Structure of the Cell: Microscopic Structure of Cellular Compartments

Vocabulary-style practice flashcards focusing on cell structure, organelles, microscopy, and histology based on the lecture notes.

Histology

The study that helps students understand the structure of cells, tissues, and organs and correlates structure with physiology.

Virtual microscopy

A method of viewing a digitalized microscopic specimen on a computer screen.

Hematoxylin

A blue cationic stain that binds to anionic (negatively charged) basophilic sites in tissue sections.

Eosin

A pink anionic stain that binds to acidophilic (positively charged) tissue components.

Basophilic structures

Regions such as the nucleus, nucleolus, and ergastoplasm that stain blue to purple because of phosphate groups of nucleic acids or ionized sulphate groups.

Acidophilic structures

Regions such as cytoplasmic filaments and extracellular fibers that stain pink to red because of cationic groups or ionized amino groups.

Cytoplasm

The part of the cell located outside the nucleus, consisting of organelles, cytoskeleton, and inclusions suspended in an aqueous gel called the cytoplasmic matrix.

Nucleus

The largest organelle within the cell containing the genome and enzymes necessary for $DNA$ replication and $RNA$ transcription.

Rough-surfaced endoplasmic reticulum (rER)

A region of endoplasmic reticulum associated with ribosomes and serving as the site of protein synthesis and modification.

Smooth-surfaced endoplasmic reticulum (sER)

A region of endoplasmic reticulum involved in lipid and steroid synthesis, detoxification in the liver, and $Ca$ ion uptake in muscle cells.

Golgi apparatus

A membranous organelle composed of flattened cisternae responsible for modifying, sorting, and packaging proteins and lipids.

Mitochondria

Double-membraned organelles that provide energy to the cell by producing $ATP$ in the process of oxidative phosphorylation.

Lysosomes

Small organelles containing digestive enzymes for the digestion of macromolecules, formed from endosomes.

Peroxisomes

Small organelles involved in the production and degradation of $H_2O_2$ and the degradation of fatty acids.

Endosomes

Membrane-bounded compartments that sort proteins delivered via endocytotic vesicles and redirect them to their final destination.

Ribosomes

Structures composed of $rRNA$ and proteins that are essential for protein synthesis.

Proteasomes

Protein complexes that enzymatically degrade damaged and unnecessary proteins into small polypeptides and amino acids.

Nissl bodies

Basophilic parts of the cytoplasm in neurons composed of granular endoplasmic reticulum stacks and free ribosomes.

Euchromatin

Transcriptionally active, pale or lightly stained areas of nuclear chromatin representing dispersed uncoiled chromosome regions.

Heterochromatin

Transcriptionally inactive, condensed coiled $DNA$ that appears as basophilic clumps under a light microscope.

Nucleolus

A spherical non-membranous structure within the nucleus, rich in $rRNA$ and proteins, serving as the site of $rRNA$ synthesis.

Nuclear lamina

A meshwork of intermediate filaments (lamins $A$, $B$, and $C$) that stabilizes the nuclear envelope and maintains nuclear shape.

Nuclear pore complex

A cylinder-like structure formed by $8$ multidomain protein subunits arranged in an octagonal framework at the periphery of each nuclear pore.

Lipofuscin

A brownish-gold "wear and tear" pigment that accumulates in long-living, non-dividing cells like neurons and muscle cells.

Hemosiderin

A deep brown, iron-containing pigment formed by the indigestible residues of hemoglobin after phagocytosis of erythrocytes.

Melanin

A brownish-black pigment found in melanocytes that gives color to skin, hair, and eyes.

Simple squamous epithelium

A single layer of flat cells, such as the endothelium lining blood vessels or mesothelium covering the peritoneum.

Pseudostratified epithelium

A type of epithelium where all cells contact the basal lamina but not all reach the lumen, such as in the trachea or epididymis.

Transitional epithelium (urothelium)

A specialized stratified epithelium lining the urinary bladder that can stretch and change shape.

Microtubules

Long, rigid cylindrical tubules ($25\,nm$ in diameter) composed of $13$ parallel protofilaments made of $\alpha$ and $\beta$ tubulin dimers.

Actin filaments (Thin filaments)

Polarized structures ($6-8\,nm$ in diameter) formed by the polymerization of $G-actin$ into $F-actin$, requiring $K^+$, $Mg^{++}$, and $ATP$.

Intermediate filaments

Rope-like fibers ($8-10\,nm$ in diameter) that show tissue specificity and provide mechanical strength and resistance to extracellular forces.