SHS General Biology: Macromolecules, Bioenergetics, and Photosynthesis

Comprehensive vocabulary flashcards covering functional groups, macromolecule structures, protein folding levels, enzymatic digestion, redox bioenergetics, and photosynthetic pathways based on the General Biology review reviewer.

Hydroxyl Group

A polar functional group ($-\text{OH}$) that forms hydrogen bonds with water; it occurs biologically in carbohydrates, proteins, nucleic acids, and lipids.

Carbonyl Group

A polar functional group ($-\text{C=O}$) with oxygen double-bonded to carbon; found in nucleic acids and carbohydrates, classifying monosaccharides into aldoses or ketoses.

Carboxyl Group

An acidic functional group ($-\text{COOH}$) that donates a proton ($\text{H}^+$) in solution to become ionized as $-\text{COO}^-$; found in amino acids and fatty acids.

Amino Group

A basic functional group ($-\text{NH}_2$) that accepts a proton ($\text{H}^+$) in aqueous solution to become $-\text{NH}_3^+$; found in amino acids and nucleic acids.

Sulfhydryl Group

A functional group ($-\text{SH}$) present in cysteine amino acid residues that forms covalent disulfide bridges ($-\text{S}-\text{S}-$).

Phosphate Group

A negatively charged, highly reactive functional group ($-\text{PO}_4^{2-}$) found in the DNA/RNA backbone, ATP, and phospholipids.

Methyl Group

A nonpolar, hydrophobic hydrocarbon functional group ($-\text{CH}_3$) found in proteins and chemically modified DNA bases.

Dehydration Synthesis

An energy-requiring condensation reaction that links monomers into polymers by removing an $-\text{OH}$ group from one monomer and an $-\text{H}$ from another, releasing a water molecule ($\text{H}_2\text{O}$).

Hydrolysis Reaction

An energy-releasing cleavage reaction that breaks down polymers into monomers through the addition of a water molecule ($\text{H}_2\text{O}$).

Structural Isomers

Molecules that share an identical chemical formula (such as $\text{C}_6\text{H}_{12}\text{O}_6$ for glucose and fructose) but differ in the placement of atoms, such as the position of the carbonyl group.

Stereoisomers

Molecules sharing the same chemical formula and functional group positions but differing in the three-dimensional spatial orientation of groups, such as the $-\text{OH}$ and $-\text{H}$ orientation around C-4 in glucose versus galactose.

Amylose

An unbranched, plant energy storage polysaccharide consisting of $\alpha$-glucose linked by $\alpha\text{-}1,4$ glycosidic bonds that coils helically in water.

Amylopectin

A branched plant energy storage polysaccharide composed of $\alpha$-glucose units linked by $\alpha\text{-}1,4$ bonds with $\alpha\text{-}1,6$ branches occurring every $24\text{--}30$ glucose units.

Glycogen

A highly branched animal energy storage carbohydrate stored in liver and muscle cells, formed from $\alpha$-glucose with $\alpha\text{-}1,4$ linkages and frequent $\alpha\text{-}1,6$ branch points.

Cellulose

A structural polysaccharide made of straight, unbranched chains of $\beta$-glucose joined by $\beta\text{-}1,4$ linkages that form microfibril fibers within plant cell walls.

Chitin

A structural polysaccharide consisting of modified $\beta$-glucose units (N-acetylglucosamine) linked by $\beta\text{-}1,4$ bonds that cross-link with proteins to form fungal cell walls and arthropod exoskeletons.

Purines

Double-ring nitrogenous bases found in both DNA and RNA, specifically Adenine (A) and Guanine (G).

Pyrimidines

Single-ring nitrogenous bases, including Cytosine (C), Thymine (T, specific to DNA), and Uracil (U, specific to RNA and lacking a methyl group).

Phosphodiester Bond

A covalent linkage connecting the phosphate group on the $5'$ carbon of one nucleotide to the hydroxyl group on the $3'$ carbon of the adjacent pentose sugar.

Saturated Fatty Acids

Fatty acids containing no $\text{C=C}$ double bonds that are fully saturated with hydrogen, packing tightly together as solids at room temperature.

Unsaturated (Cis) Fatty Acids

Fatty acids with one or more $\text{C=C}$ double bonds in cis configuration (hydrogens on the same side), causing kinks that prevent tight packing and maintain a liquid oil state at room temperature.

Trans Fatty Acids

Artificially hydrogenated fatty acids with $\text{C=C}$ double bonds in trans configuration (hydrogens on opposite sides) that adopt straight-chain behavior and raise LDL cholesterol.

Amphipathic

A structural characteristic of molecules, like phospholipids, that possess both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Primary Structure

The linear sequence of amino acids in a polypeptide chain joined by covalent peptide bonds, which is resistant to mild changes in heat and pH.

Secondary Structure

Localized regular folding patterns (such as $\alpha$-helices and $\beta$-pleated sheets) maintained by hydrogen bonds between the polypeptide backbone's $\text{C=O}$ and $\text{N-H}$ groups.

Tertiary Structure

The overall three-dimensional globular shape of a single polypeptide chain stabilized by R-group interactions, including hydrophobic exclusion, ionic salt bridges, hydrogen bonds, and disulfide bridges.

Quaternary Structure

The multi-subunit spatial arrangement formed by the aggregation of two or more polypeptide chains joined through hydrophobic interactions and nonpolar interfaces.

Denaturation

The unfolding of a protein and complete loss of its biological function resulting from environmental disruptions (heat, pH, ionic shifts) that break weak stabilizing bonds.

Catabolic Pathways

Exergonic metabolic processes ($-\Delta G$) that break down complex molecules into simpler units via hydrolysis, releasing stored free energy.

Anabolic Pathways

Endergonic metabolic processes ($+\Delta G$) that consume ATP to assemble complex macromolecules from simpler precursor molecules via dehydration synthesis.

Oxidation

A bioenergetic chemical process defined as the loss of electrons, loss of hydrogen, or gain of oxygen, resulting in a loss of stored chemical energy.

Reduction

A bioenergetic chemical process defined as the gain of electrons, gain of hydrogen, or loss of oxygen, resulting in a net gain of stored chemical energy.

Chylomicrons

Lipoprotein aggregates formed inside enterocytes from triglycerides, cholesterol, proteins, and phospholipids that enter lymphatic capillaries (lacteals) for bodily transport.

Photolysis of Water

The light-driven enzymatic cleavage of water ($2\text{H}_2\text{O} \rightarrow \text{O}_2 + 4\text{H}^+ + 4e^-$) in Photosystem II that replaces oxidized reaction center electrons and releases oxygen.

Rubisco

The primary carbon-fixing enzyme in the Calvin Cycle that catalyzes the attachment of inorganic $\text{CO}_2$ to ribulose 1,5-bisphosphate (RuBP).

C4 Pathway

A photosynthetic adaptation achieving spatial separation of carbon fixation in mesophyll cells (via PEP Carboxylase) and the Calvin cycle in bundle-sheath cells to avoid photorespiration.

CAM Pathway

A photosynthetic adaptation in arid-zone plants providing temporal separation by capturing $\text{CO}_2$ with PEP Carboxylase at night and executing the Calvin cycle during daylight.