Biomolecules Lecture Flashcards

Vocabulary flashcards covering biological molecules including carbohydrates, lipids, proteins, biochemical tests, and water properties.

Organic Compound

Molecules composed of one or more carbon (C) atoms covalently linked to atoms of hydrogen (H).

Monomer

Small, basic building blocks used for the synthesis of a polymer.

Polymer

A large molecule made from many similar repeating subunits joined together in a chain.

Macromolecule

Giant molecules containing thousands of atoms with a high molecular mass, which are not all polymers.

Covalent Bond

The sharing of two or more electrons between two atoms.

Anabolism

The formation of large, complex molecules by linking smaller, simpler molecules with covalent bonds, requiring ATP energy.

Catabolism

The breakdown of large, complex molecules into smaller molecules, releasing energy.

Condensation Reaction

A reaction in which smaller molecules are joined together by covalent bonds with the removal of water.

Hydrolysis Reaction

A reaction in which large, complex molecules are broken down into smaller molecules by the addition of water.

Monosaccharide

A single sugar unit that serves as a source of energy in respiration and as a building block for larger carbohydrates.

Structural Isomers

Compounds with the same chemical formula that differ in the structural arrangement of their atoms, such as $\alpha$-glucose and $\beta$-glucose.

Disaccharide

A double sugar unit formed when two monosaccharides are joined by a glycosidic bond during a condensation reaction.

Maltose

A disaccharide sugar found in germinating seeds formed by joining two glucose molecules.

Lactose

A disaccharide sugar found in mammal milk formed by joining a glucose molecule and a galactose molecule.

Sucrose

A non-reducing disaccharide sugar stored in sugar cane formed by joining carbon 1 of an $\alpha$-glucose molecule to carbon 2 of a $\beta$-fructose molecule.

Glycosidic Bond

A covalent bond formed between two monosaccharides through a condensation reaction.

Reducing Sugar

A sugar that can donate electrons to become oxidized, giving a positive result in Benedict's test.

Non-reducing Sugar

A sugar such as sucrose that cannot donate electrons, yielding a negative result with Benedict's test unless hydrolysed first.

Benedict's Test

A biochemical test for reducing sugars where boiling a liquid sample with Benedict's solution causes a colour change from bright blue to brick-red if positive.

Acid Hydrolysis

A procedure where a sample is boiled with dilute HCl and neutralised with sodium carbonate to break glycosidic bonds before testing for non-reducing sugars.

Polysaccharide

Complex carbohydrate polymers consisting of many monosaccharides linked together covalently by glycosidic linkages.

Starch

A branched storage polysaccharide in plants composed of $\alpha$-glucose units linked by 1,4 and 1,6 glycosidic bonds, consisting of amylose and amylopectin.

Amylose

An unbranched, helical starch component (10-30%) consisting of $\alpha$-glucose rings joined by $\alpha$-1,4 glycosidic bonds.

Amylopectin

A branched starch component (70-90%) consisting of $\alpha$-glucose chains linked by $\alpha$-1,4 and $\alpha$-1,6 glycosidic bonds.

Iodine Test

A biochemical test for starch where adding a drop or two of iodine solution turns the sample from orange-brown to blue-black if positive.

Glycogen

A highly branched storage polysaccharide in animals and fungi made of $\alpha$-glucose molecules bonded by $\alpha$-1,4 and $\alpha$-1,6 glycosidic linkages.

Cellulose

A linear structural polysaccharide found in plant cell walls formed by $\beta$-glucose molecules bonded by 1,4 linkages with consecutive molecules rotated $180^\text{o}$.

Ethanol Emulsion Test

A biochemical test for lipids where a sample is shaken with ethanol and added to water, forming a milky/cloudy emulsion if positive.

Triglyceride

A non-polar hydrophobic macromolecule composed of one glycerol head linked to three fatty acid tails via ester bonds.

Ester Bond

The covalent bond formed between a hydroxyl group of glycerol and the carboxyl group of a fatty acid.

Saturated Fatty Acid

A fatty acid containing only single bonds between carbons in its hydrocarbon chain, resulting in straight chains that form solid fats at room temperature.

Unsaturated Fatty Acid

A fatty acid containing one or more double bonds between carbons in its hydrocarbon chain, resulting in bent chains that form liquid oils at room temperature.

Phospholipid

An amphipathic molecule consisting of a polar hydrophilic phosphate head and two non-polar hydrophobic fatty acid tails.

Amino Acid

The monomer unit of proteins consisting of a central alpha carbon bonded to a hydrogen, an amino group, a carboxyl group, and a variable side chain (R group).

Peptide Bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another during a condensation reaction.

Biuret Test

A biochemical test for proteins where adding Biuret solution to a liquid sample results in a colour change from blue to violet/lilac if positive.

Primary Structure

The unique linear sequence of amino acids in a polypeptide chain linked together by covalent peptide bonds.

Secondary Structure

The coiling or folding of a polypeptide chain into an $\alpha$-helix or $\beta$-pleated sheet, held together by hydrogen bonds between peptide bonds.

Tertiary Structure

The compact 3D coiling and folding of a single polypeptide chain, stabilized by hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions.

Disulfide Bridge

A strong covalent bond formed between sulfur atoms of cysteine amino acids in a protein's tertiary structure.

Quaternary Structure

The protein structural level occurring in proteins that consist of two or more polypeptide chains working together as a functional macromolecule.

Globular Protein

A compact, roughly spherical protein that is generally water-soluble and has physiological roles.

Fibrous Protein

A long, strand-like protein that is generally water-insoluble and performs structural roles.

Haemoglobin

A globular protein composed of two $\alpha$-globin chains, two $\beta$-globin chains, and four iron-containing haem groups that carries oxygen.

Collagen

A fibrous structural protein consisting of three polypeptide alpha-chains wound into a tight triple helix linked by hydrogen and covalent bonds.

Specific Heat Capacity

The amount of thermal energy required to raise the temperature of $1\,\text{kg}$ of a substance by $1^\circ\text{C}$.

Latent Heat of Vaporisation

The amount of thermal energy absorbed by a liquid to break hydrogen bonds and convert into a gas state.

Cohesion

The attraction force between molecules of the same substance, such as hydrogen bonds between water molecules.

Adhesion

The attraction force between molecules of different substances.