Chapter 4: Anatomy of Prokaryotes and Eukaryotes — Vocabulary

A set of vocabulary-style flashcards covering key prokaryotic and eukaryotic anatomical terms from Chapter 4.

Prokaryote

A unicellular organism that lacks a true nucleus; primitive bacteria; reproduce asexually.

Morphology

The study of the shape or form of prokaryotes.

Cocci (coccus)

Round or spherical bacteria.

Bacillus (bacilli)

Rod-shaped bacteria.

Spirochete

Spiral-shaped bacteria.

Pleomorphic

Bacteria that do not have a single, defined shape.

Eubacteria

The true, conventional bacteria with cell walls containing peptidoglycan.

Archaea

A domain of prokaryotes that often live in extreme environments; lack peptidoglycan in cell walls.

Extremophiles

Organisms (often archaea) that thrive in extreme conditions (e.g., very low pH, high temperature).

Glycocalyx

A layer of polysaccharides and/or polypeptides secreted by the cell, outside the cell wall.

Capsule

A tightly organized glycocalyx layer firmly attached to the cell wall; can increase virulence and protect from immune defenses.

Slime layer

A loosely organized glycocalyx layer; aids attachment and provides some protection and communication.

Flagellum

A structure that enables motility; can be at poles or surround the cell.

Taxis

Directed movement of a cell toward or away from a stimulus.

Positive taxis

Movement toward a stimulus.

Negative taxis

Movement away from a stimulus.

Chemotaxis

Movement toward or away from chemical stimuli.

Phototaxis

Movement toward or away from light.

Axial filaments (endoflagella)

Internal flagella used by spirochetes that rotate the cell body like a corkscrew.

Pili

Long protein tubes used mainly for attachment and gene transfer; not primarily for movement.

Fimbriae

Short, numerous pili used for attachment to surfaces.

Pili (F pilus)

The long conjugation pilus used for genetic exchange between bacteria.

Gram-positive

Bacteria with a thick peptidoglycan layer and no outer membrane; stain purple.

Gram-negative

Bacteria with a thin peptidoglycan layer and an outer membrane containing LPS; stain pink.

Peptidoglycan

A polymer of sugars and amino acids forming the bacterial cell wall; also called murein.

Murine (murein)

The peptidoglycan component of bacterial cell walls.

Porins

Protein channels in the outer membrane that allow molecule passage.

Lipopolysaccharide (LPS)

A component of the outer membrane of Gram-negative bacteria; can act as an endotoxin.

Liprotein

A lipid-protein complex associated with membranes, especially in the outer membrane.

Phospholipid

A lipid with a phosphate group forming the bilayer of cell membranes.

Cytoplasmic membrane

Phospholipid bilayer surrounding the cytoplasm; also called the plasma membrane.

Fluid mosaic model

Description of the cell membrane as a dynamic mosaic of lipids and proteins.

Diffusion

Passive movement of molecules down their concentration gradient.

Simple diffusion

Direct diffusion of small or nonpolar molecules across the membrane without transport proteins.

Facilitated diffusion

Diffusion across a membrane via integral proteins; still passive.

Osmosis

Diffusion of water across a semipermeable membrane.

Active transport

Movement of substances against their concentration gradient; requires energy.

Isotonic

Environment with equal solute concentration inside and outside the cell; balanced water movement.

Hypotonic

Environment with lower solute concentration outside; water influx can cause lysis.

Hypertonic

Environment with higher solute concentration outside; water efflux can cause dehydration.

Nucleoid

Region in prokaryotes where the main circular double-stranded DNA is located; not membrane-bound.

Plasmids

Small circular DNA molecules outside the nucleoid; carry accessory genes; transferable.

Ribosome (70S)

Prokaryotic ribosome composed of 50S and 30S subunits; site of protein synthesis.

50S subunit

Large subunit of the 70S ribosome.

30S subunit

Small subunit of the 70S ribosome.

Endospore

Dormant, highly resistant structure formed by some bacteria to survive harsh conditions.

Sporulation

Process of endospore formation.

Germination

Return of a dormant endospore to a vegetative, actively growing cell.

Vegetative state

Active, reproducing state of a bacterium after germination.

Eukaryote

Organisms with a true nucleus; can be unicellular or multicellular; larger than prokaryotes.

Flagella (eukaryotic)

Lipid-anchored, whip-like appendages that propel eukaryotic cells via undulating motion.

Cilia

Short, numerous hair-like structures that beat to move the cell or fluid around it.

Glycocalyx (eukaryotes)

Glycoproteins/glycolipids on the cell surface; insulation and protection, may aid in recognition.

Cell wall (eukaryotes, not peptidoglycan)

External layer in some eukaryotes made of materials like chitin, cellulose, or silica.

Chitin

Structural polysaccharide found in fungal cell walls and some invertebrates.

Cellulose

Polysaccharide component of plant cell walls; found in some algae and protists.

Endomembrane system

Network of membranes including the nucleus, ER, Golgi, lysosomes, and vesicles that exchange materials.

Nucleus

Membrane-bound organelle containing the cell’s DNA and nucleoplasm.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores for transport.

Nucleolus

Region within the nucleus where ribosomal RNA is synthesized.

Golgi apparatus

Modifies, sorts, and packages proteins for secretion or delivery to other organelles.

Endoplasmic reticulum (ER)

Membrane network with rough (ribosome-studded) and smooth regions; protein and lipid synthesis.

Rough ER

ER studded with ribosomes; site of protein synthesis for secretion and membranes.

Smooth ER

ER lacking ribosomes; site of lipid synthesis and detoxification processes.

Mitochondrion

Organelle producing ATP; has its own DNA and ribosomes; inner membrane folded into cristae.

Cristae

Folds of the inner mitochondrial membrane increasing surface area for energy production.

Matrix

Innermost fluid-filled region of the mitochondrion.