Biological Molecules and Their Functions

Flashcards covering key vocabulary related to biological molecules and their structures.

amino acid

The building blocks of proteins, containing an amino group, a carboxyl group, and a side chain (R group).

amphipathic

Molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.

carbohydrate

Organic compounds made of carbon, hydrogen, and oxygen, primarily used for energy and structure.

denaturation

The process in which proteins lose their structure and function due to external stress, such as temperature or pH changes.

disaccharide

A carbohydrate composed of two monosaccharides linked by a glycosidic bond.

ester bond

A bond formed between an alcohol and a carboxylic acid, characteristic of lipids.

globular protein

Proteins that are folded into compact, spherical shapes, often functional in nature.

glycosidic bond

A type of covalent bond that joins a carbohydrate (sugar) molecule to another group.

cohesion

The ability of molecules of the same substance to stick together, a property of water.

adhesion

The ability of dissimilar molecules to stick together, also a property of water.

surface tension

The cohesive force that causes the surface of a liquid to behave like a stretched elastic membrane.

capillary action

The ability of water to flow in narrow spaces against gravity, due to cohesion and adhesion.

high specific heat

The property of water that allows it to absorb large amounts of heat with little change in temperature.

evaporative cooling

The process through which the surface of an object becomes cooler during evaporation.

density of ice

Ice is less dense than liquid water, allowing it to float and providing insulation.

solvent

A substance that dissolves a solute, forming a solution.

hydrophilic

Substances that are attracted to water and can dissolve in it.

hydrophobic

Substances that repel water and do not dissolve in it.

enzyme

Biological catalysts that speed up chemical reactions in the body.

substrate

The reactant on which an enzyme works.

active site

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

enzyme-substrate complex

A temporary molecule formed when an enzyme comes into contact with its substrate.

product

The end result of an enzyme-catalyzed reaction.

activation energy

The minimum energy required for a chemical reaction to occur.

induced fit

The model describing how enzymes change shape slightly to fit the substrate better.

cofactor/coenzyme

Inorganic ions or organic molecules that assist in enzyme activity.

hydrogen bond

A weak bond formed between a hydrogen atom and an electronegative atom.

ion

An atom or molecule that has gained or lost one or more electrons, resulting in a charge.

lipid

A diverse group of hydrophobic macromolecules including fats, oils, and steroids.

macromolecule

Large, complex molecules, such as proteins, nucleic acids, carbohydrates, and lipids.

monomer

A small, basic molecular unit that can join with others to form a polymer.

monosaccharide

The simplest form of carbohydrates, consisting of a single sugar molecule.

nitrogen

An essential element that is a component of amino acids, nucleotides, and proteins.

non-polar molecule

Molecules that do not have distinct positive and negative ends and do not mix with water.

nucleic acid

Biomolecules, including DNA and RNA, responsible for storing and transferring genetic information.

nucleotide

The basic building block of nucleic acids, consisting of a sugar, phosphate group, and nitrogen base.

fatty acid

A carboxylic acid with a long aliphatic chain, which can be saturated or unsaturated, making up lipids.

triglyceride

A lipid made from glycerol and three fatty acids; used for storing energy.

phospholipid

A lipid composed of a phosphate group and two fatty acids, forming the cell membrane.

steroid

A type of lipid characterized by a carbon skeleton with four fused rings.

saturated fat

Fatty acids with no double bonds; typically solid at room temperature.

unsaturated fat

Fatty acids that have one or more double bonds; typically liquid at room temperature.

competitive inhibitor

A substance that competes with the substrate for binding to the active site of an enzyme.

noncompetitive inhibitor

A substance that binds to an enzyme at a location other than the active site, altering its function.

allosteric site

A site on an enzyme where a molecule can bind and affect enzyme activity.

optimal temperature/pH

The conditions in which an enzyme is most active.

organic molecule

A molecule that contains carbon and is part of living organisms.

peptide bond

The bond formed between two amino acids during protein synthesis.

polar molecule

A molecule with a distribution of charge leading to positive and negative ends.

polymer

A large molecule made up of repeated subunits (monomers).

protein

A macromolecule made up of amino acids that perform various functions in living organisms.

water

A vital molecule for life, known for its solvent properties and role in biochemical reactions.

starch

A polysaccharide that stores energy in plants.

glycogen

A polysaccharide that stores energy in animals.

cellulose

A polysaccharide that forms the structural component of plant cell walls.

chitin

A structural polysaccharide found in the exoskeleton of arthropods.

polypeptide

A chain of amino acids linked by peptide bonds.

primary structure

The unique sequence of amino acids in a protein.

secondary structure

The coiling or folding of a polypeptide into a specific shape, such as an alpha helix or beta sheet.

tertiary structure

The overall 3D shape of a polypeptide, determined by interactions among various side chains.

quaternary structure

The formation of a protein made of multiple polypeptide chains.

DNA

Deoxyribonucleic acid, the molecule that carries genetic information.

RNA

Ribonucleic acid, involved in protein synthesis and gene expression.

phosphate group

A functional group consisting of a phosphorus atom bonded to four oxygen atoms, part of nucleotides.

nitrogenous base

A component of nucleotides in nucleic acids; includes adenine (A), thymine (T), guanine (G), cytosine (C), and uracil (U).

sugar (ribose/deoxyribose)

A pentose sugar that forms part of the backbone of nucleic acids.

phosphodiester bond

The bond between phosphate group of one nucleotide and the sugar of another, forming the nucleic acid backbone.

base pairing

The specific pairing between nitrogenous bases in DNA (A with T, G with C) and in RNA (A with U, G with C).