Molecular Biology: Overview of Cells, Research Models, Biomolecules, and Membranes

Vocabulary flashcards generated from lecture material covering cell structure, origin and evolution, research model organisms, light/electron microscopy, cell culture, biomolecules, enzyme kinetics, and membrane dynamics.

Prokaryotic Cells

Cells that lack a nuclear envelope and membrane-bound cytoplasmic organelles, typically measuring $\text{1}\text{--}\text{10 bring}\text{ }\nu\text{m}$ (or $\text{1}\text{ }\nu\text{m}$) in diameter with a single circular DNA molecule.

Eukaryotic Cells

Cells containing a distinct nucleus that separates genetic material from the cytoplasm, as well as membrane-bound cytoplasmic organelles and multiple linear DNA molecules.

RNA World

A hypothesized early evolutionary period in which RNA served as the initial genetic system due to its ability to serve as a template for its own replication and catalyze chemical reactions.

Phospholipids

Amphipathic lipid molecules consisting of water-insoluble hydrophobic hydrocarbon chains joined to water-soluble hydrophilic head groups, which spontaneously aggregate into a bilayer in water.

Glycolysis

The anaerobic breakdown of glucose to lactic acid that yields a net gain of $2\text{ ATP}$ molecules per glucose molecule.

Oxidative Metabolism

An efficient aerobic metabolic pathway in which glucose is completely broken down to $\text{CO}_2$ and $\text{H}_2\text{O}$, yielding $36\text{ to }38\text{ ATP}$ molecules.

Cyanobacteria

The largest and most complex group of prokaryotes in which oxygenic photosynthesis evolved.

Endosymbiosis

The evolutionary process by which eukaryotic organelles, such as mitochondria and chloroplasts, arose from prokaryotic cells living inside the ancestors of eukaryotes.

Resolution

The ability of a microscope to distinguish two objects separated by small distances, which limits detailed observation more critically than magnification.

Fluorescence Recovery After Photobleaching (FRAP)

A technique in which a region of a cell expressing a GFP-labeled protein is bleached with a laser to measure the rate of protein movement by tracking fluorescence recovery over time.

Fluorescence Resonance Energy Transfer (FRET)

A method used to detect protein-protein interactions by fusing candidate proteins to GFP variants such that excitation energy transfers from GFP1 to GFP2 only when the two proteins interact.

Confocal Microscopy

An optical imaging technique that focuses a pinpoint of light at a specific depth in a specimen and collects emitted light through a confocal aperture, allowing only in-focus light to reach the detector.

Differential Centrifugation

A method of subcellular fractionation that separates cell components based on size and density through a series of centrifugations at increasing speeds.

Primary Culture

The initial cell culture established directly from isolated animal or plant tissue.

HeLa Cells

The first established human cancer cell line, isolated in 1951 by George Gey from a cervical carcinoma biopsy taken from Henrietta Lacks.

Glycosidic Bond

The covalent bond formed between simple sugars through a dehydration reaction that eliminates a molecule of water.

Triacylglycerols

Nonpolar fats composed of three fatty acids linked to a single glycerol molecule, which serve as the primary form of cellular energy storage.

Phosphodiester Bond

The covalent linkage joining individual nucleotides together between the $5'$ phosphate group of one nucleotide and the $3'$ hydroxyl group of another.

Peptide Bond

The covalent linkage formed between the $\text{N-terminal}$ $\text{α-amino}$ group of one amino acid and the $\text{C-terminal}$ $\text{α-carboxyl}$ group of another in a polypeptide chain.

Activation Energy

The energy barrier required for a reactant molecule to reach a high-energy transition state, which enzymes lower to accelerate reaction rates.

Induced-Fit Model

A model of enzyme catalysis where substrate binding distorts the conformations of both the enzyme and the substrate to bring them closer to the transition state.

Serine Proteases

A family of proteolytic enzymes, including chymotrypsin and trypsin, whose active sites contain a catalytic triad of serine ($\text{Ser-195}$), histidine ($\text{His-57}$), and aspartate ($\text{Asp-102}$).

Allosteric Regulation

A regulatory mechanism in which an inhibitor or activator binds to a site distinct from the active site, inducing a conformational change that modifies enzyme activity.

Fluid Mosaic Model

The model describing biological membranes as a two-dimensional fluid lipid bilayer with embedded integral membrane proteins and attached peripheral membrane proteins.

Carrier Proteins

Membrane transport proteins that selectively bind specific small molecules and undergo conformational changes to release the bound molecule on the opposite side of the membrane.