5/28/25 Cytology

Vocabulary flashcards covering key terms and definitions from the Cytology Review lecture, including cell structure, membrane dynamics, organelles, and cellular processes.

Cytology

The study of cells, their structure, function, and chemistry.

Organelle

Highly organized, often membrane-bound cellular structure that performs a specific function inside the cell.

Cell Membrane (Plasma Membrane)

Semipermeable lipid bilayer that surrounds the cell, regulates entry/exit of substances, and houses receptors.

Phospholipid Bilayer

Double layer with hydrophilic outer heads and hydrophobic inner tails forming the main barrier of the cell membrane.

Integral (Transmembrane) Protein

Protein embedded across the membrane; forms channels, carriers, or receptors for signaling.

Peripheral Protein

Membrane-associated protein attached to integral proteins; functions in cytoskeletal anchoring or enzyme activity.

Glycocalyx

Fuzzy carbohydrate coating on external membrane surface involved in cell recognition, adhesion, and immune response.

Semipermeable

Property allowing selective passage of certain molecules while restricting others.

Diffusion (Simple)

Passive movement of lipid-soluble molecules or ions through protein channels down their concentration gradient.

Facilitated Diffusion

Carrier- or channel-mediated passive transport specific to the size, shape, or charge of the molecule.

Active Transport

Energy-requiring transport of substances against a gradient via carrier proteins (e.g., Na⁺/K⁺ pump).

Na⁺/K⁺ Pump

Primary active transport mechanism exchanging 3 Na⁺ out for 2 K⁺ into the cell, essential in muscle and nerve tissue.

Mechanically-Gated Ion Channel

Channel that opens when the membrane is deformed (stretch, pressure).

Temperature-Gated Ion Channel

Channel that opens in response to heat or cold stimuli.

Ligand-Gated Ion Channel

Channel that opens when a specific chemical messenger (ligand) binds to its receptor site.

Voltage-Gated Ion Channel

Channel that opens or closes in response to changes in membrane potential.

G-Protein–Coupled Receptor (GPCR)

Integral receptor that, upon ligand binding, activates a G-protein to modulate intracellular signaling pathways.

Cytoplasm

Cell contents outside the nucleus, including organelles, inclusions, cytoskeleton, and cytosol.

Cytosol

Jelly-like fluid portion of cytoplasm in which organelles are suspended.

Inclusion

Storage component (e.g., glycogen, lipid droplets) found in cytoplasm; may or may not be membrane-bound.

Nucleus

Cell control center containing DNA; regulates growth, maturation, replication, and apoptosis.

Nuclear Envelope

Double membrane surrounding the nucleus, perforated by large pores for molecular trafficking.

Nucleolus

Dense non-membranous region of the nucleus where rRNA and ribosomal subunits are assembled.

Ribosome

Non-membranous particle composed of rRNA and protein; site of protein synthesis (translation).

Transcription

Nuclear process of copying DNA sequence into messenger RNA (mRNA).

Translation

Cytoplasmic process where ribosomes decode mRNA to synthesize proteins.

Endoplasmic Reticulum (ER)

Membranous network involved in synthesis and transport; subdivided into rough and smooth regions.

Rough Endoplasmic Reticulum (RER)

ER studded with ribosomes; synthesizes proteins destined for membranes, lysosomes, or secretion.

Smooth Endoplasmic Reticulum (SER)

ER lacking ribosomes; synthesizes lipids, detoxifies chemicals, and participates in glycogen breakdown.

Golgi Apparatus

Stack of flattened sacs that processes, packages, and ships proteins; forms lysosomes and secretory vesicles.

Lysosome

Membrane-bound vesicle containing hydrolytic enzymes for intracellular digestion of macromolecules.

Secretory Vesicle (Granule)

Membrane pouch that stores and transports substances to be released from the cell.

Peroxisome

Small membrane-bound organelle containing oxidases; detoxifies poisons such as alcohol and peroxides.

Mitochondrion

Double-membrane “powerhouse” that generates ATP via oxidative phosphorylation.

Cristae

Infoldings of the inner mitochondrial membrane increasing surface area for ATP production.

ATP (Adenosine Triphosphate)

Primary cellular energy currency used for transport, chemical synthesis, and mechanical work.

Cytoskeleton

Non-membranous network of protein filaments and tubules providing structure and facilitating movement.

Microfilament

Thin actin filament involved in cell shape, membrane support, and muscle contraction.

Microtubule

Hollow tubular structure that supports cell shape, enables transport, and forms cilia and mitotic spindle.

Centriole

Cylindrical bundle of organized microtubules essential for spindle formation during cell division.