The document discusses the structure and function of prokaryotic cells. Prokaryotic cells are much smaller and simpler than eukaryotic cells, lacking organelles like the nucleus and mitochondria. The basic structure of a prokaryotic cell includes an outer cell wall and cytoplasmic membrane, cytoplasm containing ribosomes and other inclusions, and sometimes additional structures like flagella, pili, or plasmids. The cell wall provides shape and rigidity while the membrane is semipermeable and controls movement of molecules in and out. Ribosomes perform protein synthesis and mesosomes are involved in respiration.

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