The Discovery of the Cell 7-1 Life Is Cellular Review the cell in relation to: - Its definition - The origin of life - The characteristics of life - The hierarchy of biological organization - The science of biology What did the discovery of the cell as the basic unit of life depend on? Nucleus (not all) Cytoplasm (Cytosol + Organelles) Plasma Membrane Label as much as you can of this white blood cell (3 major components). 1
Identify this scientist. (Robert Hooke) The Discovery of the Cell Identify the material in the micrograph. What did he observe in 1665? How? What did he establish? Early Microscopes Identify this scientist. (Anton van Leeuwenhoek) What did he observe in 1670? What did he establish? What did he call them? What do we call them today? 2
The Development Of Cell Theory The Discovery of the Cell Identify this scientist. (Matthias Schleiden) What did he observe in 1838? How? What did he establish? Identify this scientist. (Theodor Schwann) What did he observe in 1839? How? What did he establish? Identify this scientist. (Rudolph Virchow) What did he observe in 1855? How? What did he establish? (Omnis cellula e cellula) What are the 3 postulates of cell theory? 3
Types Of Microscopes Exploring the Cell What are the two major classes of microscopes? Which type produces greater resolution and magnification? How many times? What is the drawback for this type of microscope? Identify, compare & contrast the two types of microscopes that created these micrographs. 4
Types Of Microscopes Exploring the Cell Which of the two major classes of microscopes produced the micrograph on the left? What is it called? What does it use that is different? Which of the two major classes of microscopes produced the micrograph on the right? What is it called? What does it use that is different? HeLa Cells (Henrietta Lacks, 1951) 5
Note the relationship between this chart and the hierarchy of biological organization. Human height 1m Length of some nerve and muscle cells 0.1 m Chicken egg Identify and label each different unit of measure along the scale. Unaided eye How small are cells? 10 m 1 cm Frog egg Define each using scientific notation. Now that you have this knowledge, note the size ranges occupied by the two major cell types. 100 µm Most plant and animal cells 10 µm Nucleus Most bacteria 1 µm 100 nm Mitochondrion Smallest bacteria Viruses Ribosomes 10 nm Electron microscope What is the mathematical equivalent of each unit relative to the base unit? (How many are there in one base unit?) Light microscope What is the base unit for all of these units? 1 mm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms 6
Two Major Cell Types What are three structural (and functional) components that all living cells share? Create a two column table that compares the two major cell types. Include the following: 1) Column labels identifying each cell type 2) A labeled drawing of each cell type 3) Compare the following: Nucleus, Organelles, Size range, When evolved, Kingdoms of each. Prokaryotes were first and set up the system we all live within! 7
The top diagram represents a heterotrophic prokaryote. The bottom, an autotrophic prokaryote. Label the diagrams with BOTH structure & function. Prokaryote S & F Simple cells can perform all basic life funcitons! 8
7-3 Cell Boundaries Diffusion Through Cell Boundaries What is an aqueous solution? What is the cytosol? Study the diagram... Identify the component of blood that the cells are bathed in? What is it? How do the environments inside and outside the cells compare? (They are both...) What is the boundary that separates these environments? Is this true for all cells? Is it only a boundary, or does it do more? Life is in aqueous solution! 9
Diffusion Through Cell Boundaries Measuring Concentration Review Define the mixture known as a solution. Name & define the two components of a solution? In this example, identify which is which? Therefore what kind of solution is this? Explain why water is the universal solvent and dissolves sodium chloride so easily? Define the concentration ([ ]) of a solution? What makes one solution more concentrated relative to another? What is a dilute solution? How is concentration measured and calculated? Note: There are many ways concentration can be expressed. All indicate the relative amount of solute in solvent. Example Calculations 100 g NaCl in 1 L H2O = g/l 10 g NaCl in 100 ml H2O = g/ml or g/l since there are 1000 ml in a L Mass or Number of Particles/Volume 10
Diffusion Through Cell Boundaries Diffusion Red Dye Water Time Describe what the person in the diagram is doing. How would you describe the concentration of dye molecules (particles) in the area where they are initially added relative to the rest of the container? Define concentration gradient ([ ]g) and relate it to this example. As time passes, describe what happens to the dye molecules relative to the [ ] g. Define diffusion and relate it to this example. Describe the distribution of dye molecules at the end of this example. Define equilibrium and relate it to this example. Particles diffuse along their [ ]g to equilibrium! 11
Review Identify three major components of ALL cells. Define plasma membrane. Define cell wall. The Cell Membrane Cells of which Kingdoms have a cell wall. Differentiate between the plasma membrane and cell wall in terms of function. The plasma membrane is a selective barrier! 12
The Plasma Membrane What are cells mostly made of? Study the top left diagram. What molecule is this? Relate the space-filling model to the symbolic model and identify the two major regions. Define and differentiate between hydrophilic and hydrophobic. Observe the liposome diagram. When do these form? What do they resemble? The middle diagram is a magnified view of the barrier surrounding the liposome. Define phospholipid bilayer. Explain why phospholipid bilayers form when phospholipid molecules are in aqueous solution. 13 Cell membranes are phospholipid bilayers!
