1. Functional Anatomy of Prokaryotic and Eukaryotic Cells
Chapter 4
Functional Anatomy of Prokaryotic and Eukaryotic Cells

2. Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells
Learning objective: compare and contrast overall cell structure of prokaryotes and eukaryotes.
Comparing Prokaryotic and Eukaryotic Cells
Prokaryote comes from the Greek words for prenucleus.
Eukaryote comes from the Greek words for true nucleus.

3. Prokaryote Eukaryote Cell membrane Cytoplasm
One circular chromosome, not in a membrane
No histones
No organelles
Peptidoglycan cell walls
Binary fission
Cell membrane
Cytoplasm
Paired chromosomes, in nuclear membrane
Histones
Organelles
Polysaccharide cell walls
Mitotic spindle

4. Average size: 0.2 -1.0 µm  2 - 8 µm (1 x 10-6 m)
Learning objective: Identify the three basic shapes of bacteria.
Average size: µm  µm (1 x 10-6 m)
Are unicellular and most multiply by binary fission
Basic shapes:
COCCUS BACILLUS SPIRAL

5. Arrangements Pairs: diplococci, diplobacilli Clusters: staphylococci
Chains: streptococci, streptobacilli

6. Arrangements of cocci:
Can be determined by division of planes.

7. Arrangements of bacilli:

8. Arrangements of spiral bacteria:

9. Double-stranded helix formed by Bacillus subtilis.
Bacillus cells often remain attached to each other, forming extended chains.

10. Unusual shapes (Prokaryotes) Star-shaped Stella
Square Haloarcula (halophilic archaea – salt-loving)
Most bacteria are monomorphic (single shape)
A few are pleomorphic (many shapes)
Figure 4.5

11. Learning objective: Describe the structure and function of the glycocalyx, flagella, axial filaments, fimbriae, and pili.
Prokaryote cell

12. Glycocalyx Outside cell wall Usually sticky
A capsule is neatly organized
A slime layer is unorganized & loose glycocalyx
Extracellular polysaccharide (EPS) allows cell to attach
Capsules prevent phagocytosis
Protects against dehydration or loss of nutrients.
Figure 4.6a, b

13. Flagella
Long filamentous appendages of a filament, hook, and basal body
Outside cell wall
Made of chains of flagellin
Attached to a protein hook
Anchored to the wall and membrane by the basal body
Figure 4.8

14. Flagella Arrangement
Four arrangements of flagella:
Figure 4.7

15. Motile Cells Rotate flagella to run or tumble
Move toward or away from stimuli (positive and negative taxis)
Flagella H proteins are antigens (e.g., E. coli O157:H7)

16. Motile Cells
A Proteus cell swarming may have peritrichous flagella. (from all sides)
Figure 4.9

17. Axial Filaments (endoflagellum)
Endoflagella
In spirochetes
Anchored at one end of a cell
Rotation causes cell to move
Figure 4.10a

18. Fimbriae and Pili Are short, thin appendages
Fimbriae of this E. Coli cell allow attachment (velcro). Cell is beginning to divide.
Pili are used to transfer DNA from one cell to another
Figure 4.11

19. Learning objectives: Compare/contrast cell walls of gram-positive bacteria, gram-negative bacteria, archaea, and mycoplasmas.
Differentiate between protoplast, spheroplast, and L form.
Cell Wall
Prevents osmotic lysis (protects against changes in water pressure)
Made of peptidoglycan (in bacteria = NAG+NAM+amino acids) – penicillin interferes with production of peptidoglycan
Contributes to disease capability and site of action of some antibiotics.
Figure 4.6a, b

20. Peptidoglycan (murein)
Polymer of disaccharide N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM)
Linked by polypeptides
The small arrows denote where penicillin interferes with linkage of peptidoglycan rows.
Figure 4.13a

21. Gram positive vs. gram negative cell walls
Figure 4.13b, c

22. Gram-positive cell walls Gram-negative cell walls
Thick peptidoglycan
Teichoic acids (alcohol+phosphate)
In acid-fast cells, contains mycolic acid (waxy lipid) – allows them to be grouped into medically significant types.
Thin peptidoglycan (subject to mechanical breakage)
No teichoic acids
Outer membrane:
Evades phagocytosis
Barrier to certain anti-biotics

23. Gram-Positive cell walls
Teichoic acids:
Lipoteichoic acid links to plasma membrane
Wall teichoic acid links to peptidoglycan
May regulate movement of cations (+ charge)
Polysaccharides provide antigenic variation (identification)
Figure 4.13b

