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Are All Cells Alike?

Section 7-1. Are All Cells Alike?. All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells. 1. What are the advantages of a one-celled organism? 2. What are the advantages of an organism that is made up of many cells?.

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Are All Cells Alike?

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  1. Section 7-1 Are All Cells Alike? • All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells. • 1. What are the advantages of a one-celled organism? • 2. What are the advantages of an organism that is made up of many cells?

  2. Section Outline Section 7-1 • 7–1 Life Is Cellular A. The Discovery of the Cell 1. Microscopes 2. The Cell Theory B. Exploring the Cell C. Prokaryotes and Eukaryotes 1. Prokaryotes 2. Eukaryotes

  3. Section 7-1 Discovery of the Cell Robert Hooke – 1665 – named cell Leeuwenhoek – 1674 – observed living microorganisms Schleiden – 1838 – all plants made of cells Schwann – 1839 – all animals made of cells Virchow – 1855 - all cells come from cells

  4. Section 7-1 Exploring the Cell Microscopy - the history of cytology is tied to the development of the microscope. Light microscopes - pass light through the specimen - can magnify up to about 1200x - easy to prepare specimens and can look at living specimens.

  5. Section 7-1 2. Transmission Electron Microscope - send a beam of electrons through the specimen - focused with magnets - resolving power up to 100,000(+)x - specimens have to be prepared and can’t be alive

  6. Section 7-1 3. Scanning Electron Microscope - bounce electrons off the surface of the specimen - gives detailed three-dimensional images of the surface of the specimen

  7. Section 7-1 • Cell Theory • Cells are the basic structural and functional units of life • Under the conditions present on Earth today all cells come from other cells. • All living things are composed of cells

  8. Section 7-1 • Prokaryotes-cells that have genetic material that is not contained in the nucleus. Generally smaller and more simple than eukaryotes. • Bacteria are prokaryotes. • Eukaryotes-contains a nucleus in which their genetic material is separated from the rest of the cell. Plants, animals, fungi, and protists are Eukaryotes.

  9. Cell membrane Cytoplasm Cell membrane Cytoplasm Prokaryotic and Eukaryotic Cells Section 7-1 Prokaryotic Cell Nucleus Eukaryotic Cell Organelles

  10. Prokaryotes Eukaryotes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell membrane Contain DNA Venn Diagram Section 7-1

  11. Section 7-2 Division of Labor • A cell is made up of many parts with different functions that work together. Similarly, the parts of a computer work together to carry out different functions. • Working with a partner, answer the following questions. • 1. What are some of the different parts of a computer? What are the functions of these computer parts? • 2. How do the functions of these computer parts correspond to the functions of certain cell parts?

  12. Section Outline Section 7-2 • 7–2 Eukaryotic Cell Structure • A. Comparing the Cell to a Factory • B. Nucleus • C. Ribosomes • D. Endoplasmic Reticulum • E. Golgi Apparatus • F. Lysosomes • G. Vacuoles • H. Mitochondria and Chloroplasts 1. Mitochondria 2. Chloroplasts • 3. Organelle DNA • I. Cytoskeleton

  13. Section 7-2 • Nucleus • “control center” of the cell • Contains the chromosomes on which the genes are located • Fine threads called chromatin in nondividing cells • Condense into visible chromosomes during cell division • Nuclear membrane has two parallel membranes with nuclear pores penetrating them • Nuclear pores allow mRNA to leave the nucleus to go to the cytoplasm • Also contains the nucleolus where ribosomal subunits are produced

  14. Section 7-2 Ribosomes - sites of protein synthesis – where amino acids are joined - many are attached to Rough ER; others are free in the cytoplasm - composed of RNA and protein - attached ribosomes make proteins for export - free ribosomes make proteins for intracellular use

  15. Section 7-2 Endoplasmic Reticulum - membranous-walled canals and flat sacs that extend from the plasma membrane to the nucleus - important in the synthesis, modification, and movement of materials within the cell A. Rough Endoplasmic Reticulum - has ribosomes attached to its’ surface - ribosomes make proteins which move into the cisternae of the ER and are transported toward the Golgi apparatus

