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Cell Structure and Function

Learn how microscopes, including light and electron microscopes, allow us to create detailed images of cells and their components that are otherwise too small to see with the naked eye.

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Cell Structure and Function

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  1. Cell Structure and Function Chapter 4

  2. Microscopes • Create detailed images of something that is otherwise too small to see • Light microscopes • Simple or compound • Electron microscopes • Transmission EM or Scanning EM

  3. MICROSCOPE CHART

  4. In-text, p. 54

  5. Limitations of Light Microscopy • Wavelengths of light are 400-750 nm • If a structure is less than one-half of a wavelength long, it will not be visible • IF TOO SMALL  LIGHT CAN’T PASS THROUGH IT  can’t see it

  6. which 2 ways does the LM turn its image? If you see this on slide, r upside down flipped r r Then you’ll see this in the microscope

  7. What are the 3 things that LM do to images? • Flip • Invert • magnify

  8. Estimate the actual size of this cell. ratio: 100mm x Diameter of power Width of “thing” Width of circle = 45mm 45 x = 100x 100 5 x 2.25mm = 2,250micrometers

  9. Electron Microscopy • Uses streams of accelerated electrons rather than light • Electrons are focused by magnets rather than glasslenses

  10. ~45x SEM

  11. TEM Images Au atoms The First Atom Image ! -of a 2.5 nm small gold cluster in 1982

  12. Important events in the discovery of cells: • Robert Hooke: (1665) Examined shredded bark of oak trees (cork): observed boxlike units which were empty inside. He called these units “cells”. He described them as being “walls of enclosed space, such as a box. He believed that only plants were made of cells b) Anton van Leeuwenhoek: (1673) microscope maker, studied organisms living in pondwater, saw firstunicellular organisms c) Henri Dutrochet : (1824) was the first to suggest that all living things are composed of cells <<LINK>>

  13. Anton von Leeuwenhoek

  14. d)Robert Brown: (1831) identified a structure within the fluid of a plant cell – THE NUCLEUS. He didn’t identify its function I discovered the NUCLEUS.. Nah, I’m just messin’ I FEEL GOOD .. OW!

  15. e) Matthias Schleiden: (1838) German botonist that observed plant cells. He suggested that all plant tissue was made up of cells and expanded on Brown’s work by suggesting the nucleus plays a role in cell reproduction II. Developing Cell Theory

  16. f) Theodor Schwann: (1839) German zoologist who observed animal cells and found that animal tissue resembled plant tissue. He concluded that the cell was the basic unit of animal. g) Rudolf Virchow: (1855) All plant and animal cells are produced from the division of other cells

  17. why did it take so long to learn about cells? • Scientists had to build off each other’s ideas • Had to wait for stronger technology • Culture/religion inhibiting progress

  18. III. Cell Theory a) All organisms are composed of one or more cells b) The cell is the basic unit of structure and function in all living things (anything smaller than a cell is not alive) c) Cells arise by division from pre- existing cells

  19. IV. Cell Size • Range from largest cell (ostrich egg) to bacterial cells (need a microscope) • Limited to being … small

  20. Why Are Cells So Small? • Surface-to- volume ratio • The bigger a cell is, the less surface area there is per unit volume • Above a certain size, material cannot be moved in or out of cell fast enough

  21. red went the furthest in

  22. Cells need to be SMALL so they could all FIT in/on the organism! • HOW MANY CELLS ARE THERE IN A HUMAN BODY???? 10 QUADRILLION! There’s more bacteria than your body cells!..

  23. IV. Cell Shape • Shape has to do with function • Ex. Skin, nerve, white blood cells Change shape To engulf

  24. V. Other Features of Cells • Highly complex internal structure made up of organelles • Have genetic information • (DNA  RNA  make proteins that make up YOU) • Can get and use energy • Photosynthesis • Cellular respiration

  25. Can metabolize – make up and break down of molecules in reactions • Can move (even organelles) / respond to stimuli (light, touch..etc)

  26. f. All cells contain the following 3 structures: 1. Plasma Membrane – separates the cell from the external environment 2. Cytoplasm – fluid filled cell interior 3. Nuclear area – genetic information stored as DNA

  27. VI. 2 Types of Cells: a. Prokaryotes (prokaryotic) cells: 1. Pro = before karyon = nucleus 2. Size relative to eukaryotes? small (5 – 10 um) 3. lack membrane-bound organelles (no nucleus, vacuoles, ER…) 4. NO nucleus, NUCLEIOD instead 5. most primitive type of cell 6. Includes what 2 Domains? Bacteria and Archeobacteria

  28. Prokaryotic Cells • Domains: Archea and Bacteria • DNA is NOT enclosed in nucleus • Generally the smallest, simplest cells • No organelles

  29. Prokaryotic Structure nucleoid cytoplasm with ribosomes DNA flagellum capsule cell wall plasma membrane

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