CELLS

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CELLS

• Chapter 3

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• 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 cell theory

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• Cell Theory
• 1. All living things are composed of cells.
  Schleiden Schwann
• 2. All cells come from preexisting cells.
  Virchow

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• B. Cell Size
• Most are 1-100?m in diameter
• Smallest?
• Largest?
• Why cant cells grow to be as large as a car?
• - surface area/volume ratio
• - as cell grows, its volume increases more
  rapidly than its surface area

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• C. Types of Cells
• 3 basic types
• Bacterial
• Archaean

Prokaryotic

• Eukaryotic

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• 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

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• 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
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• 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

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• Generalized Generalized
• Animal Cell Plant Cell

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• D. Organelles of Eukaryotic Cells
• Organelles compartmentalize a cells 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

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

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• 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

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

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• 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)

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• Organelle interaction in a mammary gland cell.

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• 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)

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• 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

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• 6. Lysosomes (suicide sacs)
• vesicles containing gt 40 types of digestive
  enzymes

• function to recycle damaged organelles, break
  down cellular byproducts destroy invading
  microbes

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• 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

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• 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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