Carbon Backbone, Isomers, Functional Groups, and Early Origins of Biomolecules

Vocabulary flashcards covering key concepts from the lecture: vitalism and abiotic synthesis, Miller-Urey, carbon backbone and valence, isomers, and seven functional groups (hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl) plus ATP and lipid context.

Vitalism

The belief that organic molecules could only be synthesized inside living organisms; disproven by lab synthesis (e.g., urea in 1828).

Abiotic synthesis

Formation of biological molecules from nonliving starting materials outside of living systems; demonstrated by Miller-Urey-type experiments.

Miller-Urey experiment

An experiment simulating early Earth conditions (water, methane, ammonia, hydrogen, with sparks) that produced amino acids and other organics.

Urea

One of the first organic molecules synthesized in the lab, showing biological molecules can be made abiotically.

Carbon backbone

The carbon skeleton that forms the core framework of most biological molecules.

Valence (two uses)

Valence can refer to the number of bonds an atom forms or to the electrons in its outer shell; two common biological meanings.

Four covalent bonds (carbon)

Carbon can form four covalent bonds, enabling diverse and complex organic structures.

Tetrahedral arrangement

Three-dimensional geometry around carbon when four single bonds are present, forming a tetrahedron.

Planar arrangement

Flat geometry around carbon when a double bond is present, as in carbon-carbon double bonds (sp2).

Hydrocarbon

A molecule consisting only of carbon and hydrogen; typically nonpolar and hydrophobic; backbone of many biomolecules.

Isomer

Compounds with the same molecular formula but different structures or arrangements.

Structural isomer

Isomers with the same formula but different connectivity of atoms.

Cis-trans isomer

A subset of structural isomers around a double bond; cis if substituents are on the same side, trans if opposite sides.

Enantiomer

Non-superimposable mirror-image isomers arising from chiral centers; often designated L/D or R/S and recognized by biological systems.

Racemic mixture

A 1:1 mixture of enantiomers; often produced in synthesis; usually only one enantiomer is biologically active.

Functional group

Specific atom groups attached to a carbon backbone that confer chemical properties and reactivity.

Hydroxyl group (-OH)

Polar group that enables hydrogen bonding and increases water solubility (alcohols).

Carbonyl group (C=O)

Carbon-oxygen double bond; two main classes are ketone (in the middle) and aldehyde (at the end); polar and reactive.

Carboxyl group (-COOH)

Carbonyl plus hydroxyl group; acts as an acid (can dissociate to -COO−) and increases solubility.

Amino group (-NH2)

Basic group that can accept hydrogen, become positively charged, and form ionic bonds.

Sulfhydryl group (-SH)

Sulfur analogue of hydroxyl; highly reactive; forms disulfide bonds (S–S) important for protein structure.

Phosphate group (-PO4^3-)

Phosphorus with multiple negative charges; provides polarity and high-energy bonds for energy transfer.

Methyl group (-CH3)

Nonpolar, hydrophobic group that can influence shape and packing and reduce water solubility.

ATP (adenosine triphosphate)

Cellular energy currency; three phosphate groups store energy; hydrolysis releases energy; cycles with ADP.

Fatty lipids as hydrocarbons

Fats are largely hydrocarbon chains; highly hydrophobic and energy-dense due to C–H bonds.