BMSC 220 2 Structure and diversity of cells

  1. Cell Theory (3 major points/ people)
    • Theodor Schwann, Jakob Schleiden
    • 1.  All organisms are composed of one or more cells
    • 2.The cell is the structural and functional unit of life

    • Rudolph Virchow
    • 3.  Cells can arise only by division from a preexisting cell
  2. 4 macromolecules
    • Nucleic Acids    
    • Proteins    
    • Lipids    
    • Carbohydrates
  3. Requirements for formation of first cell
    • •Organic molecules (carbon-based)
    • •Molecules for catalysis of chemical reactions and self-replication
    • •A barrier between the internal cell environment and the external environment
  4. Requirement 1:  Organic molecules
    •Spontaneous synthesis of organic molecules probably provided the basic materials from which the first living organisms arose.
  5. Requirement 2:  Molecules for catalysis of chemical reactions and self-replication
    RNA probably first genetic material is only molecule able to both catalyze chemical reactions (ribozyme), and self replicate (through nucleotide base pairing)
  6. Requirement3:  a barrier between the internal cell environment and the external environment
    •Phospholipids are the basic components of all present-day biological membranes, including the plasma membranes of both prokaryotic and eukaryotic cells.
  7. 3 types of Bacteria
    • •Archaebacteria
    • •Eubacteria
    • •Cyanobacteria
  8. Archaebacteria
    were prevalent in primitive Earth and often live in extreme environments
  9. Eubacteria
    a large group of organisms (including common forms of bacteria) that live in a wide range of environments, including soil, water, and other organisms (e.g., human pathogens).
  10. Cyanobacteria
    the largest and most complex prokaryote, synthesizes its energy from photosynthesis.
  11. Nucleoid
    • a single circular molecule
    • Where the DNA of Bacteria is found
  12. Mitochondria:
    in all eukaryotic cells, are the sites of oxidative metabolism
  13. Chloroplasts:
    found only in cells of plants and green algae, are the sites of photosynthesis
  14. Lysosome
    provide specialized metabolic compartment for digestion of macromolecule
  15. Peroxisomes
    perform various oxidative reactions
  16. Vacuoles:
    • variety of functions in plant cells
    • -digestion of macromolecules and storage of waste products and nutrients.
  17. Endoplasmic reticulum:
    • -an extensive network of intracellular membranes
    • - functions in the processing and transport of proteins, and in the synthesis of lipids.
  18. Golgi apparatus:
    • -sorts and transports proteins destined for secretion and serves as a site of lipid synthesis  -(in plant cells)
    • - synthesis of some of the polysaccharides that compose the cell wall
  19. cytoskeleton
    • -provides the structural framework of the cell -responsible for the movements of entire cells, and intracellular transport / positioning of organelles and other structures
    • -Composed of actin filaments, intermediate filaments, microtubules
  20. Yeasts
    the simplest eukaryotes; more complex than bacteria, smaller and simpler than cells ofanimals or plants.
  21. Saccharomyces cerevisiae
    • -commonly studied yeast 
    • - unicellular, but communicate between cells
  22. •Plant cells are organized into three main tissue systems:
    • 1) ground tissue
    • 2) dermal tissue
    • 3) vascular tissue.
  23. Humans have over ___ distinct tissue types, organized into five main tissue systems:

