Biological Molecules: Carbohydrates, Lipids, Proteins, Nucleic Acids, ATP, and Water

Vocabulary practice flashcards covering monomers, polymers, carbohydrates, lipids, proteins, enzymes, nucleic acids, ATP, and water based on biology lecture notes.

Monomer

A small unit that serves as a component of larger molecules, such as monosaccharides, amino acids, and nucleotides.

Polymer

A large molecule made from many monomers joined together by chemical bonds.

Condensation reaction

A chemical reaction in which two molecules are joined together by a chemical bond with the elimination of a water molecule.

Hydrolysis

A chemical reaction in which a chemical bond between two molecules is broken through the addition of a water molecule.

Monosaccharide

A single sugar monomer containing carbon, hydrogen, and oxygen with the general formula $(CH_2O)_n$, where $n$ is any number from $3$ to $7$.

Disaccharide

A carbohydrate formed when two monosaccharides join together in a condensation reaction by forming a glycosidic bond.

Glycosidic bond

A chemical bond formed in a condensation reaction between two saccharides.

Maltose

A disaccharide formed by the condensation of two glucose molecules linked by a $1,4$ glycosidic bond.

Sucrose

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

Lactose

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

Glycogen

The main insoluble, compact energy storage polysaccharide in animals, formed from many alpha glucose molecules joined by $1,4$ and $1,6$ glycosidic bonds with many side branches.

Amylose

An unbranched, coiled, compact plant energy storage polysaccharide component of starch made of glucose molecules joined by $1,4$ glycosidic bonds.

Amylopectin

A branched polysaccharide component of starch made of glucose molecules joined by $1,4$ and $1,6$ glycosidic bonds that can be rapidly broken down by multiple enzymes simultaneously.

Cellulose

A structural plant cell wall polysaccharide composed of long, unbranched chains of beta glucose joined by glycosidic bonds.

Microfibrils

Strong threads formed from long cellulose chains running parallel to one another, cross-linked by hydrogen bonds to stop plant cell walls from bursting under osmotic pressure.

Benedict's reagent

An alkaline solution of Copper(II) Sulfate that tests for reducing sugars, forming an insoluble brick-red precipitate of copper (I) oxide upon heating.

Triglyceride

A lipid formed by condensation reactions joining one molecule of glycerol to three fatty acid molecules with ester bonds.

Saturated lipid

A lipid, such as an animal fat, whose hydrocarbon chain contains no carbon-carbon double bonds.

Unsaturated lipid

A lipid, such as a plant fat, that contains carbon-carbon double bonds causing bends in the hydrocarbon chain, preventing tight packing and making it liquid at room temperature.

Phospholipid

A polar lipid formed when one fatty acid of a triglyceride is replaced by a phosphate-containing group, resulting in a hydrophilic head and two hydrophobic tails.

Emulsion test

A biochemical test for lipids where the sample is dissolved in $5\,cm^3$ of ethanol and mixed with $5\,cm^3$ of water, forming a cloudy-white layer in a positive result.

Amino acid

The monomer from which proteins are made, composed of an amino group ($NH_2$), a carboxylic acid group ($-COOH$), and a variable carbon-containing $R$ group.

Primary structure of a protein

The unique sequence, order, and number of amino acids in a protein's polypeptide chain that determines its ultimate function.

Secondary structure of a protein

The spatial shape formed by a polypeptide chain into an alpha helix or beta pleated sheet, stabilized by weak hydrogen bonds between $-NH$ and $-C=O$ groups.

Tertiary structure of a protein

The specific 3D twisting and folding of a protein, maintained by disulfide bridges, ionic bonds, and hydrogen bonds.

Biuret test

A chemical test for proteins and peptide bonds using sodium hydroxide and dilute ($0.05\%$) copper (II) sulfate solution, which turns purple in a positive result.

Active site

A small depression on an enzyme formed by only a few amino acids that binds specifically to a complementary substrate.

Induced fit model

A model of enzyme action where the binding of a substrate alters the enzyme's structure so that the active site fits snugly around the substrate to form an enzyme-substrate complex.

Competitive reversible inhibitor

A substance that decreases the rate of an enzyme-controlled reaction by temporarily binding to and blocking the enzyme's active site.

Non-competitive reversible inhibitor

A substance that decreases the rate of an enzyme-controlled reaction by binding to the enzyme at a site other than the active site, altering the enzyme's shape.

Nucleotide

The monomer of nucleic acids, consisting of a five-carbon pentose sugar, a nitrogen-containing organic base, and a phosphate group.

Phosphodiester bond

A covalent bond formed in a condensation reaction between the pentose sugar of one nucleotide and the phosphate group of an adjacent nucleotide.

DNA helicase

An enzyme that breaks the hydrogen bonds between complementary base pairs to separate the two strands of DNA during semi-conservative replication.

DNA polymerase

An enzyme that joins activated complementary nucleotides together by forming phosphodiester bonds during semi-conservative replication.

Adenosine triphosphate (ATP)

An immediate cellular energy source and nucleotide derivative composed of ribose, adenine, and three phosphate groups.

ATP hydrolase

An enzyme that catalyses the hydrolysis of ATP into adenosine diphosphate (ADP) and an inorganic phosphate molecule, releasing energy.

ATP synthase

An enzyme that catalyses the condensation reaction between ADP and an inorganic phosphate to reform ATP during photosynthesis and respiration.

Specific heat capacity of water

The amount of energy needed to raise the temperature of water, which is high due to hydrogen bonding, enabling water to act as a temperature buffer in living organisms.

Latent heat of vaporisation of water

The large amount of heat energy required to evaporate $1\,g$ of water, providing a cooling effect in organisms with minimal water loss.