Tour of the Eukaryotic Cell – Vocabulary Flashcards

A set of vocabulary flashcards covering major structures, processes, and theories discussed in the lecture on eukaryotic cells.

Cell Membrane (Plasma Membrane)

Semi-permeable phospholipid bilayer with embedded proteins that regulates material entering and leaving the cell.

Cell Wall

Rigid outer layer found in plants, fungi, and some protists that provides strength, rigidity, and protection from osmotic pressure.

Cellulose

Structural polysaccharide that composes plant cell walls.

Chitin

Nitrogen-containing polysaccharide that forms fungal cell walls.

Flagella

Long, whip-like appendages that propel eukaryotic cells by waving motions.

Cilia

Short, hair-like projections that move fluid across the cell surface or propel single-celled eukaryotes.

Nucleus

Membrane-bound organelle that houses linear chromosomes and directs cellular activities.

Cytoskeleton

Network of protein filaments (microtubules, actin, intermediate filaments) that provides structural support and motility.

Microfilaments (Actin Filaments)

Thin protein filaments that maintain cell shape and drive cell movement and muscle contraction.

Microtubules

Hollow tubulin rods that form the mitotic spindle, tracks for organelle movement, and the core of cilia/flagella.

Intermediate Filaments

Ropelike fibers that provide mechanical strength and resist cell stretching.

Centrioles

Microtubule structures in animal cells that organize spindle fibers during cell division.

Lysosome

Membranous sac containing acidic hydrolase enzymes that digest and recycle macromolecules.

Peroxisome

Microbody with oxidative enzymes that break down fatty acids and toxins, producing and degrading H₂O₂ via catalase.

Vacuole

Membranous compartment for storage and transport; large central version in plant cells controls turgor pressure.

Tonoplast

Selective membrane surrounding the large central vacuole of plant cells.

Endocytosis

Active uptake of extracellular materials by plasma-membrane invagination forming vesicles.

Phagocytosis

Endocytic process in which the cell engulfs large particles or other cells (“cell eating”).

Pinocytosis

Endocytic uptake of extracellular fluid and dissolved solutes (“cell drinking”).

Exocytosis

Fusion of intracellular vesicles with the plasma membrane to release contents outside the cell.

Endomembrane System

Interconnected membranes (ER, Golgi, lysosomes, vesicles, plasma membrane) that synthesize, modify, and traffic molecules.

Endoplasmic Reticulum (ER)

Extensive membrane network continuous with the nuclear envelope that synthesizes and transports molecules.

Rough Endoplasmic Reticulum

ER studded with ribosomes; site of synthesis and initial transport of secreted and membrane proteins.

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids/steroids, stores Ca²⁺, detoxifies, and forms transport vesicles.

Golgi Apparatus

Stack of flattened sacs that modify, sort, and package proteins and lipids for transport or secretion.

Ribosome

Ribonucleoprotein particle (rRNA + proteins) that translates mRNA into polypeptides; 80S in eukaryotic cytoplasm.

Cytosol

Aqueous fluid of the cell that surrounds organelles and contains dissolved ions and nutrients.

Cytoplasm

Entire contents between the plasma membrane and nuclear envelope; cytosol plus organelles.

Mitochondrion

Double-membraned organelle that performs aerobic respiration and generates ATP (“powerhouse of the cell”).

Chloroplast

Plant plastid where photosynthesis converts light energy into glucose; contains its own DNA and ribosomes.

Thylakoid

Flattened membrane sac inside chloroplasts that houses photosynthetic pigments such as chlorophyll.

Leucoplast

Colorless plant plastid specialized for starch storage.

Selective Permeability

Property of cellular membranes that allows some substances to cross more easily than others.

Phospholipid Bilayer

Two-layered sheet of phospholipids that forms the basic structure of all cell membranes.

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated as free-living bacteria engulfed by ancestral eukaryotic cells.

Catalase

Peroxisomal enzyme that converts toxic hydrogen peroxide into water and oxygen.

Plasmodesmata

Cytoplasmic channels through plant cell walls that connect adjacent cells and allow transport of substances.

70S Ribosome

Smaller prokaryotic-type ribosome found in bacteria and inside mitochondria and chloroplasts.

80S Ribosome

Larger cytoplasmic ribosome characteristic of eukaryotic cells (60S + 40S subunits).

Nuclear Envelope

Double membrane surrounding the nucleus; continuous with the ER.

Nuclear Pores

Protein complexes in the nuclear envelope that regulate transport of RNA and proteins between nucleus and cytoplasm.

Chromatin

DNA-protein complex that packages genetic material within the nucleus; condenses into chromosomes during division.

Nucleolus

Dense region inside the nucleus where rRNA is transcribed and ribosomal subunits assemble.