DAT Biology – Cell & Molecular High-Yield Vocabulary

Comprehensive vocabulary deck covering chemical bonds, water properties, macromolecules, cell structures, bioenergetics, enzymes, metabolism, photosynthesis, and cell division—key high-yield terms for DAT Cell & Molecular Biology review.

Atom

Basic unit of matter composed of protons, neutrons, and electrons.

Molecule

Group of two or more atoms held together by chemical bonds.

Electronegativity

Atom’s ability to attract shared electrons within a bond.

Ionic Bond

Complete transfer of electrons between atoms with very different electronegativities, producing ions.

Covalent Bond

Bond formed by sharing electrons between atoms with similar electronegativities.

Non-polar Covalent Bond

Covalent bond with equal sharing of electrons due to identical or very similar electronegativities.

Polar Covalent Bond

Covalent bond with unequal sharing of electrons, creating a dipole.

Dipole

Separation of charge in a molecule due to unequal electron distribution.

Hydrogen Bond

Weak attraction between a hydrogen covalently bound to F, O, or N and another F, O, or N.

Van der Waals Interaction

Weak, temporary attraction caused by transient electron distribution in nearby molecules.

Hydration Shell

Layer of water molecules surrounding a dissolved ion or polar molecule.

Heat Capacity (of water)

Amount of heat required to raise water’s temperature; high due to extensive H-bonding.

Cohesion

Attraction between like molecules; water’s cohesion creates high surface tension.

Adhesion

Attraction between unlike substances, enabling capillary action.

Capillary Action

Movement of liquid through narrow spaces without external force, driven by adhesion and cohesion.

Mineral

Inorganic ion such as Ca2+ or K+ required for physiological functions.

Vitamin

Organic micronutrient required in small amounts; classified as fat-soluble or water-soluble.

Fat-Soluble Vitamin

Vitamin A, D, E, or K; stored in body fat and can accumulate to toxic levels.

Water-Soluble Vitamin

B-complex or vitamin C; excess excreted in urine.

Monosaccharide

Single sugar molecule; carbohydrate monomer (e.g., glucose).

Disaccharide

Two monosaccharides linked by a glycosidic bond (e.g., sucrose).

Polysaccharide

Long chain of monosaccharides connected by glycosidic bonds.

Glycosidic Bond

Covalent linkage between carbohydrate monomers; can be α or β.

Starch

α-glucose polymer that stores energy in plants.

Glycogen

Highly branched α-glucose polymer storing energy in animals.

Cellulose

Linear β-glucose polymer providing structural support in plant cell walls.

Chitin

β-glucose polymer with nitrogen; structural component of fungi cell walls and arthropod exoskeletons.

Lipid

Non-polar, hydrophobic biomolecule used for energy storage, insulation, and membrane structure.

Triglyceride

Three fatty acids esterified to a glycerol backbone; major fat storage molecule.

Saturated Fatty Acid

Fatty acid with no double bonds; straight chain that packs tightly.

Unsaturated Fatty Acid

Fatty acid with one or more double bonds; kinked chain that packs loosely.

Phospholipid

Glycerol, two fatty acids, and a phosphate group forming amphipathic membrane bilayers.

Steroid

Lipid composed of four fused hydrocarbon rings; includes cholesterol and steroid hormones.

Porphyrin

Molecule of four joined pyrrole rings with a central metal (e.g., heme, chlorophyll).

Cholesterol

Steroid that modulates membrane fluidity and serves as precursor for steroid hormones.

Protein

Polymer of amino acids linked by peptide bonds; performs diverse cellular functions.

Peptide Bond

Covalent bond between amino acid carboxyl and amino groups formed via dehydration.

Primary Protein Structure

Linear sequence of amino acids in a polypeptide chain.

Secondary Protein Structure

α-helix or β-sheet formed by hydrogen bonding between backbone atoms.

Tertiary Protein Structure

Three-dimensional folding due to R-group interactions (H-bonds, ionic, hydrophobic, disulfide).

Quaternary Protein Structure

Association of multiple polypeptide subunits into a functional protein.

Denaturation

Loss of protein’s 3-D structure (except primary), leading to loss of function.

Nucleotide

Nitrogenous base + five-carbon sugar + phosphate group; monomer of nucleic acids.

Phosphodiester Bond

Covalent linkage between nucleotides’ phosphate and sugar groups in nucleic acids.

Purine

Double-ring nitrogen base; adenine or guanine.

Pyrimidine

Single-ring nitrogen base; cytosine, uracil, or thymine.

Chargaff’s Rule

In DNA, A = T and C = G; total purines equal total pyrimidines.

