Editors: Steven R. Goodman, C.L. Lundell (The University of Texas at Dallas)
Professor of Life Sciences and Cell Biology
Duration: 45 Minutes
Subject: Cell Biology (Prokaryotic Cell)
Instructor: Dr. Nompumelelo Mkhwanazi, PhD (Virology)
Differences:
Prokaryotic vs. Eukaryotic Cells
Archaebacteria vs. Eubacteria
Gram-positive vs. Gram-negative Bacteria
Prokaryotic Cell Structure:
Organelles
Respiration
Genetic Material
Mesosomes
Review Questions:
Bacterial cell wall structure
Components of prokaryotic cell wall
Types of archaebacteria
Differences between Gram-positive and Gram-negative bacteria
Prokaryotic genetic material
First observed by Robert Hooke (1665)
Cells are the fundamental units of life
New cells arise from division of existing cells
Prokaryotes: Unicellular organisms lacking membrane-bound nuclei and organelles.
Ranges from 0.05 µm to 600 x 80 µm.
Smaller cells have an increased surface area relative to volume, enhancing transport rates and growth.
Cocci: Spherical
Bacilli: Rod-shaped
Filamentous: Multinucleate filaments
Spirilla: Rigid spirals
Spirochetes: Flexible spirals
Pleomorphic: Variable shapes
Components:
Cytoplasm
Plasma Membrane
Periplasmic Space
Cell Wall
Slime Layer/Capsule
Flagella/Pili
Contains:
Water and various components
Ribosomes (protein synthesis)
Inclusion bodies (organic/inorganic granules)
Phospholipid bilayer with proteins.
Retains cytoplasm, selective permeability, nutrient and waste transport, energy generation, and receptor proteins for signaling.
Archaebacteria:
Ancient, thrive in extreme environments (acidic, high heat).
Different cellular components compared to Eubacteria.
Major groups: Methanogens, Halophiles, Thermophiles.
Eubacteria: Common bacteria in neutral conditions.
Archaeal membranes use isoprenoids, ether linkages, and sometimes monolayers.
No complex internal membranes; presence of mesosomes (membrane invaginations).
Provides shape and protection from osmotic lysis.
Virulence factors may include LPS in Gram-negative bacteria.
Gram-positive: Thick peptidoglycan, teichoic acids.
Gram-negative: Thin peptidoglycan, outer membrane, periplasmic space, LPS.
Contains a circular double-stranded DNA, without a nuclear membrane.
Circular, double-stranded DNA, often used in genetic manipulation.
Present in all cells, serve as protein synthesis sites.
Prokaryotic ribosomes (70S) differ from eukaryotic ribosomes (80S).
Projections aiding in surface attachment.
Types: Ordinary pili (host adherence) and sex pili (bacterial conjugation).
Enables bacterial motility.
Composed of flagellin protein subunits.
Invitation for questions and further discussion.