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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 and chemistry again!) • so physics and chemistry 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 and polar) Hydrophobic (not water loving or polar) Hydrophilic (water loving and polar) 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. Question In the following diagram, which letter identifies the cytoplasm? A. B. C. D. E. None of the above

  21. Question In the following diagram, which of the arrows indicates the lipid portion of the membrane? A. B. C. D.

  22. 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)

  23. 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!)

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

  25. Size of Eukaryote vs. Prokaryote

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

  27. 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 _____?

  28. 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 …!

  29. 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!

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

  31. Now the Granola Bar

  32. 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)

  33. 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)

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

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

  36. Question Energy is a commodity in all living systems. The principles governing the use of energy in plants, animals and microbes are consistent with ____. A. The Law of energy efficacy B. Biochemical Law of energy transfer C. First and second laws of thermodynamics D. All of the above

  37. Question The carbohydrate (CH2O) is the energy rich product of photosynthesis in plants. The “energy richness’ is simply another way of stating that ___. A. Energy transductions in plants conform to the 2nd Law of Thermodynamics B. Energy is stored in the covalent bonds between carbon atoms C. Energy is the sole product of photosynthesis D. Energy is the ATP commodity in all cellular biochemistry

  38. Question Mitosis and meiosis are two dissimilar processes in plants and animals and yet they share the same underlying characteristic of living systems which is one of _____. A. Information copying B. Energy utilization C. Gender identification D. A and B above E. B and C above

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