http://www.expertsmind.com/topic/biology/microbiology-92241.aspx

1. Introduction: Cells
• Cell – basic unit of life
• Based on the organization of their cellular
structures, all living cells can be divided
into two groups: eukaryotic and
prokaryotic
• eukaryotic cell types - Animals, plants,
fungi, protozoans, and algae
• prokaryotic cell types - bacteria

2. Prokaryotic Cells
• much smaller (microns) and more simple than
eukaryotes
• prokaryotes are molecules surrounded by a
membrane and cell wall.
• they lack a true nucleus and don’t have membrane
bound organelles like mitochondria, etc.
• large surface-to-volume ratio : nutrients can easily
and rapidly reach any part of the cells interior

3. Structure of A Prokaryotic Cell
Dr Ekta Chourasia

4. Structure of A Prokaryotic Cell
• Outer layer – two components:
1. Rigid cell wall
2. Cytoplasmic (Cell/ Plasma) membrane –
present beneath cell wall
• Cytoplasm – cytoplasmic inclusions, ribosomes,
mesosomes and nucleus
• Additional structures – plasmid, slime layer, capsule,
flagella, fimbriae (pili)

5. Function of Cell Components
• Cell wall
1. Shape, rigidity
2. 10-25 nm thick
3. Composed of peptidoglycan/ mucopeptide (N
acetyl glucosamine & N acetyl muramic acid)
• Cytoplasmic membrane – semipermeable
membrane: controls the inflow and outflow of
metabolites

6. Function of Cell Components
• Ribosomes – protein synthesis
• Mesosomes –
1. Multilaminated structures formed as
invaginations of plasma membrane
2. Principal sites of respiratory enzymes
3. Coordinate nuclear & cytoplasmic division
during binary fission
• Intracytoplasmic inclusions – reserve of energy &
phosphate for cell metabolism

7. Additional Organelles
1. Plasmid –
• Extranuclear genetic elements consisting of
DNA
• Transmitted to daughter cells during binary
fission
• May be transferred from one bacterium to
another
• Not essential for life of the cell
• Confer certain properties e.g. drug
resistance

8. Additional Organelles
2. Slime layer & capsule –
• Viscous layer secreted around the cell wall.
• Protects bacteria from lytic enzymes
• Inhibits phagocytosis
3. Flagella – organs of locomotion
4. Fimbriae/ Pili – 10-20µ long, organs of adhesion

9. The Cell, Structure & Function
The structure of a Prokaryotic cell ?
Protects the cell and maintains its shape
Cell Wall Thick cell wall with little lipid: Gram positive
Thin cell wall with 2 layers: Gram negative
Capsule Some bacteria have a slimy layer of Polysaccharides for protection.
70s
protein synthesis
Ribosomes
Flagellum motility
Nuclear
Genetic material : DNA
Material
Plasmid rings of genetic material for antibiotic Resistance
Mesosome For Respiration