Antiparallel

Orientation of DNA strands running in opposite 5’→3’ directions.

Ribose

Five-carbon sugar in RNA with an extra 2’-OH compared to deoxyribose.

Cell Theory

Concept that all living things are composed of cells, which arise from pre-existing cells.

Plasma Membrane

Selective phospholipid bilayer enclosing cell contents.

Fluid Mosaic Model

Description of membrane as dynamic lipid bilayer with embedded proteins.

Selective Permeability

Property allowing some substances to cross membrane more easily than others.

Organelle

Membrane-bound structure within eukaryotic cells performing specialized functions.

Nucleus

Organelle housing DNA and site of transcription.

Nucleolus

Region of nucleus where rRNA synthesis and ribosome assembly occur.

Ribosome

Non-membranous complex of rRNA and protein that synthesizes polypeptides.

Rough Endoplasmic Reticulum

ER studded with ribosomes; synthesizes and modifies secretory proteins.

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids, detoxifies drugs, stores Ca2+ in muscle.

Golgi Apparatus

Series of flattened sacs that modify, sort, and package proteins and lipids.

Lysosome

Vesicle containing hydrolytic enzymes for intracellular digestion and apoptosis.

Peroxisome

Organelle that breaks down fatty acids and detoxifies by producing and degrading H2O2.

Vacuole

Large vesicle for storage and transport; includes central, food, contractile types.

Microfilament

Actin filament involved in cell movement and cytokinesis.

Intermediate Filament

Fibrous protein filament (e.g., keratin) providing mechanical strength.

Microtubule

Tubulin polymer forming spindle apparatus, cilia, and flagella.

Centrosome

Microtubule-organizing center containing two perpendicular centrioles in animal cells.

Mitochondrion

Double-membrane organelle where aerobic respiration and ATP synthesis occur.

Cristae

Infoldings of inner mitochondrial membrane increasing surface area for ETC.

Chloroplast

Plant organelle containing chlorophyll; site of photosynthesis.

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated from engulfed prokaryotes.

Peripheral Membrane Protein

Protein loosely attached to membrane surface; removable by salt or pH.

Integral Membrane Protein

Protein embedded in lipid bilayer; removable by detergent.

Transmembrane Protein

Integral protein spanning entire membrane, connecting inside and outside.

Channel Protein

Membrane protein forming hydrophilic pore for passive transport of specific molecules.

Carrier Protein

Membrane protein that undergoes conformational change to transport substances.

Aquaporin

Channel protein that accelerates water transport across membranes.

Tight Junction

Cell junction forming seal to prevent paracellular transport between cells.

Desmosome

Strong junction anchoring cells via intermediate filaments; resists mechanical stress.

Gap Junction

Intercellular channel allowing direct ion and small molecule passage between cells.

Basement Membrane

Extracellular matrix layer anchoring epithelial cells to underlying tissue.

Simple Diffusion

Passive movement of small non-polar molecules across membrane without proteins.

Facilitated Diffusion

Passive transport of molecules across membrane via channels or carriers.

Primary Active Transport

Movement against gradient using ATP hydrolysis (e.g., Na⁺/K⁺ pump).

Secondary Active Transport

Coupled transport using energy of another molecule’s gradient (symport/antiport).

Endocytosis

Process of membrane engulfing material to form internal vesicle.

Phagocytosis

Cellular “eating” of large particles via pseudopod engulfment.

Pinocytosis

Non-selective uptake of extracellular fluid (“cell drinking”).

Receptor-Mediated Endocytosis

Specific uptake triggered by ligand binding, often involving clathrin.

Exocytosis

Vesicular fusion with plasma membrane releasing contents outside cell.

Hypotonic Solution

External solution with lower solute concentration causing water influx into cell.

Hypertonic Solution

External solution with higher solute concentration causing water efflux from cell.

Gram-Positive Bacteria

Bacteria with thick peptidoglycan wall staining purple; no outer membrane.

Gram-Negative Bacteria

Bacteria with thin peptidoglycan between membranes; outer LPS; stains pink.

Glycocalyx

Carbohydrate coat on cell surface providing protection and cell recognition.

Extracellular Matrix (ECM)

Network of collagen, proteoglycans, and glycoproteins providing structural support.

Collagen

Most abundant ECM protein; triple-helix fiber conferring tensile strength.

Kinesin

Motor protein moving cargo along microtubules toward cell periphery (+ end).

Dynein

Motor protein moving cargo toward microtubule minus end; drives cilia motion.

Kinetic Energy

Energy of motion possessed by moving objects.