Carbon and the Molecular Diversity of Life

Flashcards testing vocabulary terms, structural definitions, and functional groups covered in the AP Biology lecture notes on carbon and molecular diversity.

Carbon

The sixth element of the periodic table and second most abundant element on Earth, capable of forming up to four covalent bonds to construct complex biological molecules.

Organic Carbon Molecules

Molecules associated with life that contain carbon covalently bonded to hydrogen, such as carbohydrates, proteins, lipids, and nucleic acids.

Inorganic Carbon Compounds

Carbon-containing compounds that do not contain carbon-hydrogen bonds, including carbon dioxide ($CO_2$), carbon monoxide ($CO$), carbonates, bicarbonates, and cyanide.

Hydrocarbons

Organic molecules consisting exclusively of carbon and hydrogen atoms, which form non-polar, hydrophobic backbones of biological macromolecules.

Structural Isomerism

A phenomenon where molecules share the same chemical formula but have different structural arrangements, such as butane ($C_4H_{10}$) and iso-butane.

Functional Groups

Chemically reactive groups of atoms that replace hydrogen atoms on a hydrocarbon backbone, imparting unique chemical properties and increasing solubility in water.

Hydroxyl Group ($-OH$)

A polar functional group where an oxygen atom is bonded to the carbon skeleton and a hydrogen atom, forming organic compounds known as alcohols.

Carbonyl Group ($=O$)

A functional group in which a carbon atom within a hydrocarbon is double-bonded to an oxygen atom, forming either aldehydes or ketones.

Aldehyde

A type of carbonyl-containing molecule in which the $=O$ group is located specifically at the end of the carbon chain, such as butanal.

Ketone

A type of carbonyl-containing molecule in which the $=O$ group is located within the interior of the carbon chain, such as butanone.

Carboxyl Group ($-COOH$)

An acidic functional group consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group, which can donate $H^+$ ions.

Carboxylic Acids

Organic molecules containing a carboxyl group ($-COOH$) that act as acids due to the dissociation and release of hydrogen ions ($H^+$).

Amino Group ($-NH_2$)

A functional group consisting of a nitrogen atom bonded to two hydrogen atoms, which acts as a base by picking up $H^+$ ions from solution to become $-NH_3^+$.

Amines

Organic compounds that contain an amino group ($-NH_2$).

Amino Acids

The building blocks of proteins, each containing both an amino group ($-NH_2$) and a carboxyl group ($-COOH$) attached to a central carbon with a variable $R$ group.

Sulfhydryl Group ($-SH$)

A functional group consisting of a sulfur atom bonded to a carbon skeleton and a hydrogen atom, which can form disulfide bridges to stabilize protein structure.

Disulfide Bridge

A covalent bond formed between two sulfhydryl groups ($-SH$) that stabilizes the three-dimensional tertiary or quaternary structure of proteins.

Phosphate Group ($PO_4^{2-}$)

A charged, polar functional group consisting of a phosphorus atom bonded to four oxygen atoms, used to transfer energy between biological molecules.

Adenosine Triphosphate (ATP)

The primary energy-transferring molecule found in living cells.

Carbon Dioxide ($CO_2$)

An inorganic carbon compound that serves as the ultimate source of carbon for all organic molecules in organisms, fixed via photosynthesis.