Chapter 6: A Tour of the Cell

Vocabulary flashcards covering key terms and definitions from Chapter 6—A Tour of the Cell, including microscopy, cell structure, organelles, and cytoskeleton concepts.

Light Microscope

Optical instrument that uses visible light and lenses to magnify specimens for direct viewing.

Magnification

Ratio of an image’s size to the specimen’s actual size.

Resolution

Measure of image clarity; the minimum distance at which two points can be distinguished.

Organelles

Membrane-bounded structures in eukaryotic cells that perform specialized functions.

Electron Microscope

Instrument that focuses a beam of electrons to achieve higher resolution than light microscopy.

Scanning Electron Microscope (SEM)

Electron microscope that scans a gold-coated specimen’s surface to produce a 3-D image of topography.

Transmission Electron Microscope (TEM)

Electron microscope that passes electrons through a thin specimen to study internal structure.

Plasma Membrane

Selective phospholipid bilayer forming the cell boundary and regulating material passage.

Cytosol

Semifluid, jelly-like portion of cytoplasm in which organelles are suspended.

Chromosomes

DNA-containing structures that carry hereditary information.

Ribosomes

Complexes of rRNA and proteins that build polypeptides according to genetic instructions.

Prokaryotic Cell

Cell lacking a nucleus; DNA resides in an unenclosed nucleoid region.

Eukaryotic Cell

Cell whose DNA is enclosed in a nucleus and that possesses membrane-bound organelles.

Nucleoid

Non-membranous region in prokaryotes where DNA is concentrated.

Cell Wall

Rigid extracellular layer (in plants, fungi, some bacteria) that protects, supports, and prevents excess water uptake.

Cytoplasm

Entire contents of a cell bounded by the plasma membrane; excludes nucleus in eukaryotes.

Nucleus

Prominent eukaryotic organelle that houses chromosomes.

Nuclear Envelope

Double membrane enclosing the nucleus; perforated by pores.

Pore Complex

Protein structure in nuclear envelope regulating entry and exit of macromolecules.

Chromatin

DNA-protein complex constituting eukaryotic chromosomes.

Nucleolus

Nuclear region where rRNA is synthesized and ribosomal subunits assemble.

Free Ribosomes

Ribosomes suspended in cytosol that make proteins functioning within the cytosol.

Bound Ribosomes

Ribosomes attached to rough ER or nuclear envelope that make proteins for membranes, organelles, or export.

Endomembrane System

Interconnected membranes including nuclear envelope, ER, Golgi, lysosomes, vesicles, vacuoles, and plasma membrane.

Endoplasmic Reticulum (ER)

Extensive membranous network continuous with nuclear envelope; rough and smooth regions.

Smooth ER

ER region lacking ribosomes; synthesizes lipids, metabolizes carbohydrates, detoxifies drugs, stores Ca²⁺.

Rough ER

ER studded with ribosomes; produces secretory and membrane proteins.

Golgi Apparatus

Stack of flattened cisternae that modifies, sorts, and ships ER products and manufactures some macromolecules.

Cis Face (Golgi)

Receiving side of Golgi apparatus facing the ER.

Trans Face (Golgi)

Shipping side of Golgi that forms transport vesicles.

Lysosome

Membranous sac of hydrolytic enzymes that digests macromolecules and damaged organelles.

Phagocytosis

Process by which a cell engulfs particles, forming a food vacuole.

Autophagy

Lysosomal recycling of the cell’s own organelles and macromolecules.

Vacuole

Large membrane-bound vesicle with diverse storage and regulatory functions.

Food Vacuole

Vacuole formed by phagocytosis containing ingested material.

Contractile Vacuole

Vacuole in freshwater protists that pumps excess water out of the cell.

Central Vacuole

Large plant vacuole storing ions, metabolites, pigments, or toxins and absorbing water for growth.

Mitochondrion

Organelle where cellular respiration produces ATP; contains its own DNA and ribosomes.

Cristae

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

Chloroplast

Photosynthetic organelle converting solar energy to chemical energy; contains chlorophyll, DNA, ribosomes.

Thylakoid

Flattened membranous sac inside chloroplast where light reactions occur.

Granum

Stack of thylakoids inside a chloroplast.

Stroma

Fluid outside thylakoids containing chloroplast DNA, ribosomes, and enzymes.

Cytoskeleton

Network of protein fibers that supports cell shape, organizes structures, and aids movement.

Microtubules

Thickest cytoskeletal fibers of tubulin; shape cell, guide organelles, form cilia/flagella.

Microfilaments (Actin Filaments)

Thin cytoskeletal rods of actin that bear tension and aid in muscle contraction and cell motility.

Intermediate Filaments

Fibers intermediate in size that reinforce cell shape and anchor organelles.

Cilia

Short, numerous microtubule-containing projections that move fluid over cell surfaces or act as sensory antennae.

Flagella

Long, usually few, microtubule-containing appendages that propel cells with an undulating motion.

Pseudopodia

Cellular extensions of actin cytoskeleton used by amoebas and some white blood cells for crawling movement.

Cell Cortex

Actin-rich layer beneath the plasma membrane that supports cell shape and gives a gel-like consistency.

Motor Proteins

Proteins that interact with cytoskeletal filaments to move vesicles, organelles, or the whole cell.