Cellular Basis of Life and Membrane Transport Vocabulary

Vocabulary flashcards covering basic cell anatomy, organelles, cell diversity, and passive/active membrane transport processes based on the lecture notes.

Cell

The basic structural and functional unit of living organisms, with the human body containing $50\text{--}100\text{ trillion}$ cells.

Principle of Complementarity

The principle stating that the biochemical activities of cells are dictated by their structure, which determines their function.

Prokaryotic Cell

A cell with a simple structure that contains DNA, lacks a nucleus and membrane-bounded organelles, has a cell wall containing peptidoglycan, and contains small ribosomes.

Eukaryotic Cell

A cell with a complex structure that contains a nucleus, membrane-bounded organelles, large ribosomes, and may have a cell wall containing chitin.

Plasma Membrane

A barrier for cell contents that separates cell contents from the surrounding environment.

Fluid Mosaic Model

The structural model of the plasma membrane constructed of two layers of phospholipids arranged tail to tail, cholesterol, proteins, and glycolipids.

Glycoproteins

Branched sugars attached to proteins that act as a cellular glue.

Glycocalyx

A sugar-rich area on the surface of a cell.

Hydrophilic

Water-loving; refers to the polar heads of phospholipids oriented on the inner and outer surfaces of the plasma membrane.

Hydrophobic

Water-fearing; refers to the nonpolar tails of phospholipids forming the center of the plasma membrane, making it impermeable to most water-soluble molecules.

Tight Junctions

Impermeable cell junctions that bind cells together into leakproof sheets.

Desmosomes

Anchoring cell junctions created by buttonlike thickenings of adjacent plasma membranes that prevent cells from pulling apart under mechanical stress.

Gap Junctions

Communicating cell junctions that allow communication between cells, enabling molecules to travel directly through channels.

Nucleus

The control center of the cell containing DNA, consisting of the nuclear envelope, nucleolus, and chromatin.

Nuclear Envelope

A double membrane bounding the nucleus that contains nuclear pores for material exchange and encloses nucleoplasm.

Nucleolus

A dark-staining region inside the nucleus that serves as the site of ribosome assembly.

Chromatin

Structures composed of DNA wound around histones present when the cell is not dividing, which condense into chromosomes during cell division.

Cytoplasm

The site of most cellular activities, composed of cytosol, inclusions, and organelles.

Cytosol

Fluid in the cytoplasm that suspends other elements and contains nutrients and electrolytes.

Inclusions

Stored materials and substances in the cytoplasm that the cell may use later.

Organelles

The metabolic machinery of the cell that perform specialized functions.

Mitochondria

The powerhouse of the cell that produces ATP, enclosed by a double membrane with an inner membrane folded into cristae.

Ribosome

Organelle made of protein and ribosomal RNA that serves as the site of protein synthesis.

Endoplasmic Reticulum

Fluid-filled tunnels that carry substances within the cell, classified as rough or smooth.

Rough ER

Endoplasmic reticulum that synthesizes proteins and utilizes transport vesicles to move proteins within the cell.

Smooth ER

Endoplasmic reticulum that lacks ribosomes, functions in lipid metabolism, and detoxifies drugs and harmful substances.

Golgi Apparatus

Organelle that modifies and packages proteins arriving from the rough ER via transport vesicles.

Secretory Vesicles

Vesicles produced by the Golgi apparatus that carry lipids and proteins to the cell membrane to release contents outside by exocytosis.

Lysosomes

Organelles containing Golgi-derived enzymes that break down waste, damaged cell components, bacteria, cell debris, and nonusable cell structures.

Peroxisomes

Organelles that detoxify harmful substances such as alcohol.

Cytoskeleton

A network of protein structures extending throughout the cytoplasm that provides internal framework, supports organelles, and assists in internal movement.

Microfilaments

The smallest elements of the cytoskeleton, made of actin, which help with cell movement and shape.

Intermediate Filaments

Cytoskeletal elements that give the cell strength and stability.

Microtubules

The largest elements of the cytoskeleton, made of tubulin, which assist with intracellular transport and cell division.

Centrioles

Organelles that generate microtubules and direct the formation of the mitotic spindle during cell division.

Cilia

Cell extensions that move materials across the cell surface, such as in the respiratory system.

Flagella

Cell extensions that propel the cell, such as in sperm cells.

Microvilli

Tiny fingerlike extensions of the plasma membrane that increase surface area for absorption.

Fibroblast

A cell that connects body parts and secretes fibers.

Erythrocyte

Red blood cell that carries oxygen in the bloodstream.

Epithelial Cell

Cell covering and lining body organs, containing intermediate fibers that resist tearing during rubbing or pulling.

Oocyte

The female reproductive cell and largest cell in the body, which divides to become an embryo upon fertilization.

Sperm

The male reproductive cell built for swimming to the egg for fertilization.

Solution

A homogeneous mixture composed of two or more components.

Solvent

The dissolving medium in a solution, present in the larger quantity.

Solute

Components present in smaller quantities within a solution.

Intracellular Fluid

Solution inside the cell containing gases, nutrients, and salts dissolved in water, composed of nucleoplasm and cytosol.

Extracellular Fluid

Interstitial fluid located on the exterior of the cell containing ingredients such as nutrients, hormones, and salts.

Passive Process

Transport method where substances cross the membrane down concentration gradients without cell ATP input.

Diffusion

Movement of particles down a concentration gradient from high to low concentration until reaching equilibrium.

Simple Diffusion

Unassisted movement of solutes directly through the plasma membrane from high to low concentration without ATP.

Osmosis

Simple diffusion of water across a selectively permeable membrane, occurring mainly through aquaporins.

Isotonic Solution

A solution with the same solute and water concentration as the cell, resulting in water moving in and out at equal rates.

Hypertonic Solution

A solution containing more solutes than the cell, causing water to move out of the cell.

Hypotonic Solution

A solution containing fewer solutes (more water) than the cell, causing water to move into the cell.

Facilitated Diffusion

Passive movement of substances from high to low concentration requiring protein channels or carrier proteins.

Filtration

Process where water and solutes are pushed through a membrane from high to low pressure by hydrostatic pressure.

Active Process

Transport method requiring cellular ATP to move substances across a membrane, often against concentration gradients.

Active Transport

Process using ATP and solute pump protein carriers to move amino acids, sugars, and ions across the membrane.

Vesicular Transport

Transport of substances across the membrane in bulk without directly crossing the membrane structure.

Exocytosis

Vesicular transport mechanism that moves substances out of the cell through vesicle fusion with the plasma membrane.

Endocytosis

Vesicular transport mechanism that moves substances into the cell by engulfing them in a vesicle.

Phagocytosis

A form of endocytosis known as cell eating, where pseudopods engulf large particles like bacteria or dead cells.

Pseudopods

Cytoplasmic extensions that surround and separate substances from the external environment during phagocytosis.

Pinocytosis

A form of endocytosis known as cell drinking, where the cell takes in extracellular fluid containing dissolved substances.

Receptor-Mediated Endocytosis

A highly selective form of endocytosis where target molecules bind to specific receptor proteins on the cell membrane before vesicle formation.

Docking Process

Mechanism in exocytosis where docking proteins on a vesicle bind to proteins on the plasma membrane to fuse and release contents.