The Chemical Building Blocks of Life: Carbon and Macromolecules

Comprehensive vocabulary flashcards covering the chemical foundations of life, carbon chemistry, functional groups, macromolecule structures and functions, and enzyme kinetics from Chapter 4 and Chapter 5.

Organic Chemistry

The branch of chemistry that specializes in the study of carbon compounds.

Tetravalence

The property of carbon having $4$ valence electrons, enabling it to form up to $4$ covalent bonds.

CHNOPS

An acronym representing the major chemical elements of life: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

Isomers

Molecules that share the same molecular formula but have different atomic arrangements and distinct chemical properties.

Structural Isomers

Molecules with identical molecular formulas that vary in their covalent arrangements and connectivity.

Stereoisomers

Molecules that have the same molecular formula and identical covalent connectivity, but differ in their spatial arrangement.

Cis-Trans Isomers

Isomers differing in spatial arrangement around a double bond; functional groups are on the same side in cis isomers and on opposite sides in trans isomers.

Enantiomers

Molecules that are non-superimposable mirror images of each other.

Thalidomide

A drug whose effective enantiomer reduces morning sickness, but whose ineffective enantiomer causes birth defects due to in vivo conversion.

Functional Groups

Specific configurations of atoms attached to carbon skeletons that dictate the chemical behavior and properties of organic molecules.

Hydroxyl Group

A chemical functional group ($-\text{OH}$) characteristic of alcohols, found in carbohydrates, proteins, nucleic acids, and lipids.

Carbonyl Group

A functional group consisting of a carbon atom linked by a double bond to an oxygen atom ($>\text{C}=\text{O}$), found in ketones and aldehydes.

Carboxyl Group

An acidic functional group ($-\text{COOH}$) that can donate a hydrogen ion to form an ionized carboxylate ($-\text{COO}^-$), found in organic acids, proteins, and lipids.

Amino Group

A basic functional group ($-\text{NH}_2$) that can accept a proton to form an ionized amine ($-\text{NH}_3^+$), found in amino acids and nucleic acids.

Sulfhydryl Group

A functional group ($-\text{SH}$) characteristic of thiols like cysteine, capable of forming stabilizing cross-links in proteins.

Phosphate Group

A negatively charged functional group ($-\text{OPO}_3^{2-}$) that is key to nucleic acid backbones and cellular energy transfers.

Methyl Group

A nonpolar functional group ($-\text{CH}_3$) found in amino acids and methylated nucleic acid bases such as $5\text{-methylcytosine}$.

Monomer

A single molecular subunit that serves as the repeating building block of a polymer.

Polymer

A large molecule composed of many identical or similar repeating subunits (monomers) linked together by covalent bonds.

Dehydration Synthesis

An anabolic, endothermic reaction requiring energy and enzymes that covalently connects monomers into larger molecules through the loss of water.

Hydrolysis

A catabolic, exothermic chemical reaction that breaks the covalent bonds between monomers in a polymer through the addition of water.

Carbon Fixation

Metabolic reactions that convert inorganic, gaseous carbon ($\text{CO}_2$) into non-gaseous organic compounds like sugars.

Monosaccharide

The simplest carbohydrate monomer, exhibiting an empirical formula of $(\text{CH}_2\text{O})_n$ and bearing a carbonyl group along with multiple hydroxyl groups.

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration synthesis reaction.

Starch

A plant storage polysaccharide consisting of amylose and amylopectin, built from glucose monomers joined by $\alpha$-linkages.

Glycogen

An extensively branched storage polysaccharide of glucose found in animal tissues.

Cellulose

A structural plant polysaccharide composed of glucose monomers connected by $\beta\text{-}1,4$ glycosidic linkages that forms microfibrils in cell walls.

Chitin

A modified structural polysaccharide found in fungal cell walls, arthropod exoskeletons, and dissolving surgical stitches.

Peptidoglycan

A modified structural polysaccharide containing amino acids that forms the cell wall of bacteria.

