1. BIOLOGY 11 IB 2.2: PROKARYOTIC CELLS

2. TWO GROUPS OF CELLS Cells can be categorized into two groups – prokaryotes and eukaryotes. Difference: Eukaryotic cells have membrane bound organelles whereas the organelles of prokaryotic cells are not surrounded by membranes. Prokaryotic cells include bacteria. Eukaryotic cells include plant and animal cells.

3. ASSESSMENT STATEMENTS 2.2.1 Draw and label a diagram of the ultrastructure of Esherichia coli (E. coli) as an example of a prokaryote 2.2.2Annotate the diagram with the functions of each named structure 2.2.3Identify structures from 2.2.1 in electron micrographs of E. coli 2.2.4State that prokaryotic cells divide by binary fission

4. PROKARYOTIC CELLS ‘Prokaryotic’ comes from Greek pro meaning before, and karyon meaning ‘kernel’, referring to the nucleus The general size of a prokaryotic cell is about 1-2 um. There is no true nucleus with a nuclear membrane The ribosomes are smaller than eukaryotic cells The slime capsule is used as a means of attachment to a surface Only flagellate bacteria have the flagellum Plasmids are very small circular pieces of DNA that maybe transferred from one bacteria to another.

5. PROKARYOTIC METABOLISM Bacteria have a large range of different metabolic reactions, far more than in eukaryotes, who are confined to just respiration or photosynthesis 1.Fermentation: Sometimes these bacteria oxidize organic molecules like glucose. In many instances they metabolize as far as lactic acid or alcohol molecules making them useful to the fermentation industry

6. 2.Photosynthesis: Many bacteria are photosynthetic and use the same process of photosynthesis as plants. These phototropic bacteria were some of the earliest forms of life on the planet, and their metabolic reactions increased the oxygen content of the atmosphere from 1% to 20% 2.Nitrogen fixing: Some bacteria obtain their energy by oxidizing inorganic compounds like ammonia, nitrite, methane, or hydrogen sulphide. These bacteria use a variety of unusual metabolic reactions and many are able to synthesize carbohydrates from carbon dioxide – the chemosynthetic bacteria

7. BINARY FISSION Prokaryotic cells divide by binary fission. This is an asexual method of reproduction in which a cell divides into two same sized cells. The cells are genetically identical and form the basis of a reproductive clone.

8. Binary fission is not the same as mitosis, because there is no condensation of genetic material and no spindle formation In the process of binary fission: The circular DNA is copied in response to a replication signal The two DNA loops attach to the membrane The membrane elongates and pinches off (cytokinesis) forming two separate cells