Cell Structure, Function, and Membrane Transport

Vocabulary flashcards covering cell structure, organelles, membrane transport mechanisms, cell differentiation, and tonicity.

Cellular Structure

All components and organelles contained within a cell that fulfill specific functions related to the characteristics of life.

Cytoplasm

All the material contained between the plasma membrane and the nucleus of a cell.

Cytosol

The viscous fluid in the cell in which organelles and other materials are suspended.

Inclusions

Chemical substances stored within the cytosol, such as stored nutrients.

Organelles

Specialized cellular structures that perform specific functional tasks inside the cell.

Plasma Membrane

A selectively permeable phospholipid bilayer containing proteins, cholesterol, and carbohydrates that surrounds the cell and regulates transport in and out.

Nucleus

Organelle surrounded by a double membrane that contains genetic material in the form of DNA.

Chromatin

The uncoiled genetic material present in a non-dividing cell.

Nucleolus

Dense region within the nucleus responsible for manufacturing ribosomes.

Nuclear Envelope

Double-membrane structure surrounding the nucleus.

Ribosomes

Cellular structures responsible for protein synthesis, occurring either as free floating in cytosol or bound to the rough endoplasmic reticulum.

Bound Ribosomes

Ribosomes attached to the rough ER that synthesize proteins destined for export, membrane insertion, or organelle placement.

Free Ribosomes

Ribosomes floating freely in the cytosol that synthesize proteins used within the cytosol.

Endoplasmic Reticulum

Interconnected network of tubes and membranes continuous with the outer nuclear membrane, divided into Rough ER and Smooth ER.

Rough Endoplasmic Reticulum

Ribosome-studded portion of the endoplasmic reticulum involved in protein synthesis and transport to the Golgi apparatus.

Smooth Endoplasmic Reticulum

Portion of the endoplasmic reticulum lacking ribosomes that synthesizes and transports lipids, detoxifies drugs, and stores $\text{Ca}^{2+}$.

Golgi Apparatus

Stack of flattened membranous sacs (cisternae) with cis and trans faces that accepts, processes, packages, and ships cellular products from the rough ER.

Vacuole

Membrane-bound storage organelle containing water and nutrients, found primarily in plants and bacteria.

Peroxisome

Membrane-bound vesicle containing enzymes responsible for cellular detoxification.

Lysosome

Membrane-bound vesicle containing digestive enzymes for intracellular digestion.

Mitochondria

Double-membrane organelle featuring folded inner membranes (cristae) that converts organic molecules into ATP through cellular respiration.

Metabolism

The sum of all chemical processes involved in building up or breaking down complex molecules within an organism.

Catabolic Reactions

Metabolic reactions that break down complex molecules into simpler ones, releasing energy.

Anabolic Reactions

Metabolic reactions that build complex molecules from simpler precursors, requiring energy input.

Cell Differentiation

The process by which unspecialized cells acquire specific structures and functions.

Stem Cell Hierarchy

Developmental progression of stem cells from totipotent cells (zygote) to pluripotent embryonic cells and multipotent adult stem cells.

Phospholipid

Amphipathic lipid component of cell membranes composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails.

Fluid Mosaic Model

Structural concept describing the plasma membrane as a fluid phospholipid bilayer embedded with a mosaic of proteins, cholesterol, and carbohydrates.

Integral Membrane Protein

Protein that spans the entire lipid bilayer and primarily functions to transport specific molecules across the plasma membrane.

Peripheral Membrane Protein

Protein attached superficially to the plasma membrane surface or to integral proteins, supporting membrane architecture and participating in metabolic functions.

Cholesterol

Lipid molecule embedded within the phospholipid bilayer that modulates membrane fluidity.

Glycocalyx

Carbohydrate coating formed by glycoproteins and glycolipids on the cell surface, involved in cell binding, signaling, and identification.

Selectively Permeable

Property of the plasma membrane that allows certain molecules to pass while restricting others based on size and chemical properties.

Simple Diffusion

Passive movement of small nonpolar or uncharged molecules directly across the lipid bilayer down their concentration gradient.

Facilitated Diffusion

Passive transport of polar or charged substances down their concentration gradient through channel or carrier membrane proteins.

Sodium-Potassium Pump

Primary active transport membrane protein that utilizes ATP to pump $\text{Na}^+$ out of the cell and $\text{K}^+$ into the cell against their concentration gradients.

Endocytosis

Active transport mechanism in which the plasma membrane invaginates to engulf extracellular substances into vesicles or vacuoles.

Phagocytosis

Form of endocytosis in which a cell engulfs large particles or debris to form a vacuole.

Pinocytosis

Form of endocytosis in which a cell internalizes fluid and dissolved solutes into small vesicles.

Receptor-Mediated Endocytosis

Targeted endocytosis process triggered when specific extracellular ligands bind to membrane receptors.

Exocytosis

Active process by which materials packaged in secretory vesicles are exported out of the cell by fusing with the plasma membrane.

Solvent

The dissolving medium in a solution, which in biological systems is water.

Solute

Substance that is dissolved in a solvent to form a solution.

Tonicity

The relative solute concentration of an extracellular solution compared to the intracellular fluid of a cell.

Hypertonic Solution

A solution with a higher concentration of solute relative to another solution or cell cytoplasm.

Hypotonic Solution

A solution with a lower concentration of solute relative to another solution or cell cytoplasm.

Isotonic Solution

A solution with an equal solute concentration compared to another solution or cell cytoplasm.

Osmosis

Passive diffusion of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.