Carbon and the Molecular Diversity of Life Flashcards

Vocabulary practice flashcards covering carbon bonding, functional groups, reactions, carbohydrates, and lipids based on Chapter 3 study material.

Structural isomers

Molecules that share the same molecular formula but differ in the covalent arrangement or branching of their atoms.

Cis-trans isomers

Molecules that have the same covalent bonds but differ in their spatial arrangement around a double bond.

Enantiomers

Molecules that are mirror images of each other around an asymmetric carbon atom.

Hydroxyl group

A polar functional group ($-\text{OH}$) that forms hydrogen bonds with water, increasing the solubility of organic molecules like sugars and alcohols.

Carbonyl group

A polar functional group ($\text{C}=\text{O}$) found at the end of a carbon chain as an aldehyde or in the middle as a ketone, defining sugars as aldoses or ketoses.

Carboxyl group

A polar functional group ($-\text{COOH}$) that acts as an acid by donating an $\text{H}^+$ ion; found in amino acids and fatty acids.

Amino group

A polar functional group ($-\text{NH}_2$) that acts as a base by accepting an $\text{H}^+$ ion, acquiring a positive charge ($-\text{NH}_3^+$) inside cells.

Sulfhydryl group

A polar functional group ($-\text{SH}$) where two groups can react to form a covalent disulfide bond ($\text{S}-\text{S}$), helping to stabilize protein 3D structure.

Phosphate group

A polar, negatively charged functional group ($-\text{PO}_4$) that stores and transfers energy in ATP, forms part of the nucleic acid backbone, and forms the polar head of phospholipids.

Methyl group

A nonpolar, hydrophobic functional group ($-\text{CH}_3$) involved in gene regulation where adding it to DNA ("DNA methylation") can silence gene expression.

Dehydration reaction

A chemical reaction (also called condensation) that joins two monomers into a polymer by releasing a water molecule ($\text{monomer} + \text{monomer} \rightarrow \text{polymer} + \text{H}_2\text{O}$).

Hydrolysis reaction

A chemical reaction that breaks a covalent bond between two monomers in a polymer by adding a water molecule ($\text{polymer} + \text{H}_2\text{O} \rightarrow \text{monomer} + \text{monomer}$).

Polymer Hydrolysis Water Requirement Rule

The numerical relationship stating that completely hydrolyzing a polymer chain composed of $n$ monomers into individual monomers requires $n - 1$ water molecules.

Monosaccharide

A single sugar unit, such as glucose, which serves as the monomer building block for carbohydrates.

Disaccharide

A sugar molecule consisting of two monosaccharides joined together by a glycosidic linkage, such as lactose.

Polysaccharide

A carbohydrate polymer composed of many monosaccharides joined by glycosidic linkages, such as starch, glycogen, or cellulose.

Starch

A lightly branched or unbranched plant storage polysaccharide composed entirely of glucose monomers linked by $\alpha$ glycosidic linkages.

Glycogen

A highly branched animal storage polysaccharide made of glucose monomers joined by $\alpha$ glycosidic linkages, stored mainly in liver and muscle cells.

Cellulose

An unbranched structural polysaccharide in plant cell walls made of glucose monomers joined by $\beta$ glycosidic linkages that humans cannot digest.

Saturated fatty acid

A fatty acid chain containing no double bonds between carbon atoms and maximum hydrogen content, which is solid at room temperature and typically found in animal fats.

Unsaturated fatty acid

A fatty acid chain containing one or more double bonds and fewer hydrogen atoms, which is liquid at room temperature and typically found in plant oils.

Amphipathic

The property of a molecule having both a hydrophilic (polar) region and a hydrophobic (nonpolar) region.

Phospholipid

An amphipathic lipid made of glycerol attached to two fatty acid tails and a polar phosphate head, forming cell membrane bilayers.

Steroid

A lipid characterized by a carbon skeleton composed of four fused rings, classified as a lipid because of its nonpolar $\text{C}-\text{C}$ and $\text{C}-\text{H}$ bonds.

Triacylglycerol

A fat molecule composed of one glycerol molecule linked to three fatty acids.