The Cell - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to cell structure, organelles, membranes, cytoskeleton, endomembrane system, transport, and extracellular features.

Cell

The basic structural and functional unit of life; all body processes depend on cellular activity.

Organelles

Functional components within a cell that carry out specific tasks; includes membrane-bound and non-membrane-bound structures.

Membrane-bound organelles

Organelles surrounded by a phospholipid membrane (e.g., nucleus, ER, Golgi, mitochondria, lysosomes, peroxisomes).

Non-membrane-bound organelles

Organelles without a surrounding membrane (e.g., ribosomes, cytoskeleton, centrosome, proteasome).

Plasma membrane

The cell’s outer membrane; a phospholipid bilayer with proteins that controls what enters and leaves the cell.

Phospholipid bilayer

Two-layer arrangement with hydrophilic heads facing outward and hydrophobic tails inward; forms the basic framework of the plasma membrane.

Cholesterol

Sterol within the membrane that modulates fluidity and stability.

Glycoprotein

Protein with carbohydrate attached; often involved in signaling and cell recognition.

Glycolipid

Lipid with carbohydrate attached; contributes to cell recognition and membrane stability.

Integral membrane protein

Proteins embedded in the bilayer, often spanning it; hydrophobic regions interact with the interior.

Peripheral membrane protein

Proteins attached to the membrane surface; not embedded in the bilayer.

Cytoplasm

The material between the plasma membrane and nucleus, including cytosol, cytoskeleton, and organelles.

Cytosol

The gel-like intracellular fluid in which organelles reside; site of many metabolic reactions.

Nucleus

Cell's control center housing DNA and coordinating gene expression; enclosed by a double membrane with pores.

Nucleolus

Nuclear region where ribosomal RNA is synthesized and ribosomal subunits begin to form.

Nuclear envelope

Double membrane surrounding the nucleus containing nuclear pores for material exchange.

Ribosome

Ribonucleoprotein complex that synthesizes proteins; can be free in cytosol or bound to rough ER.

Rough endoplasmic reticulum

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

Smooth endoplasmic reticulum

ER lacking ribosomes; synthesizes lipids, metabolizes carbohydrates, detoxifies substances; forms transport vesicles.

Golgi apparatus

Stack of flattened membranes that modifies, sorts, and packages proteins for secretion or delivery; cis face receives vesicles, trans face ships them.

Vesicle

Small membrane-bound sac that transports substances between organelles or to/from the plasma membrane.

Lysosome

Digestive organelle containing enzymes; digests endocytosed material and damaged organelles.

Peroxisome

Organelle involved in lipid metabolism and detoxification; beta-oxidation of fatty acids.

Mitochondrion

Powerhouse of the cell; produces ATP through cellular respiration; contains its own circular DNA and cristae.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for respiration.

Proteasome

Large protein complex that degrades damaged or unnecessary proteins via ubiquitin tagging.

Endomembrane system

Network of membranes (ER, Golgi, vesicles, lysosomes, plasma membrane, nuclear envelope) that exchanges materials via vesicles and coordinates synthesis, modification, and shipping.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that provides structural support, organizes organelles, and enables movement.

Microfilaments

Actin filaments; provide cell surface support and enable movement.

Intermediate filaments

Rope-like filaments providing mechanical strength and stabilizing cell junctions (keratin is an example).

Microtubules

Hollow tubules that organize the cytoskeleton, form the mitotic spindle, and serve as tracks for vesicle transport.

Centrosome

Structure near the nucleus that organizes microtubules; contains a pair of centrioles and is important for cell division.

Centriole

Cylindrical structure within the centrosome that organizes microtubules during cell division.

Cilia

Short, hair-like projections that move substances along the cell surface or move fluid over a surface.

Flagellum

Long, whip-like projection used for cell movement (e.g., sperm).

Microvilli

Small, finger-like projections that increase surface area of the cell membrane; supported by actin filaments; common in intestinal cells.

Endocytosis

Process of taking in material by vesicle formation from the plasma membrane.

Exocytosis

Process of releasing substances from the cell via vesicle fusion with the plasma membrane.

Diffusion

Passive movement of molecules from high to low concentration; no energy required.

Osmosis

Diffusion of water across a selectively permeable membrane.

Facilitated diffusion

Passive transport using membrane proteins to move specific molecules down their concentration gradient.

Active transport

Movement of substances against their concentration gradient requiring energy (ATP) via pumps.

Na+/K+ pump

Sodium-potassium ATPase; maintains electrochemical gradients by pumping Na+ out and K+ in.

Ribosome (bound vs free)

Ribosome: protein-synthesizing complex; can be free in cytosol or bound to rough ER; bound ribosomes produce secreted/membrane/lysosomal proteins.

Ribosome synthesis location

Ribosomes function in protein synthesis; free ribosomes synthesize intracellular proteins, bound ribosomes synthesize proteins for secretion or membranes.

Nucleoplasm

Fluid inside the nucleus containing dissolved solutes and chromatin.

Nuclear pores

Channels in the nuclear envelope that regulate movement of molecules between the nucleus and cytoplasm.

Extracellular matrix

Space outside the cell composed of glycoproteins and collagen; provides structural support and interacts with cytoskeleton via integrins.

Tight junction

Zonula occludens; membrane proteins form strands sealing adjacent cells to prevent paracellular passage.

Desmosome

Anchoring junction with protein plaques and intermediate filaments providing mechanical strength.

Gap junction

Intercellular channels formed by connexons allowing direct passage of ions and small molecules between neighboring cells.

Inclusions

Non-membrane-bound stores of materials within cells (e.g., glycogen granules, lipid droplets) not considered organelles.