1. Prokaryotic and Eukaryotic Cells

2. Prokaryotic vs. Eukaryotic
No true nucleus
No organelles
Complex cell walls containing peptioglycan
Divide by binary fission
True nucleus
Organelles
Histone protein associated with DNA
Simple cell walls
Divide by mitosis

3. Bacterial Shapes Coccus – round Bacillus – rod Spiral
Vibrio – comma shaped
Spirochete - helical

4. Coccus / Arrangement

5. Bacillus / Arrangement

6. Other Shapes

7. Bacterial Shapes
Most bacteria exhibit only one shape, they are said to be MONOMORPHIC
Some bacteria can exhibit many shapes, they are said to be PLEOMORPHIC
Members of genus Corynebacterium are pleomorphic

8. Bacterial Cell

9. Structures outside the cell wall
Glycocalyx – general term for anything that surrounds the cell
Organized and firmly attached outer layer is called a CAPSULE
Capsules are often important in bacterial virulence
Loosely attached and unorganized outer layer is called a SLIME LAYER

10. Bacterial capsules

11. Flagella Some bacteria are motile by means of flagella
The arrangement of the flagella can be in several ways:
Monotrichous – single flagella at one end
Amphitrichous – flagella at each end
Lophotrichous – two or more flagella at one end
Peritrichous – flagella spread over the entire cell

12. Escherichia coli

13. Fimbriae and Pili
Short, numerous hair like appendages on the cell are called FIMBRIAE
Used for attachment to surfaces, like your teeth
PILI are longer than fimbriae, only one or two per cell and used to transfer genetic material between bacteria
Sex pili

14. E. Coli - fimbriae

15. Bacterial Cell Wall
All bacteria, except for one genus, are surrounded by a rigid cell wall
Cell wall is composed of a complex macromolecule called PEPTIDOGLYCAN
Function of the cell wall is to
Maintain the shape of the cell
Prevent the cell from rupturing in high water pressure
Anchor point for flagella

16. Cell Wall Comparison Gram + cell Many layers of peptidoglycan
Thick rigid structure
Strongly binds crystal violet in the Gram stain procedure making the cells blue
Gram – cell
One or two layers of peptidoglycan
Outer lipopolysaccharide layer (LPS) – toxin
Periplasmic space
Lightly binds crystal violet in the Gram procedure

17. Gram + Cell Wall

18. Gram – Cell Wall

19. Can a bacteria survive without a cell wall?
Yes, but only special conditions
The enzyme lysozyme can break down the protein of the cell wall
Gram + cell in an isotonic environment + lysozyme = protoplast
Gram – cell in an isotonic environment + lysozyme = spheroplast

20. Acid-fast cells Cell wall is about 60% peptidoglycan
Cell wall contains MYCOLIC ACID
Waxy lipid substance
Cells generally stain as Gram +
Strongly bind carbol fuchsin in the acid-fast staining procedure
Cells stain a bright purple red color in the acid-fast procedure

21. Plasma Membrane Phospholipid bilayer with associated proteins
Selective permeability
Nutrient breakdown
Energy production

23. Nuclear area Bacterial cells contain ONE chromosome
Circular in structure
Just DNA, no associated proteins
Some cells contain PLASMIDS
Plasmids are separate from the main chromosome
Also circular in structure, but smaller
Contain only a few genes
Often carry genes for antibiotic resistance

24. Ribosomes Protein synthesis Prokaryotic ribosomes are 70S in size
Eukaryotic ribosomes are 80S in size
Difference in size is important in antibiotic activity

25. Endospores Resting stage for certain bacteria
Spores form when nutrients become depleted
Spores are highly resistant to heat and drying
Two genera of bacteria that form spores are Bacillus and Clostridium
Spores germinate when placed in fresh media
NOT a reproductive process, it’s SURVIVAL for the cells

27. Movement Across Membranes
Simple diffusion – passive
Facilitated diffusion – passive
Osmosis – passive
Active transport – requires the cell use energy

28. Simple Diffusion

29. Facilitated Diffusion

30. Osmosis

31. Active Transport Cell uses energy in the form of ATP
Nutrients are concentrated inside the cell against the concentration gradient
Transporters in the cell membrane are responsible for this active process

32. Eukaryotic Cell