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Do Now What are cells? Why do we need them? List different types of cells that you know of… Ch. 7: Cellular Structure and Function Objectives Describe how cells were discovered and named. Compare and contrast light microscopes vs. electron microscopes. Explain what is found in a basic cell. What are cells? Basic structural and functional unit of all living organisms! They come in all shapes and sizes Lets take a look… http://www.cellsalive.com/howbig.htm Cells! Egg cell How did we figure out cells even existed, what they looked like, what they do?... Nerve cell Bacteria cell Robert Hooke 1665- saw dead plant cells from cork, tree stems, roots and ferns using a light microscope Called them “cellulae” (small rooms) - reminded him of the cubicles or cells where monks live Anton Van Leeuwenhoek First person to observe living cells Made microscope with a magnification 10X that of Hooke’s- “Father of microscopes” Observed spirogyra and protists The “Cell Theory” Scientists expressed 3 main observations about cells: All living organisms are composed of one or more cells Cells are the basic units of structure and organization of all living organisms Cells come only from the reproduction of existing cells What do we use to look at cells? Cells were discovered using MICROSCOPES! Compound Light MicroscopesUses visible light to produce magnified image. Maximum = 1,000x magnification Electron MicroscopesSpecimen must be dead Use magnets and electrons Allows much greater magnification Ex: Transmission Electron = up to 500,000x Electron Microscopes Transmission Electron MicroscopeElectrons are sent through a specimen Scanning Electron MicroscopeElectrons are sent over the surface of a speciment. 3D image 100,000x magnification Microscope Activity!! How do Microscopes work? Use 2 lenses to magnify image of an object by focusing light or electrons Light passes through object Light Microscopes and Cell Stains 1st lens = objective - just above specimen – enlarges image of specimen 2nd lens = ocular lens Can produce clear images up to 1000 times Must use chemical dyes (stains) specific - reveal only certain compounds or structures Fluorescence – give of particular color of light when viewed under specific wavelengths of light Objectives List the different organelles of a cell. Explain the function of each organelle. Identify each organelle in a diagram of a cell. Basic Parts of any Cell DNA/RNA Needs some type of genetic information! Plasma membrane Cell’s outer boundary that acts as a barrier How big is cell in relation to things I know? Cell Size www.cellsalive.com 7.1 Cells, Prokaryote & Eukaryote I. All cells are either Prokaryotic or Eukaryotic ○ A. Prokaryote- “Before nucleus”, Bacteria, Has a nuclear region ● ● ● ● Simple structure Has Circular DNA Contains a plasma membrane and ribosomes Does not contain organelles EUKARYOTE ○ B. Eukaryote- “True nucleus”, has a membrane bound DNA containing organelle (nucleus) ● ● ● ● More complex structure Contains Plasma membrane Animal cells and plant cells -most other cells besides bacteria Contains organelles (mitochondria, nucleus, etc.) Basic Parts of any cell (cont.) Cytoplasm Region of cell that includes fluid, cytoskeleton and all organelles Control Center Contains a cell’s DNA Nucleus- membrane- bound structure in eukaryotes Nucleoid- region of DNA in prokaryotes Prokaryotic Cells… Do not have a distinct nucleus No membrane-bound organelles Ex: bacteria Many scientists think that prokaryotes are similar to the first EVER organisms on Earth Eukaryotic Cells… Contain a nucleus Contain membrane-bound organelles All multicellular organisms are Eukaryotic Ex: US, plants, animals, etc. (also some unicellular organisms like algae and yeast) Do Now!! Please take out your organelle packets!! The differences between animal and plant cells… http://www.youtube.com/watch?v=-zafJKbMPA8 Objectives Discuss the role of the plasma membrane. Identify the components of the plasma membrane and their functions. Define diffusion. So what does the plasma membrane do? Maintains an internal environment that is different from the external environment. Determines what molecules enter and exit the cell (homeostasis). Made of a phospholipid bilayer II. Phospholipid ○ A. Made of: Gylcerol, 2 fatty acid chains, and a phosphate group ○1. “Phospho”-Hydrophillic Polar (heads) ○2. “lipid”-Hydrophobic Non-polar (tails) C. Bilayer Water or other hydrophilic substances Fats (hydrophobic) Water or other hydrophilic substances Selective permeability Controls the movement of substances in and out of the cell Controls AMOUNT of substances entering and leaving the cell Fish net analogy Phospholipid Bilayer Structure of the plasma membrane Proteins: receptors, structure, transport Cholesterol: prevents tails from sticking Proteins and other components are embedded like a mosaic: “Fluid Mosaic Model” http://www.youtube.com/watch?v=Qqsf_UJcfBc