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FOOD FOR THOUGHT

FOOD FOR THOUGHT. Figure 4.3. Microscopes as a Window on the World of Cells. Microscopy: purpose to magnify images too small to see. Magnification Is an increase in the specimen’s apparent size . Resolving power

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FOOD FOR THOUGHT

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  1. FOOD FOR THOUGHT

  2. Figure 4.3

  3. Microscopes as a Window on the World of Cells • Microscopy: purpose to magnify images too small to see • Magnification • Is an increasein the specimen’s apparent size. • Resolving power • Is the ability of an optical instrument to show two objects as being separate. Euglena

  4. The light microscope is used by many scientists. • Light passes through the specimen. • Lenses enlarge, or magnify, the image.

  5. The electron microscope (EM) uses a beam of electrons. • It has a higher resolving power than the light microscope. • The electron microscope can magnify up to 100,000X. • Such power reveals the diverse parts within a cell.

  6. The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell. A beam of electrons transmitted through the slice- produces a cross section

  7. The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell. Beam of electrons reflected off surface- 3-D image

  8. Cells were first discovered in 1665 by Robert Hooke. • The accumulation of scientific evidence led to the cell theory. • All living things are composed of cells. • All cells are formed from previously existing cells. • Cells are smallest unit of life

  9. Isolating Techniques of cool stuff inside a cell • - Cell fractionation • - Split everything apart • - Centrifuge based on mass

  10. The Two Major Categories of Cells • The countless cells on earth fall into two categories: • Prokaryotic cells • Eukaryotic cells • Prokaryotic and eukaryotic cells differ in several respects.

  11. Figure 4.4

  12. Prokaryotic cells • Are smaller than eukaryotic cells. • Lack internal structures surrounded by membranes. • Lack a nucleus. • Examples: Bacteria and Archae

  13. Figure 4.5

  14. Eukaryotic cells • Are larger than prokaryotic cells. • Have internal structures surrounded by membranes. • DNA contained within a nucleus. • Examples: Protists, Fungi, Plant and Animal

  15. A Panoramic View of Eukaryotic Cells • An idealized animal cell

  16. An idealized plant cell Cytoplasmic Streaming

  17. The Microscopic World of Cells • Organisms are either: • Single-celled, such as most bacteria and protists • Multicelled, such as plants, animals, and most fungi • For the most part cells are small • Exception: bird eggs, neurons, some algae and bacteria

  18. Tour of a Eukaryotic Cell • - Cytoplasm • - Nucleus • - Ribosomes • - Endomembrane System • - Nuclear Envelope • - ER • - Golgi Apparatus • - Lysosomes • - Vacuoles • - Plasma (Cell) Membrane • - Mitochondria • - Chloroplasts • - Cytoskeleton

  19. Cytoplasm • All cells have cytoplasm that includes everything inside the cell like organelles. AKA cytosol it is a jelly-like substance.

  20. The Nucleus • Nucleus Definition: • The nucleus is the manager of the cell. • DNA that holds the genes in the nucleus store information necessary to produce proteins. • It contains chromatin and chromosomes. • DNA + Protein ; condensed chromatin • It contains a nucleolus. • Synthesizes Ribosomes

  21. Structure and Function of the Nucleus • The nuclear envelope (a double membrane) borders the nucleus and contain pores. Nuclear lamina on the inside layer of the envelope helps maintain the shape of the nucleus

  22. Ribosomes • Ribosomes (folded strands of ribosomal RNA) are responsible for protein synthesis. • Free ribosomes usually make proteins that will function/stay in the cytosol. • Bound ribosomes (attached to the Endoplasmic Reticulum) usually make proteins that are exported or included in the cell's membranes. • Cool fact: free ribosomes and bound ribosomes are interchangeable and the cell can change their numbers according to metabolic needs.

  23. DNA controls the cell by transferring its coded information into RNA. • The information in the RNA is used to make proteins. Figure 4.9

  24. The Endomembrane System: Manufacturing and Distributing Cellular Products • Includes many of the membranous organelles in the cell belong to the endomembrane system.

