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Cellular Classification & Organelles: A Look at the Endomembrane System

Cellular Classification & Organelles: A Look at the Endomembrane System. Biology 111 Holyoke Walsh. Cells. http://www.youtube.com/watch?v=IcevP5tkWH0&feature=related. COMPARING CELLS. The size & shape of a cell relates to its function . . Cells . All cells are classified as either

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Cellular Classification & Organelles: A Look at the Endomembrane System

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  1. Cellular Classification & Organelles: A Look at the Endomembrane System Biology 111 Holyoke Walsh

  2. Cells • http://www.youtube.com/watch?v=IcevP5tkWH0&feature=related

  3. COMPARING CELLS • The size & shape of a cell relates to its function.

  4. Cells • All cells are classified as either • Prokaryote • Eukaryote

  5. Prokaryote Cells • no membrane bound nucleus, chromosomes grouped together in an area called the "nucleoid" • no membrane bound organelles • smaller than eukaryotes

  6. have cell wall and cell membrane, some have a capsule on the outside • ribosomes make protein • consist of bacteria and archaebacteria • Appendages include:  fimbriae/pili, flagella *pili are usually longer and fewer than fimbriae, both function for attachment and recognition of host cells (pili has a function for sexual reproduction)

  7. Figure 4.4a

  8. E. coli

  9. Eukaryotes • has a membrane bound nucleus • has membrane bound organelles in cytoplasm • Organelles perform specific functions • much larger than prokaryotes Organisms within the animal, plant, fungi and protista kingdoms are all eukaryotes

  10. We will be spending a lot of time on organelles and their functions.

  11. Figure 4.6b

  12. Figure 4.7b

  13. Prokaryote vs Eukaryote Cells Endosymbiosis theory: All organelles seem to share many properties with bacteria. Lynn Margulis proposed endosymbiont hypothesis: that organelles derived from ancient colonization of large bacteria (became the eukaryotic cell) by smaller bacteria (became the mitochondria, chloroplast, etc.) Symbiosis = "living together". *Mitochondria & Chloroplasts have their own DNA Animation at Microbiological Concepts

  14. Commonalities…of all cells!! • Plasma Membrane • Cytoplasm • Chromosomes (DNA) • Ribosomes

  15. Key Differences? • The location of their DNA; membrane bound organelles • Prokaryote = nucleoid region • Eukaryote = nucleus

  16. Prokaryote vs. Eukaryote

  17. Prokaryote or Eukaryote??

  18. Prokaryote or Eukaryote??

  19. Prokaryote or Eukaryote??

  20. Eukaryotes • In addition to the plasma membrane at its outer surface, a eukaryotic cell has extensive & elaborately arranged internal membranes, which divide the cell into compartments. • These provide different local environments that facilitate specific metabolic functions, so incompatible processes can go on simultaneously in a single cell • The plasma and organelle membranes participate directly in the cell’s metabolism b/c many enzymes are built right into the membranes themselves.

  21. Cell Membranes..in general • Phospholipid bilayer • Embedded proteins • Each type of membrane has a unique composition of lipids and proteins suited to that membrane’s specific function Ex: enzymes embedded in the mitochondrial membrane function in cellular respiration…which creates the ATP energy our cells need to function!

  22. Cell Membrane

  23. Pg 64

  24. Eukaryotes…genetic info… • Two cellular components involved with the genetic control of the cell are the NUCLEUS & the RIBOSOMES

  25. NUCLEUS

  26. The Nucleus 

  27. The Nucleus • Nuclear envelope contains nuclear pores for some things to enter and exit (nucleoplasm within) • Chromatin is DNA and proteins, when the cell begins to divide, chromatin condenses and forms chromosomes • DNA remains in the nucleus, it sends instructions to the cytoplasm via messenger RNA • RNA directs the synthesis of proteins on ribosomes in the cytoplasm • Nucleolus assembles ribosomes within the nucleus, ribosomes contain the "tools" to construct proteins

  28. Chromosomes – made of DNA/Protein! • DNA: Polymer of millions of nucleotides Nucleotide = Deoxyribose Sugar (pentose) +Phosphate + Nitrogen Base

  29. One Strand of DNA The backbone of the molecule is alternating phosphates and deoxyribose sugar The teeth are nitrogenousbases. phosphate deoxyribose bases 29

  30. DNA Double Helix A T C G T A G C G C Bases: Cytosine C Thymine T Adenine A Guanine G http://www.youtube.com/watch?v=qy8dk5iS1f0

  31. Ribosomes • Made of some RNA (genetic info) and Protein • each is composed of two subunits, one large and one small • Non-membranous organelles • Vary in size (smaller in prokaryotes) • Main function is to carry out protein synthesis.

  32. Ribosomes cont… • Cells that have high rates of protein synthesis have particularly high rates of ribosomes • Located in the cytoplasm/ER (structurally identical) • Free ribosomes – function within the cytosol (ie. enzymes that catalyze reactions) • Attached ribosomes – generally destined for insertion into organelles membranes or for export (cells that secrete enzymes) • Why does the human pancreas have millions of ribosomes?

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