This document discusses the anatomy and classification of bacteria. It begins by classifying microorganisms as either prokaryotes or eukaryotes. Bacteria are prokaryotes and are smaller than eukaryotic cells, requiring microscopy to view. Bacteria morphology is described based on their shape (cocci or bacilli) and arrangement (singly, in pairs, chains, or clusters). Gram staining distinguishes between gram positive and gram negative bacteria based on cell wall structure. The bacterial cell is described as having an outer cell wall, cytoplasmic membrane, cytoplasm containing structures like ribosomes and nucleoid, and appendages like flagella or pili. Key differences in the cell walls of gram positive

1. BACTERIAL ANATOMY
Dr. Sumesh Kumar Dash
Department of Microbiology
IMS & SUM Hospital

2. CLASSIFICATION
Microorganism are grouped under 2
I. Prokaryotes (Bacteria & Blue-green algae)
II. Eukaryotes (Fungi, Parasites, other algae)
Viruses are neither prokaryotes nor
eukaryotes as they lack the characteristics of
living thinks except replication.

5. SIZE
• Bacteria size in micrometer and virus size in
nanometer
• Bacteria observed by light microscope and
Viruses observed by electron microscope
• To see microorganisms – staining is used

6. MORPHOLOGY OF BACTERIA
• Depending on their shape;
 Cocci- oval/spherical cells
 Bacilli- rod shaped
• Arrangement;
Singles Pairs
Chains clusters
• Based on gram staining property;
 Gram positive
 Gram negative

8. BACTERIAL CELL
• Outer layer/Envelope-
cellwall
cytoplasmic/plasma membrane
• Cytoplasm- mesosomes
ribosomes
vacuoles
nucleoid
• Appendages- capsule
flagella
fimbriae/pili

9. CELL WALL
• Chemically composed of peptidoglycan

10. GRAM POSITIVE CELL WALL
 Peptidoglycan layer
50-100 layers thick
16-80nm
 Teichoic acids
2 types:
Cell wall teichoic acid
Lipoteichoic acid

11. GRAM NEGATIVE CELL WALL
 Peptidoglycan layer
1-2 layer thick
2-3nm
Outer membrane
1. Porin proteins
2. Lipopolysaccharide (LPS)
• Lipid A
• Core polysaccharide
• O side chain /O antigen

12. DIFFERENCE BETWEEN GRAM POSITIVE &
GRAM NEGATIVE CELL WALL
Characters GRAM + GRAM -
peptidoglycan layer Thick Thin
Aromatic and sulphur
containing amino acids
Absent Present
Teichoic acids Present Absent
Gram stain Violet Red

13. FUNCTIONS OF CELL WALL
Maintaining the cells characteristic shape
Providing a rigid platform for surface appendages- flagella,
fimbriae/pili all emanate from the wall and extend beyond it.
Providing attachment sites for bacteriophage
Be the sites of major antigenic determinant of cell surface-
endotoxcity
Site of action of many antibiotics & resistance

14. CYTOPLASMIC/CELL MEMBRANE
5-10nm thick
Phospholipid bilayer
With integral and peripheral proteins
Selective permeability i:e -
semipermeable
Site of ATP production
Viability

15. CYTOPLASM
• Viscous watery solution containing organic & inorganic
solutes, biosynthetic components which required for the
growth & cell division, together with genetic material.
• Contains RIBOSOMES,
MESOSOMES
INTRACYTOPLASMIC INCLUSION BODIES
VACUOLES
NUCLEOUS

16. RIBOSOMES
• Sites for protein
synthesis.
• 10-20 nm in size.

17. MESOSOMES / Chondroids
• Vesicular/convoluted/multilaminated
• More prominent in G+.
• LOCATION:
Often found next to septa, in dividing
bacteria or seen attached to nuclear body.
• FUNCTION:
Site of bacterial respiration

18. INTRACYTOPLASMIC INCLUSIONS
• Storage sites for nutrients/energy.
• Formed under nutritional deficiency conditions & disappear in
the presence of excess nutrients
Staining
Toluidine blue, Neisser, Albert, Acid-fast, wet films
Electron microscopy

19. VACUOLES
• Vacuoles are fluid containing cavities
• Separated from cytoplasm by a membrane
• Function - uncertain

20. NUCLEOID
• Genetic material arranged in irregular shape
• Oval, Elongated
• Have no nuclear membrane
• Seen by Electron Microscope
Plasmid
 Extrachromosomal ds circular DNA.
 Not essential for life.
 Present singly or in multiple numbers.
 Episomes- when integrated with chromosomal DNA.
 Drug resistance and toxigenicity

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