1. PROKARYOTIC CELLS By Tibor Cemicky

2. 2 Main Types of Cells Prokaryotic Cells = Primitive Cells Eukaryotic Cells = much more complex Animal / Plant Cells

3. What are Prokaryotic Cells? Cells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei) All Bacteria, Achaea and Cyanobacteria are prokaryotic organisms Archaea: Haladaptatus Cyanobacteria: Fischerella Bacteria: Streptococcus

4. Structure of a Prokaryotic Cell Capsule: Secretion of sticky substances that form protective layer outside of the cell wall. Enables the organisms to adhere to their substrate and provide additional protection Cell Wall: Protects the cell from outer damage or bursting if internal pressure of the cell is high Plasma Membrane: Controls entry and exit of substances in or out of the cell (diffusion) Cytoplasm: Contains enzymes that catalyze (speed up) the chemical reaction of metabolism Pili: Protects cell wall, can be used to pull cells together or attach to surfaces Flagellum: used for locomotion (movement) Nucleoid: Region where the circular chromosome (DNA) is located Ribosomes: Only ‘organelles’ in a prokaryotic cell - Produce protein

5. Prokaryotic Cell vs. Eukaryotic Cells Prokaryotic CellsEukaryotic cells small cellslarger cells always unicellularoften multicellular no nucleus or any membrane-bound organelles always have nucleus and other membrane-bound organelles DNA is circular, without proteinsDNA is linear and associated with proteins to form chromatin ribosomes are small (70S)ribosomes are large (80S) no cytoskeleton (controversial)always has a cytoskeleton cell division is by binary fissioncell division is by mitosis or meiosis reproduction is always asexualreproduction is asexual or sexual

6. Reproduction ALL prokaryotic organism reproduce by binary fission Binary fission is the form of asexual reproduction and cell division. It is the division of a cell into two parts and each has the potential to grow to the size of the original cell.

7. Binary Fission Process: 1.DNA of the cell is replicated 2.Each circular strand of DNA then attaches to the plasma membrane 3.The cell elongates, causing the two chromosomes to separate 4.The plasma membrane then grows inward and splits the cell into two daughter cells 5.These 2 cells than both grow to the size of the parent cell...(Show a video)

8. Genetic Recombination Although Prokaryotes do not reproduce sexualy genetic recombination still occurs through these 3 proceses: Conjugation: A cell with DNA called F factor is able to replicate and inject a copy if it's DNA to another cell (without F factor) through a tube called a sex pilus. F factor may exist as a plasmid (independent DNA chromosome) or become integrated into the chromosome. If it is integrated into the chromosome, it may also transfer part of the chromosome.The DNA that is transferred is used to replace similar genes in the recipient cell. Transformation: occurs when a bacterium (plural of bacteria) picks up fragments of DNA released by dead bacteria or secreted by live bacteria. Transduction: occurs when viruses carry portions of bacterial DNA from one cell to another.

9. Bacteria: (differ in shape) –Round cells are called cocci –Rod-shaped cells are bacilli –Rigid, spiral-shaped cells are spirilla Classification of Prokaryotes coccibacillispirilla

10. Archaea: (differ in environment) –Methanogens are found in anaerobic environments (without oxygen) such as marshes and in the intestinal tracts of animals. They produce methane as a result of cellular respiration. –Halophiles are found in environments with high salt concentration such as the great salt lake or soil with a high salt concentration. –Thermophiles live in hot environments such as hot springs and hydrothermal vents. Classification of Prokaryotes

11. Cyanobacteria: (differ in shape) Unicellular: Filamentous: Classification of Prokaryotes - Gloeocapsa. Gloeocapsa is a unicellular cyanobacteria. The gelatinous material surrounding each cell causes the cells to stick together. - Oscillatoria cyanobacteria

12. 2 Types of Prokaryotic Organisms (food source): Autotrophs: They make their own food through photosynthesis or using energy from inorganic chemicals Heterotrophs: Heterotrophic prokaryotes feed on organic matter by secreting enzymes and absorbing the digested material. Prokaryotes - Organic Food

13. 2 Types of Autotrophs: Photosynthetic Prokaryotes: Prokaryotes that make organic food using energy from sunlight are photosynthetic Chemosynthetic Prokaryotes: Prokaryotes that make organic food by oxidizing high- energy inorganic compounds (hydrogen gas, ammonia, nitrites, and sulfides) Prokaryotes - Autotrophs

14. 3 Types of Heterotrophs: –Saprotrophic prokaryotes: They feed on nutrients that are tied up in the bodies of dead organisms. –Parasites: are prokaryotic organisms that live in close association with another species and benefits at its expense. Normally, the larger organism is not killed. –Mutualistic prokaryotes: They live in close association with another specie and both benefit as a result of the association. (For example, some nitrogen-fixing bacteria live on the roots of plants. They convert atmospheric nitrogen (N2) to a form that is usable by plants. In return plants provide the bacteria with carbohydrates.) Prokaryotes - Heterotrophs