1 / 76

FOOD FOR THOUGHT

Learn about the purpose of microscopes, magnification, and resolving power. Discover how light and electron microscopes work, and the different types of electron microscopes. Dive into the history of cell discovery and the cell theory. Explore cell isolation techniques and the major categories of cells. Take a tour of a eukaryotic cell, including the cytoplasm, nucleus, ribosomes, endomembrane system, and more.

kbirkholz
Download Presentation

FOOD FOR THOUGHT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 endo-membrane 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

More Related