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Week 12: The Cell as the Functional Unit

Week 12: The Cell as the Functional Unit. Characteristics of cells Metabolism Reproduction: mitosis and meiosis (text) Recapitulation. Hierarchical Nature of Living Systems. Community Population Organism Organ

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Week 12: The Cell as the Functional Unit

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  1. Week 12: The Cell as the Functional Unit • Characteristics of cells • Metabolism • Reproduction: mitosis and meiosis (text) • Recapitulation

  2. Hierarchical Nature of Living Systems Community Population Organism Organ Tissue Cell Organelles Macromolecules Atoms

  3. Structural and Functional Characteristics of Cells • Cells as the physical infrastructure • Cell membranes: gate keeper of outflow and inflow of materials • Water: medium of cell’s biochemistry • Compartmentation via organelles: a good thing! • Major types of cells (see text)

  4. Cells as the Physical Infrastructure • Cell theory • All organisms composed of cells • Cells as smallest unit of organization exhibiting all characteristics of life (e.g., irritability, reproduction, energy) • Structure Cell Membrane Nucleus Cytoplasm Organelles

  5. Size of Cells Relative to Other Features in the Sciences 10-10m 10-5m 10+3m ~Five orders of magnitude (105) larger than atoms and visible with light microscope

  6. General Features of a Cell • Size correlated with function • Upper limit: 0.00001 m (1 x 10-5 m) • Distance from interior to exterior: critical • Over 1 x 10-5 m: nonfunctional • Efficacyof transport/diffusion (diffusion … physics again!) • so physics determines upper limit of the cell

  7. Structural and Functional Characteristics of Cells • Cells as the physical infrastructure • Cell membranes: gate keeper of outflow and inflow of materials – stop … what is a gate? • Water: medium of cell’s biochemistry • Compartmentation via organelles: a good thing! • Major types of cells

  8. Membranes: Structure • Principal structural components (N=2) • Lipid • Phosphate group (PO4) • Lipid bilayer at the molecular level • Functional property: contrasting chemical characteristics of the two layers Phosphate/ Glycerol (Hydrophilic - polar) Lipid/Fatty Acid (Hydrophobic – non-polar) Hydrophilic (water loving) Hydrophobic (not water loving) Hydrophilic (water loving) Lipid Bilayer

  9. Membranes: Structure • Lipid bilayer: “fluid membrane” with floating chunks of proteins and carbohydrates (e.g., icebergs) Lipid Bilayer Protein Chunk

  10. The Cell as the Functional Unit • Characteristics of cells • Start with membranes • Metabolism • Reproduction: mitosis and meiosis (text) • Recapitulation

  11. Membranes: from Lipid Bilayer to Functional Properties • Example of hierarchy theory and emergent properties • “Parts”: lipid, phosphate, proteins, carbohydrates • When combined: unusual/unexpected properties = emergent properties • Selective permeability (text and lecture) • Active transport (text) • Signaling: cell-to-cell communication (text)

  12. Transport through Membrane: Selective Permeability

  13. Signaling in/on Membranes Swine Flu Cystic Fibrosis Allergies http://www.youtube.com/watch?v=GW0lqf4Fqpg

  14. The Cell as the Functional Unit • Characteristics of cells • Water medium • Metabolism • Reproduction: mitosis and meiosis (text) • Recapitulation

  15. Water: Medium for Biochemistry(back to chemistry!) • Role of water (H2O) • Liquid medium for cell • Physical properties (e.g., polarity, phases) • Chemical properties (e.g., pH, liquid solution) • Exquisite and unique properties of H2O • Importance in cell metabolism: liquid phase chemistry and pH • Imagine a cell’s functioning in a medium other than liquid water (say … water in a gas phase or a solid)

  16. The Cell as the Functional Unit • Characteristics of cells • Compartmentation • Metabolism • Reproduction: mitosis and meiosis (text) • Recapitulation

  17. General Cell Structures: Compartmentation

  18. Principle of Compartmentation • Cells are compartmentalized • Elaborate and organized infrastructure • Analogy to a dorm • Corridors as endoplasmic reticulum • Rooms as organelles • Consequence of not being compartmentalized … disorder! • Function of individual organelles (text)

  19. Compartmentation: Animal cell

  20. Structural and Functional Characteristics of Cells • Cells as the physical infrastructure • Cell membranes: gate keeper of outflow and inflow of materials • Water: medium of cell’s biochemistry • Compartmentation via organelles: a good thing! • Major types of cells (see text)

  21. Cell Types • Prokaryotes • No nucleus • No mitochondria, chloroplasts, Golgi or endoplasmic reticulum • DNA, enzymes, metabolize, etc. • Example: bacteria • Eukaryotes • Nucleus and all the organelles • Plant eukaryotes – same except • Chloroplast for photosynthesis and cell wall • Animal eukaryotes (this is you!)

  22. Prokaryote: Bacteria • Flagella • Information • Capsule • Plasma Membrane • Cytoplasm • Cell Wall • Spores

  23. Size of Eukaryote vs. Prokaryote

  24. The Cell as the Functional Unit • Characteristics of cells • Metabolism (all about carbon-carbon bonds) • Reproduction: mitosis and meiosis • Recapitulation

  25. Energy Utilization • Three related activities: acquisition, utilization, and storage • Energy Acquisition • Energy capture (autotrophs; heterotrophs) • First law of Thermodynamics • Energy utilization • Laws of Thermodynamics (1st and 2nd laws) • ATP (adenosine triphosphate) and ADP (adenosine diphosphate) • Energy storage • Chemical bonds (C-C covalent bonds) • Carbohydrates, glycogen and lipids • In humans and other animals, storage as _____?

  26. The Cell’s Energy Currency: Analogy to Legos! • Adenosine triphosphate (ATP … high energy) • Adenosine diphosphate (ADP … low energy) • Structure • 3 or 2 phosphate groups • Sugar molecule • Function • Removal of phosphate group source of energy • Currency analogy in economy • Last 5 seconds in your body: trillions of ATP to ADP conversions and back again and again and again …!

  27. Cell’s Energy Currency Biosynthesis = construction of high energy carbon molecules Catabolism = deconstruction of high energy carbon molecules ADP Biosynthesis/Anabolism Catabolism ATP Remember the analogy to Legos!

  28. Photosynthesis • Photosynthesis • Convert sunlight to chemical energy (1st Law of Thermodynamics) • Process (building high energy carbon molecules) • Energy + CO2 + H2O  Carbohydrate + O2 Carbon - Carbon

  29. Now the Granola Bar

  30. Energy and the Granola Bar • First Law of Thermodynamics • Second Law of Thermodynamics (think ecology) • Chemistry of bonds (energy stored – First law of Thermodynamics) • Uniqueness of carbon atom’s bonding (covalent) • Immediate energy currency in cells via ATP and ADP • Release of some energy as heat (Second Law of Thermodynamics)

  31. Universality of Reproduction: How the Cell Achieves this Feat • Reproduction: regenerative process of making new organisms (not necessarily copies) • Methods • Sexual • Asexual (microbes; cell division/mitosis) • Examples • Siblings • Geranium plants • Dolly (the sheep)

  32. Reproduction in general Cell to cell reproduction Information copying (DNA) Reproduction: Mitosis (Text)

  33. The Cell as the Functional Unit • Characteristics of cells • Metabolism • Reproduction: mitosis • Recapitulation

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