1. Bacteria are unicellular, prokaryotic microorganisms that have a cell wall made of murein. They can reproduce through binary fission or form endospores. 2. Bacteria are classified by their morphology and staining characteristics. Gram-positive bacteria have a thick peptidoglycan layer while gram-negative bacteria have a thinner layer and an outer membrane. 3. Bacterial cells have a cell wall, cell membrane, cytoplasm, and sometimes surface appendages like flagella, fimbriae, and pili. They can obtain energy through photosynthesis or chemosynthesis and reproduce through asexual or sexual processes like transformation, transduction, and conjugation.

1. Bacteria
Dr Renjana PK
Assistant Professor of Botany
Govt College, kodanchery

2. Unicelluar
Prokaryotic
Cell wall is made of mucopeptide
Flagella, fimbriae and pili
Single circular circular chromosome- nucleoid ,
plamids & episome
Mesosomes
Binary fission, endospore and cyst formation
Sexual reproduction- conjugation,
transformation & transduction
Simplest,
Smallest,
Most successful
Prokaryotic
Microbes
Leuwenhoek
Monera

3. Gram’s staining
Gram
positive
Gram
negative
Crystal
Violet
Gram’s
iodine
Ethyl
alcohol
Safranine

4. Morphology
Unicellular-
1. Cocci – Monococci, Diplococci, Streptococci,
Staphylococci
2. Bacilli – Monobacilli, Diplobacilli, Streptobacilli
3. Spirilla
4. Spirochaetes
5. Vibrios
6. Stalked
7. Budding
Mycelial – Branched or unbranched

6. BUDDING BACTERIA
STALKED BACTERIA

7. Structure of bacterial cell

9. Cell wall
 Multilayered
 Murein – Heteropolymer
 Mucopeptide (Peptidoglycan)
– N-Acetyl glucosamine & N-
acetyl muramic acid by β-1,4
linkages, cross-linked by short
peptide chains
 Gram positive- Thick and
simple organization,
homogenous, 80 % is
peptidoglycan, teichoic acid
 Gram negative- Thin,
complex, 10-20 %
peptidoglycan, lipoprotein
layer & lipopolysacharide layer
Rigid, protect from
osmotic lysis
Antigenic properties

14. Surface
appendages
Flagella –
Organs of locomotion
Made of flagellin
Basal body, Hook & Filament
Basal body consists of 2 pairs of rings(L. P, S & M)
 Fimbriae & Pili –
Cell to cell & cell to surface attachment - aggregation
Fimbriae are short & numerous
Pili- long & sparse, connect 2 cells during conjugation
Flagella
Pili
Fimbriae

16. 1. Atrichous
2. Monotrichous
3. Amphitrichous
4. Lophotrichous
5. Peritrichous

19. GLYCOCALYX/
CELL COAT
 Gelatinous covering
 Polysacharides & proteins
 Tough & organized-
Capsule
 Loose mass- Slime layer
 Imparts virulence,
Protection

20. Cytoplasm & cell organelles
Memnbrane bound organelles are absent
 Bacterial chromosome- Genophore in nucleoid region
 Plasmids/episomes – Extra chromosomal, circular, free or
integrated
 Lamellae & Chromatophores- Photosynthetic bacteria
 Ribosomes – 70S
 Mesosomes- Inflodings of plasma membrane
 Reserve food materials- Glycogen, lipid, polyphosphate
(volutin) granules
 Gas vesicles- Spindle shaped, planktonic species
 Carboxysomes- Proteinaceous, CO2 fixation enzymes
 Magnetosomes- help bacteria align along magnetic field,
optimum O2 concen.

22. Based on source of energy
Saprotrophy
Parasitism
Symbiosis
Phototrophy
Chemotrophy
Lithotrophy & Organotrophy based on the
source of electrons
Phototrophy
Photolithotrophy Photoorganotrophy
Chemotrophy
Chemolithotrophy Chemoorganotrophy

24. Bacterial
Photosynthesis
Bacterial
chemosynthesis
 Use light as the source of
energy
 Green sulphur bacteria,
purple sulphur bacteria &
purple non-sulphur bacteria
 Chlorobium, Chromatium,
Rhodospirillum
 Hydrogen donor is H2S,
thiosulphate, alcohol etc.
 Anoxygenic
 Bacteriochlorophyll &
bacterioviridine
 Energy of oxidation of
inorganic compounds
 Aerobic & free living soil
bacteria
 Nitrifying bacteria, sulphur
bacteria, iron bacteria
 Oxidise NH3, NO2, SO4, H2S
etc.

25. Bacterial
reproduction
Vegetative
Asexual
SexualFission
Fragmentation
Budding
Endospore Formation
Cysts
Transformation
Transduction
Conjugation

26. BINARY FISSION
DNA replication
Cytokinesis

27. Sporulation
 Protoplast is concentrated at
one end
 Multi-layered wall
 Gets cut off from the rest of
the cell
 Protoplast core- DNA, tRNA,
enzymes
 Wall- Inner membrane, cortex,
outer membrane & sporecoat
 Exosporium
 Cortex- Dipicolinic acid, Ca++
& peptidoglycan
 Non flagellated & non
motile spores –
ENDOSPORES
 Resistant, Spherical or
oval
 Gram positive bacteria-
Bacillus, Clostridium
 Low nutrient conditions,
High O2 concent.,
Certain cations
 Dormant during unfav
conditions- perennatinf
str.

29. SEXUAL
REPRODUCTION
 True sexual reproduction is
absent
 No meiosis, plasmogamy
and karyogamy
 No crossing over
 Produces only partial
diploids called mesozygotes
 Endogenote & Exogenote
combine to form
recombinant genome
 Unilateral gene transfer

30. Transformation
Transduction
Conjugation
Griffith
Zinder &
Lederberg
Lederberg &
Tatum

31. Transformation

33. Transduction

34. Transduction

39. Bacterial conjugation

40. Between F+ & F- cells

42. Between Hfr& F- cells