Biological Molecules

A comprehensive set of vocabulary flashcards covering biological molecules, carbohydrates, lipids, proteins, enzymes, nucleic acids, and the properties of water and inorganic ions based on the lecture notes.

Monomer

The smaller units from which larger molecules are made.

Polymer

Molecules made from a large number of monomers joined together.

Monosaccharide

The monomers from which larger carbohydrates are made, including glucose, fructose, and galactose.

Disaccharide

Formed by the condensation of two monosaccharides held together by a glycosidic bond.

Polysaccharide

Formed by the condensation of many glucose units held by glycosidic bonds, such as starch, glycogen, and cellulose.

Glycosidic bond

A covalent $C-O-C$ link between two sugar molecules formed by a condensation reaction.

Amylose

A polysaccharide in starch made of $\alpha$-glucose joined by $1,4$-glycosidic bonds that coils to form a helix.

Amylopectin

A polysaccharide in starch made of $\alpha$-glucose joined by $1,4$ and $1,6$-glycosidic bonds with a branched structure.

Condensation reaction

A reaction that joins two molecules together with the formation of a chemical bond and the elimination of a molecule of water.

Hydrolysis reaction

A reaction that breaks a chemical bond between two molecules and involves the use of a water molecule.

Triglyceride

Formed by the condensation of one molecule of glycerol and three molecules of fatty acids, forming $3$ ester bonds.

Phospholipid

Formed by the condensation of one molecule of glycerol and two molecules of fatty acid held by two ester bonds, with a phosphate group attached to the glycerol.

Ester bond

The $-COO-$ chemical bond formed between glycerol and fatty acids via a condensation reaction.

Competitive inhibitor

A molecule with a similar shape to the substrate that binds to the active site, preventing enzyme-substrate complexes from forming.

Non-competitive inhibitor

A molecule that binds to an enzyme at the allosteric site, causing the active site to change shape and preventing enzyme-substrate complexes from forming.

Induced-fit model

A model where the enzyme active site is not initially complementary to the substrate but moulds around it, putting tension on bonds and lowering the activation energy.

Primary structure

The sequence of amino acids on a polypeptide chain held by peptide bonds.

Secondary structure

The folding or coiling of a polypeptide to create a $\beta$ pleated sheet or an $\alpha$ helix, held in place by hydrogen bonds.

Tertiary structure

The further folding to create a unique $3D$ shape, held in place by hydrogen, ionic, and sometimes disulfide bonds.

Quaternary structure

The structure formed when a protein consists of more than one polypeptide chain.

Peptide bond

A covalent $C-N$ link between an amine group and carboxyl group of two different amino acids, formed by a condensation reaction.

Isomer

Molecules with the same molecular formula but where the atoms are arranged differently, such as $\alpha$ glucose and $\beta$ glucose.

Maltose

A disaccharide formed by the condensation of two glucose molecules.

Sucrose

A disaccharide formed by the condensation of a glucose molecule and a fructose molecule; it is a non-reducing sugar.

Lactose

A disaccharide formed by the condensation of a glucose molecule and a galactose molecule.

Amino acid

The monomer of a protein formed from $C, H, O, N$ containing a carboxyl group, amine group, an $H$, a central carbon, and a variable $R$ group.

Activation energy

The minimum amount of energy required for a reaction to occur.

Saturated fatty acid

A long hydrocarbon chain with a carboxyl group at one end containing only single bonds between carbon atoms.

Unsaturated fatty acid

A long hydrocarbon chain with a carboxyl group at one end containing at least one double bond between carbon atoms.

Reducing sugar

Sugars that can reduce $Cu^{2+}$ ions in Benedict’s reagent to $Cu^{+}$ ions in the form of copper (I) oxide, forming a brick-red precipitate.

Phosphodiester bond

A bond joining two adjacent nucleotides together, formed between a phosphate group and the pentose sugar via a condensation reaction.

Semi-conservative replication

DNA replication where each new DNA molecule contains one original parental strand and one newly synthesised strand.

DNA helicase

An enzyme that breaks hydrogen bonds between the two chains of DNA in a double helix to separate the strands during replication.

DNA polymerase

An enzyme involved in DNA replication that joins together adjacent nucleotides.

High specific heat capacity

The property of water where a lot of energy is required to raise its temperature because heat is used to break hydrogen bonds, allowing it to act as a temperature buffer.

Large latent heat of vaporisation

The property of water where significant energy is required to convert it from liquid to gas, providing a cooling effect.

Strong cohesion

The tendency of water molecules to stick together due to hydrogen bonds, allowing water to move up the xylem in a continuous column.

ATP synthase

An enzyme that catalyses the synthesis of ATP from $ADP + Pi$.

ATP hydrolase

An enzyme that catalyses the hydrolysis of ATP into $ADP + Pi$.

Inorganic ions

Ions occurring in solution in the cytoplasm and body fluids, including $H^{+}$ (pH), $Fe^{2+}$ (haemoglobin), $Na^{+}$ (co-transport), and $PO_4^{3-}$ (DNA/ATP).