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CELLS

CELLS. Chapter 3. A. The Early Years Robert Hooke (1660) 1st person to see the outlines of cells Antonie van Leeuwenhoek (1673) developed high magnification lenses 1st record of microorganisms Matthias Schleiden & Theodore Schwann (1839) & Rudolph Virchow (1855)

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CELLS

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  1. CELLS Chapter 3

  2. A. The Early Years • Robert Hooke (1660) • 1st person to see the outlines of cells • Antonie van Leeuwenhoek (1673) • developed high magnification lenses • 1st record of microorganisms • Matthias Schleiden & Theodore Schwann (1839) & Rudolph Virchow (1855) • contributed to the celltheory

  3. Cell Theory 1. All living things are composed of cells. [Schleiden & Schwann] 2. All cells come from preexisting cells. [Virchow]

  4. B. Cell Size • Most are 1-100m in diameter • Smallest? • Largest? • Why can’t cells grow to be as large as a car? - surface area/volume ratio - as cell grows, its volume increases more rapidly than its surfacearea

  5. C. Types of Cells 3 basic types: • Bacterial • Archaean Prokaryotic • Eukaryotic

  6. 1. Bacterial cells • 1-10 m in diameter • NO membrane-bound organelles • 1 circular DNA molecule located in nucleoid region • plasma membrane, cytoplasm & ribosomes • most have a cell wall(peptidoglycan) • may have a polysaccharide capsule Ex. bacteria & cyanobacteria

  7. 2. Archaean cells • 1-10 m in diameter • NO membrane-bound organelles • cell walls lack peptidoglycan • have characteristics of both bacteria & eukaryotic cells Ex. methanogens, extreme halophiles & extreme thermophiles

  8. 3. Eukaryotic cells • 10-100 m in diameter • nucleus & other membrane-bound organelles • 2 or more linear DNA molecules located in nucleus • plasma membrane, cytoplasm & ribosomes • some have a cell wall (cellulose or chitin) Ex. plants, animals, fungi, protista

  9. Generalized Generalized Animal Cell Plant Cell

  10. D. Organellesof Eukaryotic Cells Organelles compartmentalize a cell’s activities. 1. Nucleus • surrounded by a double membrane (nuclear envelope), perforated with nuclear pores • contains DNA & nucleolus (stores RNA nucleotides) • functions to separate DNA from rest of cell

  11. Nucleolus

  12. 2. Endoplasmic reticulum (ER) • interconnected network of membranes extending from nucleus to plasma membrane

  13. Rough ER - studded with ribosomes • site of protein synthesis (most will be exported out of the cell) Free ribosomes in the cytoplasm synthesize proteins that remain in cell. Smooth ER -lacks ribosomes • site of lipid synthesis • contains enzymes that detoxify drugs & poisons

  14. 3. Golgi apparatus • stacks of membrane-enclosed sacs

  15. Functions: • links simple carbohydrates together to form starch • links simple carbohydrates to proteins (glycoprotein) or lipids (glycolipid) • completes folding of proteins • temporarily stores secretions (milk)

  16. Organelle interaction in a mammary gland cell.

  17. 4. Mitochondria • double-membrane • outer is smooth • inner is highly folded (cristae) • #/cell varies • contain DNA • inherited from female parent • site of cellular respiration (production of ATP)

  18. 5. Chloroplasts • possess 3 membranes • outer/inner membranes surround stroma • 3rd membrane system folded into flattened sacs (thylakoids) • #/cell varies • contain DNA • found in plants & protists • function in photosynthesis

  19. 6. Lysosomes (suicide sacs) • vesicles containing > 40 types of digestive enzymes • function to recycle damaged organelles, break down cellular byproducts & destroy invading microbes

  20. 7. Peroxisomes • vesicles containing several types of enzymes (produced in cytoplasm) • found in all eukaryotic cells • function to help cell use oxygen & metabolize potentially toxic compounds

  21. E. The Endosymbiont Theory Proposes that chloroplasts and mitochondria evolved from once free-living bacteria engulfed by larger archaea. Based on fact that mitochondria & chloroplasts resemble certain bacteria (size, shape, membrane structure & method of making proteins).

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