This document provides an overview comparison of prokaryotic and eukaryotic cells. It describes several key structures and organelles found in eukaryotic cells that are not present in prokaryotes, including the nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, peroxisomes, and cytoskeleton components like microtubules, microfilaments, and intermediate filaments. The document also discusses differences in cell membranes, ribosomes, and processes like endocytosis, exocytosis, phagocytosis, and the use of flagella and cilia for motility. Overall, the document outlines some of the major distinguishing cellular features of eukaryotes versus prokaryotes.

1. Prokaryotes versus
Eukaryotes
Cell morphology, structure,
and function

2. Chicken
egg
Human red
blood cell
Large
protozoan
(Euglena)Chloroplasts
Flea
Typical bacteria
and archaea
Diameter
of DNA
VirusesProteins
Ribosomes
Amino
acids
Atoms
Scanning tunneling microscope
(STM) 0.01 nm–10 nm
Scanning electron microscope (SEM)
0.4 nm–1 mm
Transmission electron microscope (TEM)
0.078 nm–100 µm
Atomic force
microscope (AFM)
1 nm–10 nm
Compound light microscope (LM)
200 nm–10 mm
Unaided human eye
200 µm–
Mitochondrion

3. Coccus
Coccobacillus
Bacillus
Vibrio
Spirillum
Spirochete
Pleomorphic
Morphology of bacterial cells

4. Multicellular
Arrangements

5. Multicellular
Arrangements

6. Staining bacterial cells

7. Staining bacterial cells: simple stain
One dye is used: crystal violet

8. The Gram stain
 The Gram stain is based on structural differences in the cell
walls of bacteria
 One of the first steps a medical laboratory technologist
performs to identify bacterial pathogens
 Gram positive (purple/blue)
 Gram negative bacteria (pink)

9. The Ziehl-Neelsen acid-fast stain
 Mycobacterium (rod shaped cells – pink/red)
 Staphylococcus (cluster of cocci - blue)
 Used to detect
Mycobacterium
 M. tuberculosis
(tuberculosis)
 M. leprae (leprosy)

10. Schaeffer-Fulton endospore stain of Bacillus
anthracis
Resting structures, resistant to
desiccation, heat, chemicals
 Survival during adverse
environmental conditions
 Sporulation: endospore
formation
 Germination: return to
vegetative state
 Bacillus
 Clostridium  Green-dyed endospores inside red-dyed
rod shaped bacteria
 Endospores and medical significance

11. Negative stain of Klebsiella pneumoniae to detect
the capsule
Background
stain
Bacterium
Capsule
 Eosin, nigrosin or india ink can be used to stain the background
 Crystal violet to stain bacterial cells

12. Flagellar stain of Proteus vulgaris
Flagella Presence
 Number
 Arrangement
on the cell
 Help identify
pathogens
 Dyes are used to build up layers on flagella to make them visible
when using an optical microscope

13. Streptococcus
pneumoniae causes
pneumonia and
meningitis
S. pneumoniae grown from
a blood culture
Apply your knowledge to understand ….
 This arrangement is also seen in Neisseria gonorrhoeae, which causes
the sexually transmitted disease called gonorrhea

14. Streptococcus
pyogenes and strep
throat
A sputum smear showing
the typical arrangement
in chains of cocci
Apply your knowledge to understand …..

15. Sputum sample from a
patient with staphylococcal
pneumonia
Methicillin resistant Staphylococcus
aureus (MRSA)
Apply your knowledge to understand …..

16. Bacterial cells
 Within a bacterial cell there is the cytoplasm: a fluid
component surrounded by an envelope called the plasma
membrane
 Nucleoid
 Bacterial chromosome
 Ribosomes
 Synthesis of proteins
 Inclusions
 Reserve of polysaccharides, lipids, nitrogen, phosphate
 Plasmids (Not always present)
 Extrachromosomal genetic elements
Inclusions
Nucleoid
Ribosomes
Plasmid

17. Figure 4.14b
The Plasma Membrane
 Phospholipid bilayer
 Integral proteins
 Peripheral proteins
 Proteins carry out several functions including transport across the
plasma membrane

18. Thick peptidoglycan found
on the outer side of the
plasma membrane
 Gram-positive
bacteria
Thin peptidoglycan found in
the periplasmic space
 Gram-negative
bacteria
The cell wall provides structure, shape, and
protects the cell from osmotic lysis

19. Cell wall of Gram positive bacteria
 Peptidoglycan (also called murein): NAG, NAM
 Teichoic acids

20. Cell wall of Gram negative bacteria
LPS (lipopolysaccharide)
 Lipid A is an endotoxin
 O polysaccharide functions as an antigen (E. coli O157:H7)

