1) Bacteria are very small, single-celled prokaryotes that can be identified by their shape, including bacilli which are rod-shaped, spirilla which are spiral-shaped, and cocci which are sphere-shaped. 2) Bacteria have a cell wall, cell membrane, cytoplasm, and a single circular chromosome but no nucleus. They reproduce through binary fission. 3) Bacteria can be beneficial by aiding decomposition, producing antibiotics, or helping in agriculture through nitrogen fixation, but can also cause disease by secreting toxins or metabolizing their host.

1. Bacteria
Name-Sudipta Sarkar
Class- XI Sec-Sc(B)
Roll no.-27

2. Acknowledgement
 I would like to express my special thanks of gratitude to
my Biology teacher Mrs Smita as well as our principal
madam Dr. Suchitra Bhattacharya who gave me the
golden opportunity to do this wonderful project for OTBA
on the topic “Bacteria” which also helped me in doing a
lot of Research and I came to know about so many new
things I am really thankful to them.
Secondly i would also like to thank my parents and
friends who helped me a lot in finalizing this project
within the limited time frame.

3. Contents
SRL # Topic
1 Introduction (with a picture of Bacteria)
2 Comparision of the size of Bacteria with other organisms
3 Key concept of Bacteria
4 Structure of Bacteria
5 Identification of Bacteria on the basis of shape
6 Mode of reproduction of the Bacteria
7 Nutrition and growth
8 Speciality of Bacteria
9 Identification of Bacteria
10 Bacterial Cell wall
11 Hazards of Bcteria
12 Beneficts of bacteria
13 Conclusion
14 Bibliography

4. INTRODUCTION
Bacteria are VERY small!

5. Euglena 100 µm
Plant cell 35-80 µm
Animal cell 5-30 µm
Spirocheta 10 µm
Bacteria
are small
compared
to cells
with
nuclei
Virus 20-200 nm

6. Bacteria
compared to
white blood
cell that will
eat it!

7. Key Concepts about Bacteria
 Kingdom Monera
 Prokaryote=no nucleus or internal
compartments
 All are single cells
 Single circular piece of DNA

8. Structure of Bacteria
Structure Function
Cell Wall Protects and gives shape
Outer
Membrane
Protects against antibodies
Cell
Membrane
Regulates movement of
materials, contains enzymes
important to cellular
respiration
Cytoplasm Contains DNA, ribosomes,
essential compounds
Chromosome Carries genetic information.
It is circular

9. Structure of Bacteria
Plasmid Contains some genes
obtained through
recombination
Capsule
& Slime
Layer
Protects the cell and
assist in attaching cell to
other surfaces
Endospo
re
Protects cell against harsh
environments
Pilus Assists the cell in
attaching to other
surfaces
Flagellu
m
Moves the cell

10. Shapes- How bacteria are
identified!
 Bacilli- rod shaped
 Spirilla- spiral shaped
 Cocci- sphere shaped
 Staphylococci- grape-like clusters
 Streptococci- in chains

11. Bacillus bacteria are rod shaped

12. Spirillium bacteria have a
corkscrew shape

13. Coccus bacteria are sphere or
ball shaped

14. Staphylobacteria occur in clumps,
such as this staphylococcus bacteria
that cause common infections of cuts

15. Streptobacteria occur in chains,
like this streptococcus bacteria

16. Bacterial Reproduction:
Binary Fission

17. Conjugation
 Genetic information transferred on plasmids -
and sometimes antibiotic resistance

18. Nutrition and Growth
 Autotroph- producer, makes energy from
environmental sources
 Chemoautotrophs- Take Hydrogen from NH3 or
H2S and oxidize it using the energy to make amino
acids and proteins
 Photoautotrophs- photosynthetic- Uses sunlight
for energy

19. Nutrition and Growth
 Heterotroph- feed on organic material formed
by other organisms
 Decomposers
 Secrete enzymes in their organic environment
and then absorb the nutrients
 They can metabolize their host

20. Endospores
 Some bacteria can form endospores, which
are non-replicative cell forms that are highly
resistant to environmental factors.
Endospore

21. Gram Stain- Another way to
identify Bacteria
Purple= Gram Positive Pink= Gram Negative

22. Bacterial Cell Walls
•Peptidoglycan is the material that makes up bacterial cell walls
Thicker peptidoglycan
layer but not outer
membrane means gram +
Thinner peptidoglycan layer
with an outer membrane
means gram -

23. How do Bacteria cause
disease?
 Metabolize their host for food (Heterotrophic
bacteria)
 Secrete a toxin which can attack other body
parts (Botulism is an example)
 Contain an endotoxin in their cell wall which
is released when the bacterium dies. An
example of this is salmonella.

24. How can Bacteria work to our
benefit?
 Digest waste at sewage plants
 Chemical industry- make acetone and
butanol
 Pharmaceutical- vitamins, antibiotics, insulin
 Food- yogurt, cheese, alcoholic beverages
 Decomposer
 Nitrogen fixers
 Symbiosis

25. Conclusion
 Through this project I came to know a lot
about Bacteria its characteristic features and
also how to identify it. This project was a
great help to me as this information might
help me in my future.

26. Bibliography
 https//:www.ncertbooks.co.in
 https//:www.bacteriapics.com

27. THANK YOU