  16. Section 7-2 B. Smooth Endoplasmic Reticulum - lacks ribosomes - transports, synthesizes, and chemically modifies small molecules - synthesizes certain lipids and carbohydrates and creates membranes for use throughout the cell

  17. Section 7-2 Golgi Apparatus - series of flattened membranous sacs that modify protein products of the rough endoplasmic reticulum - final products are packaged in vesicles which can then be moved to the cell membrane for export - some of these vesicles remain in the cell as lysosomes - can also give rise to new membrane structures for the cell

  18. Section 7-2 Lysosomes - digestive system of the cell - membranous sacs which pinch off the Golgi apparatus - contain hydrolytic enzymes which digest particles or large molecules that enter them - also responsible for digesting unneeded or unhealthy cells and cell parts

  19. Section 7-2

  20. Section 7-2 Vacuoles - saclike structures used for storage within the cell - stores water, salts, proteins, and carbohydrates - discerning feature in many plant cells that is large and liquid filled makes possible for plants to support heavy structures such as leaves and flowers - in many cases the vacuole is controls the water content of the cell which maintains homeostasis

  21. Section 7-2 Mitochondria - “power plants” of cells - double membraned organelle with fluid between the membranes - lots of enzymes attached to both membranes - enzymes catalyze oxidation reactions of cellular respiration and capture the energy of sugars in the bonds of ATP - provide 95% of the cell’s energy - contain their own ribosomes and DNA and can replicate themselves

  22. Section 7-2 Chloroplasts - capture the energy of the sunlight and convert it into the chemical energy of sugar in a process called photosynthesis - double membraned organelle like mitochondria - also contain their own DNA - contain large stacks of membranes containing chlorophyll

  23. Section 7-2 Cytoskeleton Internal support framework made up of rigid, rodlike proteins that support the cell and allow movement and mechanisms that can move the cell or its parts Acts as both muscle and skeleton for cell Cell Fibers - form a three-dimensional support framework - support endoplasmic reticulum, mitochondria, and free ribosomes

  24. Section 7-2 1. Microfilaments – smallest fibers - cellular muscles that provide for movement 2. Intermediate filaments – form much of the support network of the cell 3. Microtubules – maintain cell shape and move things within the cell made up of proteins known as tublin 4. Tubulin is also used to make structures in animal cells known as the centrioles. These aid in organization during cell division

  25. Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion Figure 7-11 Cytoskeleton Section 7-2

  26. Smooth endoplasmic reticulum Vacuole Ribosome (free) Chloroplast Ribosome (attached) Cell Membrane Nuclear envelope Cell wall Nucleolus Golgi apparatus Nucleus Mitochondrion Rough endoplasmic reticulum Figure 7-5 Plant and Animal Cells Section 7-2 Plant Cell

  27. Ribosome (attached) Ribosome (free) Nucleolus Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus Figure 7-5 Plant and Animal Cells Section 7-2 Animal Cell

  28. Animal Cells Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts Centrioles Venn Diagram Section 7-2

  29. Section 7-3 In or Out? • How is a window screen similar to a cell membrane? Read on to find out. • 1. What are some things that can pass through a window screen? • 2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen? • 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?

  30. Section Outline Section 7-3 • 7–3 Cell Boundaries A. Cell Membrane B. Cell Walls C. Diffusion Through Cell Boundaries 1. Measuring Concentration 2. Diffusion D. Osmosis 1. How Osmosis Works 2. Osmotic Pressure E. Facilitated Diffusion F. Active Transport 1. Molecular Transport 2. Endocytosis and Exocytosis

  31. Section 7-3 • Cell Membrane • All of the membranes of the cell have similar structure. • Plasma Membrane • -Fluid Mosaic Model – developed by Singer and Nicolson • -Molecules are arranged in a sheet • -Molecules are held together by chemical attractions between them and their interactions with water. • -Primary structure is a double layer of phospholipid molecules Phosphate heads are hydrophilic; tails are hydrophobic

  32. Section 7-3 -Cholesterol molecules within the membrane help it function at body temperatures. -Because the hydrophobic tails make-up most of the membrane, water soluble materials can’t pass through the membrane. -Channel proteins which are embedded in the membrane help control movement of materials into and out of the cell -Glycoproteins have carbohydrates attached and serve as cell surface identifiers -Receptor proteins react to specific chemicals and cause changes within the cell. -Overall, the plasma membrane is selectively permeable. • Cell Membrane-cont.

