Biology SP015 - Chapter 1 Molecules of Life

Water

A polar molecule consisting of one oxygen atom and two hydrogen atoms, responsible for unique properties such as being a universal solvent.

Hydrogen bond

Weak attraction between positively charged hydrogen atoms and negatively charged atoms, contributing to water's unique properties such as surface tension.

Covalent bond

A chemical bond formed by the sharing of electrons between two atoms.

Universal solvent

Water’s ability to dissolve most substances, including salts and sugars, due to its polarity.

Viscosity

A measure of a liquid’s internal resistance to flow; water is characterized by low viscosity.

Specific heat capacity

The amount of heat energy required to raise the temperature of 1g of a substance by 1ºC; water has a high specific heat capacity.

Latent heat of vaporization

The amount of energy needed to convert liquid water into vapor; water has a high latent heat of vaporization.

Surface tension

The strength of a liquid's surface film, which allows objects to float or insects to walk on water.

Density

Mass per unit volume; water reaches its maximum density at 4°C.

Monosaccharides

Simple sugars that are the building blocks of carbohydrates; examples include glucose and fructose.

Disaccharides

Carbohydrates formed by the condensation of two monosaccharides; examples include sucrose and lactose.

Polysaccharides

Complex carbohydrates made of long chains of monosaccharides; examples include starch, glycogen, and cellulose.

Triglycerides

Lipids formed by the ester linkage of three fatty acids to one glycerol molecule.

Phospholipids

Lipids consisting of two fatty acids attached to a glycerol and a phosphate group; key components of cell membranes.

Steroids

Lipids with a structure composed of four hydrocarbon rings; examples include cholesterol and testosterone.

Amino acids

The building blocks of proteins, containing an amino group, a carboxyl group, and a variable R group.

Peptide bond

A covalent bond formed between two amino acids during protein synthesis.

Primary structure of protein

The linear sequence of amino acids in a polypeptide chain.

Secondary structure of protein

The localized folding of a polypeptide into structures like alpha helices and beta sheets, stabilized by hydrogen bonds.

Quaternary structure of protein

The assembly of multiple polypeptide subunits into a single functional protein unit.

Nucleotide

The monomer unit of nucleic acids, made up of a pentose sugar, nitrogenous base, and phosphate group.

DNA

Deoxyribonucleic acid, a double-stranded molecule that contains hereditary information.

RNA

Ribonucleic acid, a single-stranded molecule involved in protein synthesis.

Base pairing

The specific hydrogen bonding between nitrogenous bases in DNA: adenine pairs with thymine, and cytosine pairs with guanine.

Polynucleotide

A polymer made of nucleotide monomers that forms the backbone of DNA and RNA.

Electrolyte

A substance that dissociates into ions when dissolved in water, allowing it to conduct electricity.

pH scale

A scale that measures the acidity or alkalinity of a solution, ranging from 0 to 14.

Homeostasis

The maintenance of a stable internal environment in an organism despite external changes.

Enzyme

A biological catalyst that speeds up a chemical reaction in living organisms.

Fermentation

A metabolic process that converts sugars to acids, gases, or alcohol in the absence of oxygen.

Osmosis

The movement of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Metabolism

The sum of all chemical reactions that occur within a living organism to maintain life.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, yielding energy in the form of ATP.

Photosynthesis

The process by which green plants convert light energy into chemical energy stored in glucose.

Cellular respiration

The process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

What is an atom?

The smallest unit of a chemical element, consisting of a nucleus surrounded by electrons.

What is a molecule?

Two or more atoms bonded together through covalent bonds.

What is a chemical reaction?

A process in which substances (reactants) are transformed into different substances (products) through breaking and forming bonds.

What is pH?

A measure of the acidity or alkalinity of a solution, typically ranging from 0 (acidic) to 14 (alkaline), with 7 being neutral.

What is an ion?

An atom or molecule that has a net electric charge due to the loss or gain of one or more electrons.

What is a macromolecule?

A large, complex molecule, typically composed of thousands of atoms, e.g., proteins, nucleic acids, and polysaccharides.

What is a catalyst?

A substance that increases the rate of a chemical reaction without being consumed or permanently altered in the process.

What is ATP?

Adenosine triphosphate, the primary energy carrier in cells, storing and transferring energy for various cellular processes.

What is chlorophyll?

A green pigment found in plants that is essential for photosynthesis, allowing plants to absorb light energy.

What is a substrate?

The reactant molecule upon which an enzyme acts during a biochemical reaction.