Prokaryotes - PowerPoint PPT Presentation

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by daniel ospina and nicolle rodriguez n.
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Prokaryotes

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  1. By: Daniel Ospina and Nicolle Rodriguez Prokaryotes

  2. Very similar to eukaryotes. • Live in very harsh conditions. • They do not cause diseases. • Unlike eubacteria their cell wall is composed out of glycoproteins and polysaccharides. • Glycoproteins- a group of conjugated proteins that have a carbohydrate as a non protein compound Types of Prokaryotes • Larger of the kingdoms. They can live almost everywhere and are surrounded by a cell wall. • There cell wall contains peptidoglycan. • Peptidoglycan-A polymer in cell walls of prokaryotes made up of polysaccharide and peptide chains in a network. Eubacteria Archaebacteria

  3. Autotrophs Organisms that can make their own food

  4. Photoautotrophs • Carry out photosynthesis like plants. • Are found in areas with a lot of light. • Example: Cyanobacteria • They contain chlorophyll and our found all over the world in areas with plenty of light.

  5. Chemoautotrophs • Do not do photosynthesis • Get their energy from inorganic molecules and chemical reactions such as those Involving ammonia, sulfur, or iron. • Examples would be common soil bacteria

  6. Heterotrophs Organisms that cannot make their own food

  7. Photoheterotrophs • They are photosynthetic meaning they use the sun for energy. • They use organic compounds as nutrients • Mixture of an autotroph and heterotroph

  8. Obligate aerobes V.S. Obligate anaerobes • Organisms that need a constant supply of oxygen like us. • Go through the process of cellular respiration. • Organism that live without oxygen and can be harmed by it. • Examples of these are bacteria such as the Clostridium botulinum which grows in the soil. Obligate aerobes Obligate anaerobes

  9. Facultative anaerobes • They do not require oxygen to live but are not harmed by it either. • They can switch between cellular respiration and fermentation making them very versatile and allowing them to grow anywhere. • Certain fungi such as yeast are facultative anaerobes.

  10. Prokaryotes are small and its hard to notice there characteristics. Prokaryotes are characterized by their shapes, the chemical nature of their cell walls, the ways they move, and the ways they obtain energy. Characteristics of Prokaryotes

  11. Shapes of Prokaryotes • Prokaryotes usually come in three distinct and basic shapes. • Rod-shaped prokaryotes are called Bacilli (singular: bacillus) • Spherically-shaped prokaryotes are called cocci (singular: coccus) • Spiral/corkscrew-shaped prokaryotes are called Spirilla (singular: spirillum)

  12. Cell Walls • There are two different cell walls in eubacteria. To tell them apart, scientists use a method called Gram staining. • The Gram stain consists of two dyes: violet and red. The different cell walls will react in their own way to the stain. • Prokaryotes with cell walls that contain a lot of peptidoglycan would absorb more of the violet dye. These are called Gram-positive. • Prokaryotes with an extra layer of lipids and carbohydrates that absorb mostly the red dye are called Gram-negative.

  13. Movement • Prokaryotes move in different ways. • Some use flagella, whiplike structures, to propel themselves. • Others lash, snake, or spiral forward. • Some glide over slimelike materials that they secrete. • Many do not move at all.

  14. Growth and Reproduction • Under favorable conditions, prokaryotes could grow and divide very quickly. They could divide as quickly as every 20 minutes! • Most prokaryotes reproduce using binary fission, an asexual form of reproduction in which the cell copies its DNA and then divides itself in half. This works much like regular cell division. • Other prokaryotes exchange genetic information by forming a hollow “bridge” that allows genes to move from one cell to another. This is called conjugation. • Other prokaryotes form spores that later germinate and form entirely new cells. This ability helps many prokaryotes survive in harsh conditions.