  33. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Figure 7-12 The Structure of the Cell Membrane Section 7-3

  34. Section 7-3 -Provide support and protection for the cell. -Most are composed of fibers of carbohydrate and protein -Plant cell walls are mostly cellulose • Cell Walls

  35. Passive and Active Transport Section 7-3

  36. Section 7-3 Passive Transport Processes -Do not require energy expenditure by the cell -Second Law of Thermodynamics Diffusion - movement of particles from an area of high concentration to an area of low concentration down a concentration gradient. - continues until equilibrium is reached - membrane channels are pores through which specific ions or small water-soluble molecules can pass - gases also move by diffusion • Movement Through the Cell Boundaries

  37. Diffusion and Osmosis Video Section 7-3

  38. Section 7-3 Passive Transport Processes cont. Osmosis - diffusion of water through a selectively permeable membrane - water moves down it’s concentration gradient – this often means it is moving toward higher salt concentrations - Osmotic Pressure – water pressure that develops as a result of osmosis - healthy cells are normally in an environment where the net movement of water is 0.

  39. Section 7-3 Passive Transport Processes cont. Osmosis cont. - Tonicity – ability of a solution to move water in/out of a cell and change its shape a. Isotonic – osmotic pressure is = inside and outside b. Hypertonic – osmotic pressure is greater than within the cell – water moves out of cell causing crenation c. Hypotonic – osmotic pressure is less than within the cell – water moves into the cell causing lysis.

  40. Figure 7-15 Osmosis Section 7-3

  41. Figure Osmosis Section 7-3

  42. Osmosis Video Section 7-3

  43. Glucose molecules High Concentration Cell Membrane Protein channel Low Concentration Facilitated Diffusion Section 7-3 • Facilitated Diffusion - movement through carrier proteins along the concentration gradient - rate is dependent on concentration gradient and availability of carrier molecules

  44. Molecule to be carried Energy Molecule being carried Section 7-3 -cell uses metabolic energy to move materials 1. Molecular Transport - carrier-mediated process that moves substances against their concentration gradients - opposite of diffusion - substances are moved by pumps which use ATP to change shape and move their cargos - carrier proteins bind to cargo, change shape, and release the cargo • Active Transport

  45. Active Transport Section 7-3 Video 4

  46. Section 7-3 2. Endocytosis and Exocytosis - allow things to enter and leave a cell without actually passing through the plasma membrane. A. Endocytosis – plasma membrane traps some extracellular material and moves it to the interior in a vesicle. - Phagocytosis – large particles are engulfed within a vesicle that then fuses with lysosomes to digest particles - Pinocytosis – fluid and the substances dissolved in it enter the cell • Active Transport (cont.)

  47. Endocytosis and Exocytosis Section 7-3

  48. Section 7-4 From Simple to More Complex • Many multicellular organisms have structures called organs that have a specific function and work with other organs. Working together, these organs carry out the life processes of the entire organism.

  49. Section 7-4 • 1. Some activities cannot be performed by only one person, but need a team of people. What type of activity requires a team of people to work together in order to complete a task? • 2. What do you think are some characteristics of a successful team? • 3. How is a multicellular organism similar to a successful team?

  50. Section Outline Section 7-4 • 7–4 The Diversity of Cellular Life A. Unicellular Organisms B. Multicellular Organisms 1. Specialized Animal Cells 2. Specialized Plant Cells C. Levels of Organization 1. Tissues 2. Organs 3. Organ Systems

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