Basics of Biological Sciences - Synthesis of Macromolecules

Vocabulary flashcards covering the key terms, chemical structures, classification schemes, and functions of biological macromolecules based on Chapter 3 lecture material.

Biological Macromolecules

Large organic, carbon-containing molecules built from smaller organic units that comprise most of a cell's dry mass, including carbohydrates, lipids, proteins, and nucleic acids.

Dehydration Synthesis

A covalent bonding process where monomers join to form polymers and release a water molecule ($\text{H}_2\text{O}$); an endergonic (energy-requiring) reaction catalyzed by specific enzymes.

Hydrolysis

A chemical reaction that breaks polymers down into monomers using water, where one monomer gains a hydrogen atom ($\text{H}^+$) and the other gains a hydroxyl group ($\text{OH}^-$); an exergonic (energy-releasing) reaction.

Carbohydrates

Biological macromolecules with a carbon to hydrogen to oxygen stoichiometric ratio of $1:2:1$ represented by the formula $\text{(CH}_2\text{O)}_n$, serving as energy sources and structural components.

Monosaccharides

Simple sugars containing three to seven carbon atoms with names ending in "-ose" (e.g., glucose) that exist in equilibrium between linear and ring forms in aqueous solutions.

Aldose

A monosaccharide that contains an aldehyde group ($\text{R-CH=O}$) at the end of its carbon chain.

Ketose

A monosaccharide that contains a ketone group ($\text{RC(=O)R'}$) within its carbon backbone.

Isomers

Molecules that share the same chemical formula (such as glucose, galactose, and fructose, which are all $\text{C}_6\text{H}_{12}\text{O}_6$) but possess different structural arrangements of functional groups.

Glycosidic Bond

A covalent bond formed between two monosaccharides through a dehydration synthesis reaction, which can be in an $\alpha$ or $\beta$ position depending on carbon-1 hydroxyl orientation.

Disaccharides

Sugar molecules formed when two monosaccharides are linked by a glycosidic bond; examples include lactose (glucose + galactose), maltose (glucose + glucose), and sucrose (glucose + fructose).

Starch

A plant storage polysaccharide made of glucose monomers linked by $\alpha\text{ }1\text{-}4$ or $\alpha\text{ }1\text{-}6$ glycosidic bonds, composed of unbranched amylose and branched amylopectin.

Glycogen

A highly branched glucose storage polysaccharide in animal cells, broken down via glycogenolysis to release glucose into the bloodstream when needed.

Cellulose

The most abundant biopolymer, consisting of unbranched glucose chains linked by $\beta\text{ }1\text{-}4$ glycosidic linkages, providing structural rigidity to plant cell walls.

Chitin

A nitrogen-containing polysaccharide made of repeating N-acetyl-b-d-glucosamine (NAG) units that forms the exoskeletons of arthropods and fungal cell walls.

Lipids

Nonpolar, hydrophobic macromolecules consisting mostly of hydrocarbon chains that function in energy storage, insulation, structural cell components, and hormone synthesis.

Triacylglycerols

Fat molecules composed of three fatty acid chains attached to a three-carbon glycerol backbone via ester bonds, synthesized by dehydration reactions releasing three $\text{H}_2\text{O}$ molecules.

Saturated Fatty Acid

A fatty acid chain with only single carbon-carbon bonds, fully saturated with hydrogen atoms, allowing tight packing that makes it solid at room temperature (e.g., stearic acid).

Unsaturated Fatty Acid

A fatty acid chain containing one or more double bonds between carbon atoms, creating kinks that prevent tight packing and keep it liquid at room temperature (e.g., oleic acid).

Trans Fats

Artificially hydrogenated oils with trans double-bond configurations that do not naturally occur, linked to elevated low-density lipoprotein (LDL) or "bad" cholesterol levels.

Omega-3 Fatty Acids

Essential polyunsaturated fatty acids with a double bond connecting the 3rd and 4th carbons from the omega end (e.g., ALA, EPA, DHA) that reduce heart disease risk and inflammation.

Waxes

Lipids made of long fatty acid chains esterified to long-chain alcohols that form protective hydrophobic coatings on aquatic bird feathers and plant leaf surfaces.

Phospholipids

Amphipathic molecules composed of two hydrophobic fatty acid chains and a hydrophilic modified phosphate head group attached to a glycerol or sphingosine backbone.

Steroids

Hydrophobic, nonpolar lipids characterized by a core structure of four fused hydrocarbon rings, such as cholesterol, cortisol, estrogen, and testosterone.

Cholesterol

The primary steroid sterol synthesized by the liver, acting as a precursor for steroid hormones, vitamin D, and bile salts, and serving as a structural component of plasma membrane lipid bilayers.

Amino Acids

The 20 distinct monomer building blocks of proteins, each containing a central carbon bonded to an amino group ($\text{NH}_2$), a carboxyl group ($\text{COOH}$), a hydrogen atom, and a unique variable side chain ($\text{R}$ group).

Peptide Bond

The covalent bond that links the carboxyl group of one amino acid to the amino group of another through a dehydration synthesis reaction.

Cytochrome c

An essential electron transport chain protein containing an iron ($\text{Fe}$)-bearing heme group that undergoes reversible reduction and oxidation, showing highly conserved amino acid homology across species.

Primary Protein Structure

The specific, linear sequence of amino acids linked together in a polypeptide chain.

Sickle Cell Anemia

A genetic disease resulting from a single amino acid substitution in the $147$-residue hemoglobin $\beta$ chain, replacing glutamate at position 7 with valine.

Secondary Protein Structure

Local folding patterns of a polypeptide backbone stabilized by hydrogen bonds, most commonly taking the form of an $\alpha\text{-helix}$ ($3.6$ residues per turn) or $\beta\text{-pleated sheet}$.

Tertiary Protein Structure

The overall three-dimensional shape of a single polypeptide chain created by $\text{R}$ group interactions, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.

Quaternary Protein Structure

The overall structural arrangement formed when multiple individual polypeptide subunits combine through weak interactions, hydrogen bonds, or disulfide bridges (e.g., insulin, hemoglobin).

Denaturation

The loss of a protein's three-dimensional shape and biological function caused by changes in temperature, pH, or exposure to chemicals, without breaking its primary amino acid sequence.

Chaperone Proteins

Specialized proteins (such as Heat Shock Protein 70 / HSP70) that assist and protect target proteins during folding under cellular stress.

Nucleic Acids

Biological macromolecules (DNA and RNA) composed of nucleotide monomer chains that store, carry, and express genetic instructions for cellular activity.

Nucleotide

The monomer unit of nucleic acids, consisting of a pentose sugar (ribose or deoxyribose), a nitrogenous base attached at the $1'$ carbon, and one or more phosphate groups attached at the $5'$ carbon.

Purines

Double-ring nitrogenous bases found in DNA and RNA, specifically adenine (A) and guanine (G).

Pyrimidines

Single-ring nitrogenous bases found in nucleic acids, consisting of cytosine (C), thymine (T, found in DNA), and uracil (U, found in RNA).

Phosphodiester Bond

The covalent linkage formed between the $5'$ phosphate group of an incoming nucleotide and the $3'$ hydroxyl group of the growing pentose sugar chain in nucleic acids.

MicroRNA

Small non-coding RNA molecules that regulate gene expression by binding to target messenger RNAs (mRNAs) and blocking their translation into proteins.