Section 4

Vocabulary practice flashcards covering cell structure, organelles, microscopy methods, cell fractionation, and endomembrane systems based on Chapter 6 lecture notes.

Cytology

The scientific study of cell structure.

Light Microscopy (LM)

An optical technique in which visible light passes through a specimen and glass lenses, which refract the light to magnify images up to approximately $1000\times$.

Magnification

The ratio of an object's image size to its real size.

Resolution

The minimum distance two points can be separated and still be distinguished as separate points, which is about $200\,nm$ in standard light microscopy.

Contrast

The difference in brightness between dark and light areas of an image, often enhanced through staining or labelling.

Brightfield Microscopy

A light microscopy method where light passes directly through the specimen, producing little contrast in unstained cells unless stains or dyes are applied.

Phase-Contrast Microscopy

A light microscopy technique that amplifies variations in density within a specimen to enhance contrast in unstained, living cells.

Differential Interference Contrast (Nomarski) Microscopy

A light microscopy technique using optical modifications to exaggerate density differences, producing an almost 3-D image of unstained cells.

Fluorescence Microscopy

A technique that uses fluorescent dyes or antibodies to label specific molecules within a cell, which absorb ultraviolet radiation and emit visible light.

Confocal Microscopy

A technique using a laser to capture a single plane of fluorescence while excluding out-of-focus light, producing sharp 3-D reconstructions.

Deconvolution Microscopy

A computational process that takes blurry fluorescence images from multiple focal planes, digitally removing out-of-focus light and reassigning it to its source.

Super-Resolution Microscopy

An advanced optical technique that excites individual fluorescent molecules to pinpoint their position, breaking the standard $200\,nm$ resolution limit.

Electron Microscopy (EM)

A microscopy technique that uses magnets to focus a beam of electrons on or through a specimen, providing up to $100\times$ greater resolution than standard light microscopy.

Transmission Electron Microscopy (TEM)

A type of electron microscopy used to examine the internal ultrastructure of thin sections of cells.

Scanning Electron Microscopy (SEM)

A type of electron microscopy that scans the surface of a specimen to generate a 3-D image of its topography.

Cell fractionation

A laboratory technique that breaks open cells and uses centrifugation to separate organelles and other subcellular structures based on size and density.

Centrifugation

A technique that uses high-speed spinning to separate cell components based on size and density.

Cytosol

The semifluid, jellylike substance enclosed within the plasma membrane in which subcellular components are suspended.

Cytoplasm

The interior region of a cell bounded by the plasma membrane, excluding the nucleus in eukaryotic cells.

Prokaryotic Cell

A organismal cell structure lacking a membrane-enclosed nucleus and membrane-enclosed organelles, typical of Domains Bacteria and Archaea.

Eukaryotic Cell

A cell containing a membrane-bound nucleus and membrane-enclosed organelles, characteristic of Domain Eukarya.

Nucleoid

The non-membrane-enclosed region of a prokaryotic cell where its genetic material (DNA) is located.

Plasma Membrane

The selective membrane barrier enclosing the cytoplasm that regulates the entry and exit of substances.

Surface-to-Volume Ratio

The ratio of a cell's plasma membrane surface area relative to its volume; a high ratio facilitates efficient material exchange with the environment.

Nucleus

The eukaryotic organelle that houses most of the cellular DNA and contains instructions for protein synthesis.

Nuclear Envelope

A double membrane perforated by pore complexes that encloses the nucleus, separating it from the cytoplasm.

Nuclear Pore

A protein-lined channel in the nuclear envelope that regulates the transport of mRNA, proteins, and macromolecular complexes.

Nuclear Lamina

A netlike array of protein filaments lining the inner surface of the nuclear envelope that mechanically maintains nuclear shape.

Chromatin

The complex of DNA and associated proteins that forms eukaryotic chromosomes; visible as a diffuse mass in non-dividing cells.

Chromosomes

Structures consisting of a single long DNA molecule organized with proteins, carrying genetic information inside the nucleus.

Nucleolus

A dense non-membranous structure inside the non-dividing nucleus where ribosomal RNA (rRNA) is synthesized and assembled into ribosome subunits.

Ribosomes

Cellular complexes composed of rRNA and protein that serve as the sites of protein synthesis.

Free Ribosomes

Ribosomes suspended in the cytosol that primarily synthesize proteins that function within the cytosol.

Bound Ribosomes

Ribosomes attached to the outer surface of the endoplasmic reticulum or nuclear envelope that synthesize membrane-bound, organelle-targeted, or secreted proteins.

Endomembrane System

The interconnected collection of internal membranes in a eukaryotic cell that includes the nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane.

Endoplasmic Reticulum (ER)

An extensive network of membranous tubules and flattened sacs (cisternae) continuous with the outer membrane of the nuclear envelope.

ER Lumen

The internal fluid-filled compartment enclosed by the endoplasmic reticulum membrane.

Smooth ER

The portion of the endoplasmic reticulum lacking surface ribosomes, specialized for lipid synthesis, carbohydrate metabolism, drug detoxification, and calcium ion storage.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes, involved in synthesizing secretory proteins, glycoproteins, and membrane phospholipids.

Glycoproteins

Proteins that have carbohydrate molecules covalently attached to them within the endoplasmic reticulum lumen.

Transport Vesicles

Membrane-bound sacs in transit from one location in the cell to another, such as carrying products from the transitional ER to the Golgi.

Golgi apparatus

An organelle consisting of stacked, flattened membranous sacs (cisternae) that modifies, stores, sorts, and packages cellular products coming from the endoplasmic reticulum.

Cis face of Golgi apparatus

The receiving region located near the endoplasmic reticulum where transport vesicles arrive.

Trans face of the Golgi apparatus

The shipping side of the organelle, located away from the ER, that gives rise to vesicles that pinch off and travel to other cellular destinations.

Hydrolytic enzymes

Proteins that catalyze the cleavage of chemical bonds by adding water, functioning optimally within acidic cellular compartments.

Phagocytosis

A cellular process in which a cell engulfs a particle or microorganism to form a food vacuole, which then merges with a digestive organelle for hydrolysis.

Lysosome

A membranous sac of hydrolytic enzymes used by eukaryotic cells to digest macromolecules.

Vacuole

A large membrane-bound vesicle derived from the endoplasmic reticulum and Golgi apparatus that performs diverse maintenance functions in the cell.

Autophagy

The cellular process in which lysosomes degrade and recycle the cell's own organic material, such as damaged organelles.

Central vacuole

A prominent organelle in mature plant cells that functions in storage, waste breakdown, macromolecule hydrolysis, and driving cell growth through water absorption.