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Cellular Theory and Evolution

Cellular Theory and Evolution. The Cell Theory. All cells come from pre-existing cells (Virchow) All plants and animals are composed of cells (Schleidan and Schwann) Now with more microscopic knowledge of the other three kindgoms, we can say that cells are the fundamental units life.

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Cellular Theory and Evolution

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  1. Cellular Theory and Evolution

  2. The Cell Theory • All cells come from pre-existing cells (Virchow) • All plants and animals are composed of cells (Schleidan and Schwann) • Now with more microscopic knowledge of the other three kindgoms, we can say that cells are the fundamental units life.

  3. Cellular Evolution • The original cellular life was heterotrophic and prokaryotic. (Monera) • Then, cells became larger and through endosymbiosis incorporated the mitochondrion and chloroplast. (Protista) • Finally, cells joined to form multicellular organisms. (Plantae, Animalia, Fungi)

  4. Prokaryotic Characteristics • Single circular chromosome • Plasma membrane but no nuclear membrane • Energy production is a function of the cell • Featureless cytoplasm • No permanent cytoskeleton • Cell wall of peptidoglycan (amino acid/sugar) • No endosymbionts • Metabolic diversity • Intracellular transport relies on diffusion

  5. Eukaryotic Characteristics • Large in size (volume 1000 >than prokaryote) • Energy production function of organelles • Cytomembrane system • Organelles of movement • Larger genome, with interrupted genes, non-coding regions of DNA • Cytoskeleton integrated with membrane and cytoplasm

  6. CELLULARSIGNAL TRANSDUCTION The bacterial flagella

  7. Flagella Motor: Clockwise • Spins Counter Clockwise • Multiple flagella spiral into a single tail causing the bacteria to move in a straight line

  8. Flagella Motor: Counter Clockwise • Spins Clockwise • The flagella unfurl and stroke independently causing the bacteria to move more randomly

  9. Movement in the Environment • By adjusting the proportion of the two types of movement described, a bacterium can direct itself in its environment

  10. Bacterial Senses: Receptors • The Escherichia coli has five protein membrane receptors that bind particular receptors important to their life. • One example is the Tar Receptor which binds the amino acid “aspartate”.

  11. The Tar Receptor • The Tar receptor has two functional components. • The sensory binding site for aspartate lies outside the inner membrane. • The receptor spans the membrane with a mobile helical segment lying in the cytoplasm acting as a swinging piston.

  12. Intracellular Communication • The swinging piston prompts Chemotaxis (Che) W to activate the kinase CheA. • CheA transfers a phosphate group to CheY, which causes the flagella rotor to change to spinning clockwise

  13. Flagella Assembly • Flagella Reversal • Flagella Experiment

  14. Bibliography • Debra Niehoff (2005) The Language of Life: How Cells Communicate in Health and Disease, Joseph Henry Press, Washington, D.C. • Protonic Nanomachine Project & The Laboratories for Nanobiology (Information) • Flagella and ID Websites

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