24. Gram-Negative Outer Membrane
Lipopolysaccharides, lipoproteins, phospholipids.
Forms the periplasm between the outer membrane and the plasma membrane.
Protection from phagocytes, complement (30+ liver proteins that protect host), antibiotics.
O polysaccharide antigen, e.g., E. coli O157:H7.
Lipid A is an endotoxin.
Porins (proteins) form channels through membrane to pass other molecules

25. Gram-Negative Outer Membrane
Figure 4.13c

26. Gram Stain Mechanism
Crystal violet-iodine (CV-I) crystals form in cell combining with peptidoglycan
Gram-positive
Alcohol dehydrates peptidoglycan
CV-I crystals do not leave
Gram-negative
Alcohol dissolves outer membrane and leaves holes in peptidoglycan
CV-I washes out

29. Atypical Cell Walls Mycoplasmas (Genus) Lack cell walls
Sterols in plasma membrane
Archaea
Wall-less, or
Walls of pseudomurein (lack NAM and D amino acids, peptidoglycan)

30. Damage to Cell Walls
Lysozyme digests disaccharide in peptidoglycan (gram+ cell walls destroyed, gram- damaged, resulting in spheroplast).
Spheroplast is a wall-less Gram-positive cell.
Penicillin inhibits peptide bridges in peptidoglycan.
Protoplast is a wall-less cell.
L forms are wall-less cells that swell into irregular shapes (gram+ and -).
Protoplasts and spheroplasts are susceptible to osmotic lysis.

31. Plasma (cytoplasmic) Membrane
Learning objectives: Describe the structure, chemistry, and functions of prokaryotic plasma membrane.
Define simple diffusion, facilitated diffusion, osmosis, active transport, and group translocation.
Figure 4.14a

33. Plasma Membrane – Fluid Mosaic Model
Selectively permeable
Phospholipid bilayer
Peripheral proteins
Integral proteins
Transmembrane proteins
Figure 4.14b

34. Fluid Mosaic Model Membrane is as viscous as olive oil.
Proteins move to function
Phospholipids rotate and move laterally
Figure 4.14b

35. Plasma Membrane
Carry enzymes for metabolic reactions: nutrient breakdown, energy production, photosynthesis
Selective permeability allows passage of some molecules
Enzymes for ATP production
Photosynthetic pigments on foldings called chromatophores or thylakoids
Damage to the membrane by alcohols, quaternary ammonium (detergents) and polymyxin antibiotics causes leakage of cell contents.

37. Movement Across Membranes
High to low concentration:
Movement may be passive (no energy expenditure – diffusion or facilitated diffusion):
Simple diffusion: Movement of a solute from an area of high concentration to an area of low concentration. (ions move until equilibrium reached)
Facilitative diffusion: Solute combines with a transporter protein in the membrane.

38. Movement Across Membranes
Figure 4.17

39. Movement Across Membranes
Osmosis (always involves water):
Movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water.
Osmotic pressure
The pressure needed to stop the movement of water across the membrane.
Figure 4.18a

40. Osmosis
Figure 4.18c-e

41. Movement Across Membranes
Low to high concentration (against gradient) – cell must expend energy:
Active transport of substances requires a transporter protein and ATP.
Group translocation of substances requires a transporter protein and PEP. (phospheonolpyruvic acid)

42. Cytoplasm
Cytoplasm is the fluid substance inside the plasma membrane (water, inorganic and organic molecules, DNA, ribosomes, and inclusions)
Figure 4.6a, b

44. Nuclear Area
Learning objectives: Identify functions of the nuclear area, ribosomes, and inclusions.
Nuclear area (nucleoid) – contains single long, continuous, double-stranded DNA called bacterial chromosome.
Bacteria can contain plasmids – circular DNA
Figure 4.6a, b

45. Ribosomes = rRNA + proteins
Sites of protein synthesis (rRNA) – free floating, not tied to endoplasmic reticulum as in eukaryotes.
Figure 4.6a

46. Ribosomes
The letter S refers to Svedberg units = relative rate of sedimentation.
Because of differences in prokaryotic and eukaryotic ribosomes, the microbe can be killed by antibiotics while eukaryotic host cell is unaffected.
Figure 4.19

47. Inclusions Metachromatic granules (volutin) Phosphate reserves
FUNCTION
Metachromatic granules (volutin)
Polysaccharide granules
Lipid inclusions
Sulfur granules
Carboxysomes
Gas vacuoles
Magnetosomes
Phosphate reserves
Energy reserves
Ribulose 1,5-diphosphate carboxylase for CO2 fixation
Protein covered cylinders
Iron oxide (destroys H2O2)

48. Iron-oxide inclusions in some gram-negative bacteria that act like magnets.

49. Endospores Resting cells formed for survival
Learning objective: Describe the functions of endospores, sporulation, and endospore germination.
Resting cells formed for survival
Sporulation: Endospore formation
Resistant to desiccation, heat, chemicals
Bacillus, Clostridium
Germination: Return to vegetative state

50. Endospores tend to form under conditions of stress.

51. Eukaryotic Cells Comparing Prokaryotic and Eukaryotic Cells
Prokaryote comes from the Greek words for prenucleus.
Eukaryote comes from the Greek words for true nucleus.

