Biochemistry and Molecules of Life

Comprehensive vocabulary review flashcards covering atomic structure, chemical bonding, acids and bases, carbon chemistry, biomolecules, and enzyme action.

Organic Compound

A chemical compound that contains the element carbon bonded with hydrogen (e.g., glucose, $C_6H_{12}O_6$), contrasting with inorganic compounds such as $H_2O$ and $CO_2$.

Carbohydrates

A class of organic biomolecules composed of the elements $C$, $H$, and $O$ in a characteristic $1:2$ ratio ($C:H$) whose primary function is providing daily energy.

Monosaccharide

The monomer unit of carbohydrates (simple sugars such as glucose, galactose, and fructose) that share the same chemical formula ($C_6H_{12}O_6$) but possess different structures.

Polysaccharide

A carbohydrate polymer formed by chaining multiple sugar monomers together (e.g., starch).

Lipids

A class of organic biomolecules composed of $C$, $H$, and $O$ that store energy and compose the cell membrane; examples include fats, oils, and waxes.

Phospholipid

A specialized lipid that forms cell membranes, featuring one hydrophilic (water-loving) head and one hydrophobic (water-fearing) tail.

Saturated Fat

A type of fat in which each carbon atom is covalently bonded to four other atoms through single bonds; examples include animal fat and butter.

Unsaturated Fat

A type of fat in which carbon atoms are bonded to only three other atoms because at least one bond is a double bond; an example is vegetable oil.

Triglyceride

A lipid polymer constructed from one glycerol molecule bonded to three fatty acids via a condensation reaction.

Amino Acid

The monomer building block of proteins, composed of a central carbon bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable side chain ($R$ group).

Peptide Bond

A covalent bond formed between two amino acids through a condensation reaction, joining them into dipeptides and polypeptides.

Proteins

Biomolecules composed of $C$, $H$, $O$, and $N$ that function in cellular growth, maintenance, and acting as catalysts in living things.

Nucleic Acids

Biomolecules made of $C$, $H$, $O$, $N$, and $P$ whose function is to store and transmit genetic information; examples include DNA and RNA.

Nucleotide

The monomer unit of nucleic acids, consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Functional Groups

Clusters of atoms attached to carbon compounds that influence the chemical characteristics and properties of the molecules they compose.

Monomer

A small, simpler molecule that can bind with other identical or similar molecules to form larger carbon molecules called polymers.

Polymer

A long-chain molecule made up of a repeated pattern of bonded monomer units; very large polymers are termed macromolecules.

Condensation Reaction

A chemical reaction where monomers link together to form polymers, releasing a molecule of water ($H_2O$) as a byproduct.

Hydrolysis

A chemical reaction meaning 'water cutting-breaking' that breaks down polymers into monomers, using water ($H_2O$) as a required reactant.

Valence Electrons

Electrons residing in the outermost energy level of an atom that participate directly in chemical bonding.

Lewis Dot Diagram

A diagrammatic representation of an element showing its valence electrons as dots surrounding the chemical symbol.

Covalent Bond

A chemical bond formed when two nonmetal atoms share one or more pairs of electrons (e.g., $H_2$ or $HBr$).

Ionic Bond

The attractive force between oppositely charged ions, formed when electrons are completely transferred from one atom to another (e.g., $NaCl$).

Hydrogen Bond

The weak force of attraction between a hydrogen atom carrying a partial positive charge and another molecule carrying a partial or full negative charge.

Dissociation of Water

The self-ionization of water molecules into free hydrogen ions ($H^+$) and hydroxide ions ($OH^-$), represented by the equation $H_2O \rightarrow H^+ + OH^-$.

Hydronium Ion

The positive ion ($H_3O^+$) formed when a free hydrogen ion ($H^+$) reacts with another water molecule ($H_2O$).

Acid

A solution in which the concentration of hydrogen ions exceeds the concentration of hydroxide ions ($[H^+] > [OH^-]$), commonly possessing hydrogen protons.

Base

A solution (also known as alkaline) in which the concentration of hydroxide ions exceeds that of hydrogen ions ($[H^+] < [OH^-]$), commonly containing hydroxide.

pH Scale

A scale ranging from $0$ to $14$ used to measure the relative concentrations of $H^+$ and $OH^-$ ions, where each individual unit change reflects a tenfold ($10\times$) change in acidity or basicity.

Atom

The smallest unit of matter that cannot be broken down by chemical means, consisting of a central nucleus and orbiting electrons.

Element

A pure chemical substance composed of only one kind of atom.

Atomic Number

The number of positively charged protons located in the nucleus of an atom.

Mass Number

The atomic mass calculated by summing the total number of protons and neutrons in the nucleus of an atom.

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Isotopes

Variations of an element's atoms that maintain the same number of protons but have a different number of neutrons, changing the atomic mass.

Radioactive Isotope

An unstable isotope that spontaneously releases neutrons or radiation.

Enzyme

A specialized protein that acts as a biological catalyst to speed up chemical reactions by joining together or breaking apart substrates into products.

Active Site

The specific region on an enzyme where substrate molecules bind during a chemical reaction.

Enzyme-Substrate Complex

The temporary molecular intermediate formed when substrate molecules land and bind to an enzyme's active site.

Lock and Key Model

A structural model demonstrating enzyme specificity, where the enzyme acts as the lock and the substrate acts as the unique fitting key.

Activation Energy

The threshold energy required for a chemical reaction to occur, which enzymes lower to accelerate reaction rates.

Catalase

An enzyme found in the liver that catalyzes the breakdown of toxic hydrogen peroxide ($H_2O_2$) into oxygen gas ($O_2$) and water ($H_2O$).