1. Cell biology Class-2

2. Prokaryotic cell prokaryotes include the kingdoms of simple bacteria. prokaryotes include the kingdoms of simple bacteria. Simply stated, prokaryotes are molecules surrounded by a membrane and cell wall Simply stated, prokaryotes are molecules surrounded by a membrane and cell wall

4. Prokaryotic cells lack membrane enclosed "organelles“. Prokaryotic cells lack membrane enclosed "organelles“. Prokaryotic cells may have photosynthetic pigments Prokaryotic cells may have photosynthetic pigments Example - cyanobacteria ("blue bacteria"). Example - cyanobacteria ("blue bacteria").

5. Prokaryotic cells have external Prokaryotic cells have external -Whip-like flagella for locomotion. -Hair like pili for adhesion.

7. Prokaryotic cells come in multiple shapes: Prokaryotic cells come in multiple shapes: –cocci (round), –baccilli (rods), and –spirilla or spirochetes (helical cells).

8. Internal Structure: Bacteria have a very simple internal structure, and no membrane-bound organelles. Bacteria have a very simple internal structure, and no membrane-bound organelles. Nucleoid Nucleoid Ribosome's Ribosome's Storage granules Storage granules Endospore Endospore

9. Nucleoid DNA in the bacterial cell is generally confined to this central region. DNA in the bacterial cell is generally confined to this central region. it isn't bounded by a membrane. it isn't bounded by a membrane. it is visibly distinct from the rest of the cell interior. it is visibly distinct from the rest of the cell interior.

10. Ribosomes Ribosomes give the cytoplasm of bacteria a granular appearance. Ribosomes give the cytoplasm of bacteria a granular appearance. Though smaller than the ribosomes in eukaryotic cells. Though smaller than the ribosomes in eukaryotic cells. these inclusions have a similar function production of proteins. these inclusions have a similar function production of proteins.

11. storage granules Nutrients and reserves may be stored in the cytoplasm in the form of glycogen, lipids etc., Nutrients and reserves may be stored in the cytoplasm in the form of glycogen, lipids etc.,

12. Endospore Some bacteria form spores Some bacteria form spores that are highly resistant to drought, high temperature and other environmental hazards. that are highly resistant to drought, high temperature and other environmental hazards. Once the hazard is removed, the spore germinates to create a new population. Once the hazard is removed, the spore germinates to create a new population.

13. Surface Structure Beginning from the outermost structure and moving inward, bacteria have some or all of the following structures: Beginning from the outermost structure and moving inward, bacteria have some or all of the following structures: capsule capsule outer membrane outer membrane cell wall cell wall plasma membrane plasma membrane

14. Capsule This layer (polysaccharide ) protects the bacterial cell. This layer (polysaccharide ) protects the bacterial cell. It serves as a barrier against phagocytosis by white blood cells (WBC). It serves as a barrier against phagocytosis by white blood cells (WBC).

15. cell wall the cell wall maintains the overall shape of a bacterial cell. the cell wall maintains the overall shape of a bacterial cell. The three primary shapes in bacteria are coccus (spherical), bacillus (rod-shaped) and spirillum (spiral). The three primary shapes in bacteria are coccus (spherical), bacillus (rod-shaped) and spirillum (spiral).*****Imp Mycoplasma are bacteria that have no cell wall and therefore have no definite shape. Mycoplasma are bacteria that have no cell wall and therefore have no definite shape.

16. plasma membrane This is a lipid bilayer much like the cytoplasmic (plasma) membrane of other cells. This is a lipid bilayer much like the cytoplasmic (plasma) membrane of other cells. primarily responsible for transport of ions, nutrients and waste across the membrane. primarily responsible for transport of ions, nutrients and waste across the membrane.

17. Appendages - Pili Flagella Flagella

18. Pili These are hollow, hairlike structures made of protein allow bacteria to attach to other cells. These are hollow, hairlike structures made of protein allow bacteria to attach to other cells. A specialized pilus, the sex pilus, allows the transfer from one bacterial cell to another. A specialized pilus, the sex pilus, allows the transfer from one bacterial cell to another. Pili (sing., pilus) are also called fimbriae (sing., fimbria). Pili (sing., pilus) are also called fimbriae (sing., fimbria).

19. Flagella The purpose of flagella (sing., flagellum) is motility. The purpose of flagella (sing., flagellum) is motility. Bacteria may have one, a few, or many flagella in different positions on the cell. Bacteria may have one, a few, or many flagella in different positions on the cell.

20. Summary-1 1. prokaryotes include kingdoms of simple bacteria. 2. molecules surrounded by a membrane and cell wall 3. lack membrane enclosed "organelles“.

21. Summary-2 Internal structures Internal structures -Nucleoid -Nucleoid –Ribosome's –Storage granules –Endospore

22. Summary-3