Ruminants

Herbivores with an expanded upper gastrointestinal tract that utilize symbiotic bacteria and regurgitation of cud to digest cellulose.

Caecophores

Herbivores (such as rabbits) with an expanded lower gastrointestinal tract that use microorganisms to break down cellulose without regurgitating food.

Nucleotide

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

Phosphodiester Bond

The covalent bond linking the $3'$ carbon of one nucleotide's sugar to the $5'$ phosphate of an adjacent nucleotide.

Purines

Double-ring nitrogenous bases found in nucleic acids, specifically adenine and guanine.

Pyrimidines

Single-ring nitrogenous bases found in nucleic acids, specifically cytosine, thymine (DNA only), and uracil (RNA only).

Adenosine Triphosphate (ATP)

A nucleotide composed of ribose, adenine, and three phosphate groups that serves as the primary chemical energy currency of the cell.

Primary Structure

The unique, linear sequence of amino acids in a polypeptide chain joined by peptide bonds.

Secondary Structure

Localized coilings ($\alpha$-helix) or folds ($\beta$-pleated sheet) in a polypeptide chain stabilized by hydrogen bonds between peptide backbone atoms.

Tertiary Structure

The overall three-dimensional folding of a single polypeptide chain determined by interactions among R groups, including hydrogen bonds, ionic bonds, hydrophobic exclusion, and disulfide bridges.

Quaternary Structure

The functional structural organization that results when two or more polypeptide chains aggregate into a multi-subunit protein.

Chaperone Proteins

Specialized proteins that assist in the proper folding and conformational maturation of newly synthesized polypeptides.

Protein Motifs

Common recurring combinations of secondary structure elements found in many different polypeptides, such as the $\beta\text{-}\beta$ or helix-turn-helix motif.

Protein Domains

Distinct, functional, modular structural regions within a single polypeptide chain.

Denaturation

The loss of a protein's native three-dimensional conformation and function caused by extreme changes in pH, temperature, or salt concentration.

Oligosaccharides

Short chains of monosaccharides covalently linked to membrane proteins to form glycoproteins that function in cell recognition and signaling.

Triglycerides

Simple lipids consisting of one glycerol molecule linked to three fatty acids that store energy at approximately $9\,\text{calories/gram}$.

Saturated Fatty Acid

A hydrocarbon chain containing no carbon-carbon double bonds, maximizing attached hydrogens; typically solid at room temperature.

Unsaturated Fatty Acid

A hydrocarbon chain possessing one or more double bonds that cause bending; typically liquid at room temperature.

Phospholipid

An amphipathic molecule composed of one glycerol, two hydrophobic fatty acid tails, and a hydrophilic phosphate head that forms biological membranes.

Steroids

Lipids characterized by a four-ring perhydrocyclopentanophenanthrene carbon skeleton containing $17$ core carbons.

Cholesterol

The most abundant steroid in the human body; comprises about $10\%$ of dry brain weight and serves as the biosimilar starting point for all other body steroids.

Bile Acids

Steroid derivatives with polar and nonpolar ends that act as emulsifying agents in the digestion of fats.

Active Site

The specific region of an enzyme that binds the substrate and provides the catalytic environment for the reaction.

Induced Fit

The conformational change undergone by an enzyme upon substrate binding that creates a tighter, more catalytically active fit.

Ribozymes

Non-protein RNA molecules that possess intrinsic enzymatic catalytic activity, such as the ribosome.

Competitive Inhibitor

A regulatory molecule that binds directly to an enzyme's active site, competing with the substrate to decrease catalytic activity.

Noncompetitive Inhibitor

An inhibitor that binds to an allosteric site rather than the active site, inducing a conformational change that prevents substrate binding or reaction.

Allosteric Site

A specific receptor site on an enzyme separate from the active site where activator or inhibitor molecules bind to regulate activity.

Ketones

Organic compounds containing a carbonyl group bonded to two carbons within the interior of a carbon chain.

Aldehydes

Organic compounds containing a carbonyl group bonded to at least one hydrogen atom located at the terminus of a carbon chain.