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Bacteria
Name-Sudipta Sarkar
Class- XI Sec-Sc(B)
Roll no.-27
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.
ContentsSRL # 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
INTRODUCTION
Bacteria are VERY small!
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
Bacteria compared to white blood cell that will eat it!
Key Concepts about Bacteria
Kingdom Monera Prokaryote=no nucleus or internal
compartments All are single cells Single circular piece of DNA
Structure of BacteriaStructure 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
Structure of BacteriaPlasmid Contains some genes
obtained through recombination
Capsule & Slime Layer
Protects the cell and assist in attaching cell to other surfaces
Endospore
Protects cell against harsh environments
Pilus Assists the cell in attaching to other surfaces
Flagellum
Moves the cell
Shapes- How bacteria are identified!
Bacilli- rod shaped Spirilla- spiral shaped Cocci- sphere shaped
Staphylococci- grape-like clusters Streptococci- in chains
Bacillus bacteria are rod shaped
Spirillium bacteria have a corkscrew shape
Coccus bacteria are sphere or ball shaped
Staphylobacteria occur in clumps, such as this staphylococcus bacteria that cause common infections of cuts
Streptobacteria occur in chains, like this streptococcus bacteria
Bacterial Reproduction:Binary Fission
Conjugation
Genetic information transferred on plasmids - and sometimes antibiotic resistance
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
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
Endospores
Some bacteria can form endospores, which are non-replicative cell forms that are highly resistant to environmental factors.
Endospore
Gram Stain- Another way to identify BacteriaPurple= Gram Positive Pink= Gram Negative
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 -
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.
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
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.
Bibliography
https//:www.ncertbooks.co.in https//:www.bacteriapics.com
THANK YOU