21. Atypical Cell Walls
 Acid-fast cell walls
 Waxy lipid (mycolic acid) bound to the peptidoglycan
 Mycobacterium

22. Glycocalyx: Capsule or Slime layer
• Capsule: Organized and firmly attached to the cell wall
• Slime layer: Unorganized and loosely attached to the cell wall
 Protects from desiccation
 Confers adherence
capability
 Allows pathogens to
escape or survive
phagocytosis
 Sticky substance surrounding the outside of the bacterial cell
 Made of polysaccharides, polypeptides, or both
 Streptococcus pneumoniae, Klebsiella pneumoniae, Bacillus
anthracis

23. Fimbriae and Pili
Escherichia coli
 Fimbriae allow
attachment
 Fimbriae of E.
coli O157 enable
the bacterium to
adhere to the
lining of the small
intestine
 Causing
a severe watery
diarrhea

24.  Proteus species
are involved in
nosocomial
urinary tract
infections
Proteus vulgaris
 Fimbriae
 Flagella
 Neisseria gonorrhoeae, the pathogen colonizes the mucous
membrane of the reproductive tract by attaching with fimbriae

25. Fimbriae and Pili
 Pili are involved in motility
and genetic exchange in the
process of conjugation
 Through conjugation bacteria
acquire new capabilities
 Toxin production
 Resistance to antibiotics

26. Flagella (locomotion)
 Composed of filament, hook, and basal body, which anchors
the flagellum to the cell wall/membrane(s)
 Motile cells move toward or away from stimuli (taxis)
 Flagellar proteins are H antigens (E. coli O157:H7)

27. Arrangements of bacterial flagella
 Flagella allow movement, which in turn can allow escape from
host defense

28.  Axial filaments are
flagellum-like structures
found in spirochetes
 Causes the bacterial cell
to rotate like a corkscrew
(corkscrew motion)
Treponema pallidum (syphilis)
Axial filaments

30. Comparative analysis between prokaryotic
and eukaryotic cells

31. Eukaryotic cells
We are eukaryotes!!

32. The Nucleus
 The nucleus contains almost all of the cell’s hereditary
information (DNA)
 The nucleus of human cells can be the site of viral replication
 Certain viruses such as HIV integrate their genome into our
DNA, becoming proviruses

33. The Endoplasmic reticulum (ER)
 Systems of flattened
membranous sacs or tubules
(cisternae)
 The rough ER (with ribosomes)
 Synthesis of secretory
proteins and components of
cell membranes
 The smooth ER carries out
various functions
 Synthesis of lipids (steroids)
 Detoxification - drugs or
alcohols

34. Ribosomes
 Ribosomes are the intracellular site of protein synthesis
 Eukaryotic ribosomes (80S) differ from those of bacteria
(70S) - though both types are made of proteins and
ribosomal RNA
 Bacterial ribosomes
are the target of
antibiotics

35. The Golgi apparatus
 Modifies, sorts, and ships proteins from the ER, including
those secreted by the cells
 Produces lysosomes
The Golgi Apparatus

36.  Lysosomes are filled
with digestive
enzymes that break
down various
molecules
 Intracellular digestion
of macromolecules in
animal cells
 Lysosomes are
involved in
phagocytosis
Lysosomes
Details of the figure will not be
part of the exam!

37. Peroxisomes
 Oxidize organic substances (amino acids, fatty acids, toxic
substances such as alcohol)
 Contain catalase, an enzyme that converts H2O2 (by-
product of the oxidation reactions) into H2O and O2

38. Mitochondria
 Sites of cellular
respiration, a metabolic
process by which cells
form ATP
 Mitochondria contain
DNA and ribosomes
(similar to those of
bacteria)
 Mitochondria evolved
from bacteria

39. Plasma Membrane
“Fluid mosaic model” of the membrane

40.  Three types of cytoskeleton
components
 Microtubules
 Microfilaments
 Intermediate filaments
Cytoskeleton, Cilia, and Flagella
i.e., Keratin

41. Shigella and
actin filaments
Bordetella pertussis
and the ciliary escalator
of the respiratory tract
 Cilia and flagella are
made up of microtubules
projected outward from
the cell surface
 Cilia are not found in
prokaryotes
Cytoskeleton, Cilia, and Flagella

42. Endocytosis and Exocytosis
 Endocytosis, a process by which eukaryotic cells take in the
“material” through formation of vesicles
 Endocytosis includes
 Phagocytosis
 Pinocytosis
 Exocytosis involves moving “material” out of the cell which
is also done through the formation of vesicles

43. Phagocytosis is a defense mechanism of our
body
 Phagocytosis is a
process our body
uses against
pathogens
 Many pathogens
have found ways to
escape or survive
phagocytosis
Bacteria

44. A human cell (blue)
engulfing a yeast cell
(green)

45. Keep in mind that eukaryotic organisms you will study
include
Filamentous fungi
Yeasts
Protozoa
Helminths