Cholesterol Prevents fatty acid tails from sticking together Carbohydrates o Attached to proteins o Help cell identify chemical signals o ex: help disease-fighting cells recognize harmful cells Proteins Provide channels for transport Act as cell receptors (transmit signals) Provide structure Conclusion activity Do Now!! - Label the different parts What is the name of the entire structure? Objectives Define diffusion. Identify the conditions that effect the rate of diffusion. Explain facilitated diffusion. Compare and contrast active and passive transport. What is diffusion? Diffusion- movement of particles from area where there are many to area where there are fewer Movement of molecules from high concentration to low concentration by random motion (no energy required) High concentration Low concentration What is diffusion? Mixing continues until concentrations are the same in all areas Dynamic Equilibrium -continues movement but no NET overall change in concentration Explain what’s happening… Diffusion Video https://www.youtube.com/watch?v=VY0mZUDvbH4 Diffusion across the plasma membrane *Cells also need ions and small molecules to perform cellular functions (ex: ions and sugars) (ex: H2O, O2, CO2) T.P Large and/or ChargedTransport Protein Small and/or nonpolar molecules Diffusion of Water- OSMOSIS Water can move right through the phospholipids from high to low concentration Facilitated Diffusion Most substances cannot readily pass through the membrane Facilitated diffusion: Movement of materials across the plasma membrane using proteins Channel Proteins Carrier Proteins Types of Transport Proteins Channel Proteins Pores that allow charged ions to pass through the membrane Carrier Proteins Change shape to help molecules pass through the membrane Do Now!! What is diffusion? What do you think “passive” transport is? What do you think the difference is between passive and active transport? Objectives To explain active and passive transport. To understand what happens during osmosis. To compare and contrast hypertonic, hypotonic, and isotonic solutions. Passive Transport Movement of particles across the cell membrane without using energy Diffusion of Water Things that affect the speed of passive transport 1. Heat- Hotter faster 2. Size- Bigger slower 3. State of Matter Solid- Slow Liquid – Fast Gas- Fastest What is active transport? Molecules move usually in opposite direction of diffusion (Low concentration to high concentration = going against the flow) Carrier proteins help movement Requires ENERGY (ATP) Ex: Sodium potassium pump Potassium pumped in, sodium pumped out Osmosis Water always flows via osmosis from HIGH water concentration to LOW water concentration through a semi permeable membrane. Osmosis Which container has more water in it? http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf Osmosis- diffusion of water across a membrane Remember: Water always flows via osmosis from HIGH water concentration to LOW water concentration This cell would shrink! 22% Salt 5% Salt H2O H2O Osmosis- diffusion of water across a membrane -Water always flows via osmosis from HIGH water concentration to LOW water concentration -This cell bursts! 22% Salt 45% Salt H2O H2 O Isotonic Solution Water and dissolved substances diffuse into and out of the cell at the same rate. Plant Cell Blood Cell 11,397x HypOtonic Solution Solute concentration is higher inside the cell. Water diffuses into the cell, cell swells/bursts Plant Cell Blood Cell 13,000x Hypertonic Solution Solute concentration is higher outside the cell. Water diffuses out of the cell, cell shrivels Plant Cell Blood Cell 13,000x 3 Types of Solutions Cell in ________ Solution Cell in ________ Solution H2 O H2 O H2 O H2 O Cell in ________ Solution H2 O H2 O For each solution, determine if the solute concentration of the solution is high, the same, or low as compared the cell. Real life osmosis situations A salt water fish is put into a freshwater aquarium. What type of solution is the freshwater? What is going to happen to the cells of the fish? Real life osmosis examples Your garden is infested with slugs so you go around pouring salt on them What type of solution is this salt? What is going to happen to the cells of the slug? (don’t do this to the poor slugs ) Transport of Large Molecules Usually Transported by Vesicles EndocytosisInto the cell Exocytosis- Exiting the cell What kind of molecules do you think are usually found in the Vesicle? Do Now!! Please take out your homework!! Some important vocab… Plasmolysis: State where plant cells shrink in hypertonic environment (animal cells= “crenation”) Plant Cell Blood Cell Some important vocab… Cytolysis: State where cells burst in hypotonic environment Turgid: State where plant cells swell in hypotonic solution (animal cells=Lyse) Plant Cell Blood Cell Some important vocab… Flaccid: State where a plant cell is placed in isotonic solution Plant Cell
