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1.2 Prokaryotic Cells

1.2 Prokaryotic Cells. IB Biology. Essential Idea. Eukaryotes have a much more complex cell structure than prokaryotes. Prokaryotic Cells. First organisms to evolve on Earth 3.5 billion years ago cyanobacteria Simplest cell structure Eubacteria and Archaea. Origin of Life.

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1.2 Prokaryotic Cells

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  1. 1.2 Prokaryotic Cells IB Biology

  2. Essential Idea • Eukaryotes have a much more complex cell structure than prokaryotes

  3. Prokaryotic Cells • First organisms to evolve on Earth • 3.5 billion years ago • cyanobacteria • Simplest cell structure • Eubacteria and Archaea

  4. Origin of Life • Miller-Urey Experiment • Stimulated pre-biotic life conditions in the lab for 1 week • Ammonia (NH3) • Methane (CH4) • Hydrogen (H2) • Water (H2O) • Spark of electricity (simulate lightning)

  5. Origin of Life • Experiment Results • Organic compounds found • Amino acids which make up proteins of living things • Experiment not supported today other than to show that life can arise from a chemical origin • Recall: This is evidence supporting the cell theory “all cells come from preexisting cells”

  6. DVD: Cosmos, Carl Sagan • 1980s TV series narrated and produced by Carl Sagan • He was an astronomer, cosmologist, astrophysicist • Episode 2: Chapter 10 • One Voice in the Cosmic Fugue • Time: 46-52 min

  7. No true nucleus Heterotrophs or autotrophs Most have cell wall with peptidoglycan Live everywhere Eg. Bacteria cyanobacteria No true nucleus Heterotrophs Cell wall with no peptidoglycan Live in extreme environments Salt (halophiles) Heat (thermophiles) Methane (methanogens) Prokaryotes: Eubacteria vs. Archaea

  8. Prokaryote Properties • Small size • Unicellular • One cell must carry out all the functions of life • Found everywhere • Can live in various extreme environments • Found in soil, water, volcanoes, intestines and skin

  9. Metabolic Properties • 1.Fermentation • Convert lactose (sugar) into lactic acid for yogurt production • 2. Photosynthesis • Blue-green bacteria produce their own food • 3. Nitrogen Fixation • Convert nitrogen from air into nitrogen compounds useful in soil

  10. Prokaryotic Structures • No nucleus • No mitochondria • No membrane bound organelles

  11. Found in your gut Escherichia coli Scanning Electron Microscope Transmission Electron Microscope

  12. CELL MEMBRANE CYTOPLASM E. Coli Micrograph • Cell wall • Carbohydrate and protein • Protection • Maintains shape • Prevent bursting • Cell (plasma) membrane • Phospholipid bilayer • Partially permeable controls what enters and exits the cell

  13. CELL MEMBRANE CYTOPLASM • Cytoplasm • Fluid, gel-like • Contains free floating molecules • Enzymes, ribosomes • Location of chemical reactions of metabolism • Nucleiod • Small amount of circular DNA with no protein • Controls cell activities • Ribosomes (70s) • Make proteins from RNA messages

  14. FLAGELLA PILI Motion • Flagella • Protein propeller • Attached to cell wall • Use energy to move cell • Not very flexible • Pili • Protein filaments attached to cell wall • Pulled in or pushed out • Used to adhere or “stick” to other bacteria cells to exchange DNA • conjugation

  15. Reproduction • Binary Fission • Bacterium replicates its DNA and then divides the cytoplasm • One copy of DNA on each side Cytokinesis

  16. Identify Prokaryotic Structures ribosome nucleiod Cell membrane Cell wall cytoplasm

  17. IB Objectives • Prokaryotes have a simple cell structure without compartmentalization. • Electron microscopes have a much higher resolution than light microscopes. • Application: Prokaryotes divide by binary fission. • Skill: Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.

  18. Tasks • Bacteria worksheet

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