Chapter 2: The Molecules of Life - Vocabulary Flashcards

Vocabulary practice flashcards covering atoms, chemical bonds, water chemistry, functional groups, biological macromolecules, and pre-biotic chemical principles from Chapter 2.

Atomic Number

The number of protons in an atom's nucleus, which uniquely specifies the chemical element.

Atomic Mass

The total number of protons plus neutrons contained within an atom's nucleus.

Isotope

Atoms of the same element that have the same atomic number of protons but differ in their total number of neutrons.

Covalent Bond

A chemical bond formed when two atoms share electrons in a shared molecular orbital to achieve stability.

Polar Covalent Bond

A covalent bond formed when shared electrons are unequally distributed due to differences in electronegativity, creating partial positive and partial negative charges.

Nonpolar Covalent Bond

A chemical bond formed when two atoms with identical or very similar electronegativities share electrons equally.

Ionic Bond

A chemical interaction formed by electrostatic attraction between oppositely charged ions created when one atom transfers an electron to another.

Hydrogen Bond

A weak interaction between the partial positive charge of a hydrogen atom covalently bonded to an electronegative atom and a partial negative charge on another electronegative atom.

Van der Waals Forces

Weak electrostatic attractions between atoms or nonpolar molecules caused by temporary, short-lived charge asymmetries created by moving electrons.

Hydrophilic

Describing polar molecules that interact favorably with and readily dissolve in water.

Hydrophobic

Describing nonpolar molecules that do not interact favorably with water and tend to aggregate away from aqueous solutions.

pH Scale

A measure of the concentration of free protons ($H^+$) in a solution, determining its acidity or basicity.

Organic Molecules

Carbon-containing molecules that form the foundational structures and chemical basis of living organisms.

Isomers

Molecules that share the same chemical formula but differ in their structural arrangement of atoms, resulting in distinct functional properties.

Hydroxyl Group

A polar functional group ($-OH$) composed of a hydrogen atom single-bonded to an oxygen atom; highly water-soluble and neutral in pH.

Carbonyl Group

A polar and reactive functional group ($>C=O$) composed of a carbon atom double-bonded to an oxygen atom, found in aldehydes and ketones.

Amino Group

A functional group ($-NH_2$) featuring a nitrogen atom bonded to two hydrogen atoms that acts as a base by accepting a proton to gain a positive charge ($+1$).

Phosphate Group

An acidic functional group ($-OPO_3^{2-}$) containing a central phosphorus atom bonded to four oxygen atoms; carries a negative charge and releases energy when reacting with water.

Methyl Group

A nonpolar and hydrophobic functional group ($-CH_3$) consisting of a carbon atom bonded to three hydrogen atoms that often functions as a biological marker.

Amino Acid

The monomer subunit of proteins consisting of a central $\alpha$ carbon attached to an amino group, a carboxyl group, a hydrogen atom, and a variable R group.

Peptide Bond

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

Nucleotide

The monomer building block of nucleic acids, consisting of a 5-carbon sugar, a nitrogen-containing base, and one or more phosphate groups.

Pyrimidines

A category of single-ring nitrogenous bases found in nucleic acids, including cytosine, thymine, and uracil.

Purines

A category of double-ring nitrogenous bases found in nucleic acids, including adenine and guanine.

Phosphodiester Bond

A strong covalent bond linking the phosphate group of one nucleotide to the $3'$ hydroxyl group ($-OH$) of an adjacent nucleotide in a nucleic acid strand.

Monosaccharide

The basic monomer unit of carbohydrates, consisting of simple sugar molecules such as glucose, galactose, or fructose.

Glycosidic Bond

A covalent bond linking monosaccharide units together to form complex carbohydrates like disaccharides or polysaccharides.

Fatty Acid

A lipid molecule comprised of a long hydrocarbon chain joined to a carboxyl group at one end.

Saturated Fatty Acid

A fatty acid chain with no carbon-carbon double bonds, maximizing hydrogen atoms and allowing tight packing that remains solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain containing one or more carbon-carbon double bonds, creating kinks in the chain structure that lower its melting point.

Triacylglycerol

An uncharged, hydrophobic lipid formed by attaching three fatty acid chains to a glycerol backbone, used for long-term energy storage.

Steroid

A class of lipids characterized by a structure of four fused carbon rings, such as cholesterol and certain steroid hormones.

Prebiotic Synthesis Experiment

An experimental apparatus demonstrating that biological building blocks can synthesize spontaneously from simple gases ($H_2O$, $CH_4$, $NH_3$, $H_2$) exposed to electrical energy.