  25. The Endoplasmic Reticulum • The endoplasmic reticulum (ER) • System of membranes that produce an enormous variety of molecules. • Is composed of smooth and rough ER.

  26. Smooth ER – lacks surface ribosomes • Synthesizes: produces phospholipids, steroids and hormones; metabolizes carbs (in the liver) • Participates: in hydrolysis of glycogen (animal cells) • Detoxifies: by chemically modifying drugs and pesticides • Stores and modifies: proteins made by ribosomes and RER • .

  27. Rough ER • The “roughness” of the rough ER is due to ribosomes that stud the outside of the ER membrane. • Formation: • Synthesize: Proteins (made by ribosomes) enter RER • Proteins are altered (folded or have other molecules attached) • Carbohydrates are attached to change function and act as a “name tag” so the protein “knows” where to go (usually to the membrane) • Transports: vesicles containing proteins

  28. Figure 4.11

  29. The Golgi Apparatus • The Golgi apparatus • Works in partnership with the ER (modifies and transports proteins). • Refines, stores, and distributes the chemical products of cells.

  30. Figure 4.12

  31. Parts of the Golgi • Three distinct parts (top, middle and bottom): • Bottom: cis region is close to nucleus/RER • Receiving end • Middle: cisternae is in between • transport • Top: trans region is close to surface of cell • Exit end

  32. Lysosomes • A lysosome is a membrane-enclosed sac. • It contains digestive (hydrolytic) enzymes. • The enzymes break down macromolecules, digest food, and break down damaged organelles. • - Examples: • - Autophagy - recycling of cell parts • - Phagocytosis by amoeba and macrophages • - Development - Digestion of tadpole tail, webbing between fingers • - Tay-Sach's Disease • - lipid digestion enzyme is missing from lysosomes and lipids accumulate in the brain

  33. Lysosomes have several types of digestive functions. • They fuse with food vacuoles to digest the food. Lysosome Formation

  34. Vacuoles • Vacuoles are membranous sacs. There are three types: • Food vacuoles- contain food/water for cell • contractile vacuoles of protists: used for osmoregulation (pump water out of cell thru pore) Paramecium Vacuole

  35. central vacuoles of plants: • act as a reservoir of nutrients: ~toxic by-products ~waste products (with storage makes plant taste bad and protects from predators!) ~nutrients/proteins/carbohydrates • generate turgor • aids in growth

  36. Figure 4.14

  37. Peroxisomes • These organelles collect toxic peroxides which are byproducts of chemical reactions • Ex: hydrogen peroxide H2O2

  38. A review of the endomembrane system Figure 4.15

  39. HOMEWORK DUE FRIDAY • Create a story about how 10 cellular organelles worked together to complete a goal! Must include functions.

  40. Chloroplasts and Mitochondria: Energy Conversion • Cells require a constant energy supply to do all the work of life.

  41. Mitochondria • Mitochondria are the sites of cellular respiration, which involves the production of ATP from food molecules. • Found in most eukaryotes

  42. Chloroplasts • Chloroplasts are the sites of photosynthesis, the conversion of light energy to chemical energy.

  43. Mitochondria and chloroplasts share another feature unique among eukaryotic organelles. • They contain their own DNA. • The existence of separate “mini-genomes” is believed to be evidence that • Mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past.

  44. Other features of Chloroplasts • Plastids- an organelle only in plant cells and some protists. They can differentiate into… • Amyloplast- aka leukoplast (white/colorless) plastid that converts glucose to starch. Found in potatoes! • Chromoplast-contain red, orange and/or yellow pigments. Aid in pollination and seed dispersal • Chloroplast- green pigment chlorophyll (light energy converted to chemical energy)

  45. The Cytoskeleton:Cell Shape and Movement • The cytoskeleton is an infrastructure of the cell consisting of a network of fibers. • Functions of the cytoskeleton • provide mechanical support for the cell and maintain its shape. • Aids in cellular movement/change shape • Positions organelles within the cell • Act as tracks for other objects to move on • Anchor the cell

  46. Figure 4.18a

  47. Microtubules • Make the internal skeleton for cells and aid in protein movement thru cell • Push/pull chromosomes to daughter cells • Make up cilia and flagella

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