Carbon and the Molecular Diversity of Life

Vocabulary flashcards covering core concepts from carbon chemistry, functional groups, isomerism, key energy molecules, and origin-of-life experiments mentioned in the notes.

Carbon skeleton

The carbon backbone of organic molecules—the chain or ring of carbon atoms that forms the structural framework.

Valence (of carbon)

The bonding capacity of an atom; carbon has valence 4, allowing it to form four covalent bonds.

Tetrahedral geometry

The 3D arrangement around a carbon atom with four single bonds, forming a tetrahedral shape.

Hydrocarbon

A molecule composed only of carbon and hydrogen.

Alkane

A saturated hydrocarbon with only single bonds; generally {CnH2n+2}. Example: ethane, propane.

Alkene

An unsaturated hydrocarbon with at least one carbon–carbon double bond; more reactive than alkanes. Example: 1-butene, 2-butene.

Isomer

Compounds with the same molecular formula but different covalent arrangements of atoms.

Structural isomer

Isomers that have the same formula but different covalent bonding patterns and atom-to-atom connections.

Geometric (cis-trans) isomer

Isomers around a double bond that differ in spatial arrangement; cis (same side) vs. trans (opposite sides).

Trans isomer

A geometric isomer where substituents are on opposite sides of a double bond.

Cycloalkane

A cyclic hydrocarbon (ring structure); cyclohexane is a common example.

Methyl group

A CH3 substituent; a small, nonpolar functional unit often found in organic molecules.

Enantiomer

A non-superimposable mirror-image isomer; can have very different biological effects (e.g., certain drug enantiomers).

Functional group

A reactive group of atoms within a molecule that largely determines its properties and reactivity.

Hydroxyl group (OH)

An oxygen–hydrogen group; polar; found in alcohols and carbohydrates.

Carbonyl group (C=O)

A carbon atom double-bonded to oxygen; found in aldehydes and ketones.

Aldehyde

A carbonyl group at the end of a carbon skeleton.

Ketone

A carbonyl group within the carbon skeleton.

Carboxyl group (COOH)

An acidic functional group found in organic acids and amino acids.

Amino group (NH2)

A basic functional group important in amino acids and proteins.

Sulfhydryl group (SH)

A thiol group; can form disulfide bonds and influence protein structure.

Phosphate group (PO4)

A functional group essential for energy transfer (ATP) and nucleic acids.

ATP (adenosine triphosphate)

The cell’s energy currency; an adenosine molecule bonded to three phosphate groups.

Adenosine

Adenine attached to ribose; a component of RNA and part of ATP.

Ribose

A five-carbon sugar found in RNA.

Adenine

A purine base found in DNA, RNA, and ATP.

Glycine

The simplest amino acid; produced in some prebiotic experiments like Miller–Urey; nonessential in humans.

Miller–Urey experiment

Experiment simulating early Earth conditions that showed abiotic synthesis of organic molecules (e.g., amino acids) using methane, ammonia, hydrogen, water, and electric discharge.

Abiotic synthesis

Non-biological chemical synthesis of organic molecules; a proposed step in the origin of life.

Early Earth’s atmosphere (in experiments)

Reducing mixture often cited as CH4, NH3, H2O, H2 to facilitate organic synthesis.

Formaldehyde

A simple aldehyde produced in prebiotic experiments; used as a building block for sugars and amino acids.

Hydrogen cyanide (HCN)

A toxic molecule produced in prebiotic experiments; a potential precursor to amino acids and nucleotides.

Urea

A simple organic compound observed in some prebiotic simulations.

Thalidomide (enantiomer concept)

A drug with enantiomers; one enantiomer caused birth defects, illustrating the importance of chirality in biology.

DNA methylation (methylation)

Addition of methyl groups to DNA; an epigenetic modification that can influence chromatin structure and gene expression.