Passive Diffusion Define permeable in relation to the membrane and solute. Extracellular Plasma Time Define and Intracellular differentiate between extracellular and intracellular. What is the first pane of the diagram showing in terms of the distribution of solute across the membrane? (What do we call this?) Describe how the distribution of solute is changing using specific vocabulary. Describe the final distribution of solute and explain why the arrows are now pointing in both directions. Define dynamic equilibrium. Passive diffusion REQUIRES NO CELLULAR ENERGY! 14
Osmosis 100ml 100ml Concentrated sugar solution 125ml 75ml Dilute sugar solution (100ml) Time Sugar molecules (Water molecules not shown) Semipermeable Membrane Movement of water Differentiate between impermeable, semipermeable, and selectively permeable. Determine what the membrane is impermeable and permeable to. Are the solute particles the only particles in solution? Explain! Explain how the diagram shows the concentration difference between solutions. What is the relationship between the number of solute particles and the number of free water molecules in solution? Explain the meaning of free. Identify and label all concentration gradients in this example. Will all molecules in this example diffuse along their concentration gradient? Define osmosis. Define tonicity. Differentiate between hyper, hypo and isotonic. Osmosis is the diffusion of water through membranes! 15
Osmosis Compare this example with the previous one. What is the significant difference? Define osmotic pressure. Differentiate between the two sides in terms of solute concentration, free water molecules, and tonicity. Label them! Describe how the two sides of a semipermeable membrane are affected differently. Realize the consequence of this for cells! Osmotic pressure is dangerous! 16
Identify the animal cell in this example. Identify the two structural differences between animal and plant cells. Relate the hypertonic case to solute concentration and free water molecules. Osmosis Describe, explain, and differentiate the hypertonic result for each cell type. Define plasmolysis. Define crenation. Relate the hypotonic case to solute concentration and free water molecules. Describe, explain, and differentiate the hypotonic result for each cell type. Define cytolysis. Define turgor. Which osmotic environment is actually preferred by plant cells and why? Plasmolysis Cytolysis In terms of tonicity, what do your cells prefer? Define interstitial fluid. Define osmoregulation. Relate this to homeostasis. What organ system maintains your osmotic balance? What would happen to your blood cells if your hospital IV solution is too concentrated? Too dilute? Osmotic balance is crucial! 17
Cell Membrane Constituents Outside of cell Cell membrane Proteins Carbohydrate chains Inside of cell (cytoplasm) Protein Lipid bilayer channel Define the fluid mosaic model of the plasma membrane. Molecules from which class of organic compound are attached to some proteins? What is the function of these glycoproteins? What other function can membrane proteins perform? The plasma membrane phospholipid bilayer alone forms which type of barrier? What effect do certain proteins embedded in the bilayer have on permeability? Identify the protein in this diagram involved in membrane transport. What other types of transport proteins are there? Membrane function depends on proteins! 18
What are three characteristics of solute particles that determine whether they are membrane permeable? Define passive transport. Differentiate between channel and carrier proteins. Facilitated diffusion requires what? Define facilitated diffusion. What is a gated channel? What are two ways gates can be opened? Facilitated Diffusion Glucose molecules Protein channel or carrier A passive form of carrier transport! 19
Active Transport Define active transport. Active transport does not require what? Molecule or ion to be carried Active transport proteins are also known Low Solute as what? Concentration The energy for active transport is supplied by what? What does active transport allow cells to do that passive transport does not? PUMP High Solute Concentration Use ATP to pump particles against their [ ]g! 20
What is the direction of the [Na+]g? [K+]? g If membrane permeable, which direction would each type of ion diffuse? Is the phospholipid bilayer permeable to these ions? Why? What direction are both these ions being pumped relative to their [ ]g? What two things indicate that this is active transport? Explain! Describe what the pump does in terms of the kind of ions, number of ions and the direction pumped. Explain how this pump would result in a difference in charge across the membrane. Define electrogenic pump. Active Transport [Na+]g [K+]g A ubiquitous electrogenic pump! 21
Active Transport Bulk Transport cell drinking cell eating Highly specific! Define bulk transport. Explain why it is a form of active transport. Define and translate endocytosis. Define, translate and describe phagocytosis. Define, translate and describe pinocytosis. Define and describe receptor-mediated endocytosis. Compare and contrast these three forms of endocytosis. Predict the fate of each vacuole/vesicle contents. Plasma membrane actively engulfs large quantities! 22
Active Transport Bulk Transport Define, translate, and describe exocytosis. When the cell is specialized to manufacture and release compounds through exocytosis, what is the process known as? Think of one example. What classes of compounds might the ER produce for exocytosis? What is the function of the Golgi apparatus in this example? This series of organelles are part of what organelle system? Predict the fate of the secretory vesicle membrane. Plasma membrane actively releases large quantities! 23
Unicellular Organisms The Diversity of Cellular Life Identify this organism. How do you know? Is it microscopic or macroscopic? How do you know? Is it unicellular or multicellular? How do you know? Because they are microscopic, what are unicellular organisms collectively known as? Which Kingdoms include unicellular organisms? What kind of organisms dominate life on Earth? Colorized TEM We live within the system created and run by microbes! 24
Multicellular Organisms The Diversity of Cellular Life Which Kingdoms include multicellular organisms? What is this a photo of? What is happening in this photo? What would have been different a short time before this photo was taken? How do multicellular organisms start out? Predict what will happen next, and continue, considering the number of cells, differentiation and specialization. Explain how the diversity of multicellular organisms stems from the cellular level. We all developed from one cell that divided and differentiated! 25
Differentiation & Specialization Multicellular Organisms Define cell differentiation. Define cell specialization. Identify each of these specialized cells. Determine the function of each of these specialized cells. We are made up of over 200 specialized cell types! 26
Differentiation & Specialization Multicellular Organisms Identify this micrograph. What are the small openings called? What are the two cells on either side of each opening called? What are these cells specialized to do? What life process does this regulate in the plant? All multicellular organisms have specialized cells! 27
7-4 The Diversity of Cellular Life Muscle cell Level & Definition Levels Of Multicellular Organization Smooth muscle tissue Level & Definition Stomach Digestive system Level & Definition Level & Definition Examples Examples Examples Examples 1. 1. 1. 1. 2. 2. 2. 2. 3. 3. 3. 3. 4. 4. 4. 4. 28