An isomer of ribose found in DNA, lacking the hydroxyl group on the second carbon.

Glycogen

The main energy storage molecule in animals, formed from alpha glucose.

Starch

A plant energy storage polysaccharide, consisting of amylose and amylopectin.

Amylose

An unbranched form of starch made up of glucose molecules joined by 1,4 glycosidic bonds.

Amylopectin

A branched form of starch consisting of glucose molecules joined by both 1,4 and 1,6 glycosidic bonds.

Cellulose

A polysaccharide forming the structural component of cell walls in plants, made of beta glucose.

Lipids

Biological molecules that are soluble in organic solvents, such as alcohols, and consist largely of carbon and hydrogen.

Saturated lipids

Lipids that contain only carbon-carbon single bonds, typically solid at room temperature.

Unsaturated lipids

Lipids containing one or more carbon-carbon double bonds, typically liquid at room temperature.

Triglycerides

Lipids made of one glycerol and three fatty acids, used as energy reserves.

Phospholipids

Lipids where one fatty acid is substituted with a phosphate group, forming cell membranes.

Proteins

Molecules made from amino acids, essential for many biological functions.

Amino acids

The monomers that combine to form proteins, each having a unique R group.

Peptide bond

The bond formed between amino acids during protein synthesis.

Primary structure

The linear sequence of amino acids in a polypeptide chain.

Secondary structure

The folding of the polypeptide chain into structures like alpha helices or beta pleated sheets.

Tertiary structure

The 3D folding of a protein determined by various bonds and interactions.

Quaternary structure

The arrangement of multiple polypeptides into a functional protein.

DNA

Deoxyribonucleic acid, a nucleic acid that contains the genetic information.

RNA

Ribonucleic acid, a nucleic acid involved in protein synthesis.

Nucleotides

The building blocks of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Codon

A triplet of bases in mRNA that codes for a specific amino acid.

Enzymes

Biological catalysts that speed up chemical reactions by lowering activation energy.

Active site

The region of an enzyme where substrate molecules bind and undergo a chemical reaction.

Inhibitors

Substances that prevent the enzyme from binding to its substrate.