    • Epithelial
    • Connective
    • Blood
    • Nervous
    • Muscle
  24. Epithelial cells-
    • form sheets that cover the surface of the body and line the internal organs. 
    • -specialized for protection, secretion, absorption
  25. Connective tissues
    • bone, cartilage, and adipose tissue
    • Fibroblasts .
  26. Fibroblasts
    are a cell type that fill the spaces between organs and tissues in the body.
  27. Blood
    • -contains red blood cells (erythrocytes) and white blood cells
    • -red blood cells don’t have nucleus
  28. Nervous tissue
    -composed of supporting cells and nerve cells, or neurons, which are highly specialized to transmit signals throughout the body.
  29. Muscle
    3 types
    • -responsible for the production of force and movement
    • Skeletal, smooth muscle Cardiac muscle
  30. pros and cons of the model organisms used in the study of cells:
    Bacteria/ E. Coli
    • -relative simplicity and ease of propagation.
    • •Divide every 20 min. under optimal conditions to produce clonal colonies.
    • •Small genome  4.6 million bp,  4300 genes.
    • •Ability to carry out biosynthetic reactions in simple defined media -  useful in elucidating biochemical/genetic pathways.
    • •Useful for DNA/gene cloning and   manipulation
  31. pros and cons of the model organisms used in the study of cells:
    • -more manageable experimentally than the genomes of complex eukaryotes such as humans
    • •Readily grown in the lab - divides every 2 hrs
    • •studied by many of the same molecular/genetic approaches as for E. coli
    • .•Yeast mutants -  used to study fundamental processes in eukaryotes, - DNA replication, transcription, RNA processing, protein sorting, regulation of cell division.
  32. pros and cons of the model organisms used in the study of cells:
    C. elegans (nematode)
    • -is a relatively simple multicellular organism (959 somatic cells)
    • •entire cell lineage known
    • •easily grown and subjected to genetic manipulations in the laboratory
  33. pros and cons of the model organisms used in the study of cells:
    Drosophila melanogaster (fruit fly)
    • -easily maintained and bred in the laboratory
    • -Studies of development, pattern formation
  34. pros and cons of the model organisms used in the study of cells:
    Xenopus laevis -
    • -early vertebrate development eggs develop outside mother
    • -all stages of development from egg to tadpole can be  studied in the laboratory.
  35. pros and cons of the model organisms used in the study of cells:
    easy to maintain, reproduce rapidly, amenable to genetic manipulation, and have transparent embryos.
  36. pros and cons of the model organisms used in the study of cells:
    • -easy to keep in lab, complete genome sequence
    • - Often used as transgenic animals to study known human genetic disease
  37. Microscopy:  light (bright-field),
    2 pioneers
    • •Robert Hooke invented the first simple light microscope in 1665.
    • •In the 1670s, Antony van Leeuwenhoek microscope magnified objects up to 300 times-sperm, blood, bacteria.
  38. Microscopy:  light (bright-field),
    max magnification
    • •The light microscope remains a basic tool of cell biology
    • -can to magnify objects up to 1000X.
  39. Microscopy:  light (bright-field),
    2 lenses
    Objective lens: adjustable lense just above specimen

    condenser lense: focus' light source
  40. Resolution
    -ability to distinguish objects
  41. phase contrast/ differential interference-contrast,
    • •optical systems that convert variations in density or thickness
    • -contrast that can be seen in the final image without staining.
    • •Allows visualization of live cells
  42. fluorescence microscopy
    • -widely used and very sensitive method to study intracellular distribution of molecules.
    • -Fluorescent markers, dyes and proteins (eg. green fluorescent protein(GFP))  used to visualize proteins/structures in living cells
  43. green fluorescent proteins (GFP)
    • -allowed visualization (without staining/killing) of specific molecules and structures in living cells
    • -first isolated in jelly fish
  44. •The electron microscope- 
    3 pioneers
    • Albert Claude, Keith Porter, and George Palade -1940 and 50s.
    • Achieve much greater resolution - wavelength of electrons shorter than visible light
  45. scanning Electron microscopy,
    • •electron beam reflects off sample surface- coated with metal
    • -provides 3-dimensional surface image
  46. transmission electron microscopy-
    passes a beam of electrons through a specimen to form an image on a fluorescent screen.
  47. Biochemical: subcellular fractionation:
    •Differential centrifugation:
    separates and isolates organelles (size and density) for use in biochemical studies.
  48. •ultracentrifuge
    -can rotate samples at very high speeds (over 100,000 rpm) to produce forces up to 500,000 times greater than gravity.

    -The force of an ultracentrifuge causes cell components to move toward the bottom of the centrifuge tube and form a pellet at a rate that depends on their size and density
  49. Cell culture: primary cultures,
    are the first cell cultures established from a tissue (limited number of divisions before death).
  50. immortal cell cultures
    - embryonic stem cells or cells derived from tumors that may proliferate indefinitely in culture.
  51. •Media used for animal cell cultures contain:
    serum, salts, glucose, amino acids and vitamins.
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BMSC 220 2 Structure and diversity of cells
BMSC 220 2 Structure and diversity of cells