55. Eukaryotic Flagella and Cilia
Prokaryotic flagella rotate, eukaryotic flagella wave
Euglena (evolutionary
building block)

56. Flagella and Cilia
Flagella are few and long (motility), cilia are numerous and short (motility and move substances along cell surface)
Microtubules
Tubulin
9 pairs + 2 arrangements
Figure 4.23c

57. Cell Wall and Glycocalyx
Learning objective: Compare and contrast prokaryotic and eukaryotic cell walls and glycocalyxes.
Cell wall
Plants, algae, some fungi contain cellulose
Carbohydrates
Cellulose, chitin (fungal), glucan & mannan (yeast)
Glycocalyx surround animal cells (strength, attachment to other cells)
Carbohydrates extending from animal plasma membrane
Bonded to proteins and lipids in membrane

58. Plasma Membrane Phospholipid bilayer in both p. and e. cells
Learning objective: Compare and contrast prokaryotic and eukaryotic plasma membranes.
Phospholipid bilayer in both p. and e. cells
Peripheral proteins
Integral proteins
Transmembrane proteins
Sterols
Glycocalyx carbohydrates not found in p. cells except Mycoplasma bacteria

59. Plasma Membrane
Selective permeability allows passage of some molecules
Simple diffusion
Facilitative diffusion
Osmosis
Active transport
Endocytosis
Phagocytosis: Pseudopods extend and engulf particles (solids)
Pinocytosis: Membrane folds inward bringing in fluid and dissolved substances (liquids)

60. Eukaryotic Cell
Cytoplasm Substance inside plasma membrane and outside nucleus
Cytosol Fluid portion of cytoplasm
Cytoskeleton Microfilaments, intermediate filaments, microtubules
Cytoplasmic streaming Movement of cytoplasm throughout cells
Learning objectives:
Define organelle.
Describe the functions of the nucleus, endoplasmic reticulum, ribosomes, Golgi complex, lysosomes, vacuoles, mitochondria, chloroplasts, peroxisomes, and centrosomes.

61. Organelles Specialized membrane-bound structure in cytoplasm:
Nucleus Contains chromosomes (DNA)
ER Transport network, ribosomes
Golgi complex Membrane formation and protein secretion
Lysosome Digestive enzymes
Vacuole Brings food into cells and provides support
Mitochondrion Cellular respiration (ATP)
Chloroplast Photosynthesis (70S ribosomes)
Peroxisome Oxidation of fatty acids; destroys H2O2

62. Eukaryotic Cell Not membrane-bound:
Ribosome Protein synthesis (translation)
Centrosome Consists of protein fibers and centrioles
Centriole Mitotic spindle formation

63. Eukaryotic Nucleus
Figure 4.24

64. Endoplasmic Reticulum
Rough ER contains ribosomes – site of protein translation
Smooth ER performs various functions:
Synthesizes phospholipids, fats, steroids
In liver: glucose release and detoxify toxins
Creates vesicles
Figure 4.25

65. Ribosomes 80S Membrane-bound Attached to ER Free In cytoplasm 70S
In chloroplasts and mitochondria

66. Golgi Complex
Golgi complex modifies, sorts, and packages proteins received from the ER; discharges proteins via exocytosis; replaces portions of the plasma membrane; and forms lysosomes (digestive enzymes).
Figure 4.26

67. Lysosomes (digestive enzymes)
Figure 4.22b

68. Vacuoles (storage of toxins, food, water)
Figure 4.22b

69. Mitochondrion (furnace of the cell)
Site of the Krebs Cycle, which produces the energy currency of the cell - ATP
Figure 4.27

70. Chloroplast
Structure similar to mitochondria – the reverse side of respiration:
C6H12O6 + O2 = H2O + CO2 + ATP
Photosynthesis:
H2O + CO2 + sun = C6H12O6 + O2
Figure 4.28

71. Endosymbiotic Theory Learning objective:
Discuss evidence that supports the endosymbiotic theory of eukaryotic evolution.
Mitochondria and chloroplasts resemble bacteria in size and shape as do their ribosomes
These organelles contain circular DNA like prokaryotes and can reproduce apart from their host cell
Figure 10.2