1.2 Cell Structure

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  • Cell Structure
    • Endoplasmic Reticulum (ER)
      • single membrane layer
      • a system of highly branched and rejoin network of cisternae extending from nucleus to cyto
        • cisterna(e)
          • membrane-bound sacs
      • Structure and Function
        • Smooth ER (SER)
          • tubular cisternae
          • site of lipid and steroid synthesis
            • ex: reproductive hormones cholesterol
        • Rough ER (RER)
          • flattered cisternae
          • heavily coated with ribosomes
            • 1.protein synthesis
              • 2. transport proteins to SER
          • 1.protein synthesis
            • 2. transport proteins to SER
        • intracellular transport system
    • RIbosomes
      • Structure and Function
        • consist of small and large subunits
          • made of protein and ribosomal (r)RNA
        • protein synthesis
          • free rib- used in cyto
          • on RER -used out of cyto
      • d= 20nm
      • found in cyto (free ribosomes), RER, mitochondria and chloroplast
        • 70s (smaller) in mito and chlorop
        • 80s in cyto and RER
      • non-membrane bound
    • Golgi Apparatus
      • Structures and Function
        • stacks of flattened disc like cisterna(e)
          • outer forming face
            • convex
            • transport vessicles from ER form new cisternae
            • collect and modify molecules from ER
              • inner maturing face
                • concaved
                • cisternae moves from outer forming inner face
              • ex: glycosylation
                • DEF: addition of short carbo chain
                • to protein = glycoproteins
                • to lipids = glycolipids
          • inner maturing face
            • concaved
            • cisternae moves from outer forming inner face
        • golgi / secretory vessicles
          • transport / distribute products
        • makes lysosomes
      • single membrane layer
    • Lysosomes
      • 0.5microm
      • fluid filled sac (vesicle) enclosed by single membrane layer
      • formed by pinching off from golgi body
      • Structure and Function
      • contains >/= 40 types of hydrolytic enzymes
        • enzymes work best in acidic env
    • Nucleus
      • 10microm (biggest cell organelle)
      • Structure and Functions
        • nucleolus
          • produces ribosomes and rRNA
        • chromatin
          • (a string of DNA wrapped around ball-like histone proteins)
            • euchromatin
              • uncoiled chromatin
              • contains genes that can be expressed
            • heterochromatin
              • densely coiled and condensed chromatin
        • nucleoplasm (nuclear sap)
        • inner + outer membrane
          • forms nuclear envelope
          • double membrane layer
            • Nucleus
              • 10microm (biggest cell organelle)
              • Structure and Functions
                • nucleolus
                  • produces ribosomes and rRNA
                • chromatin
                  • (a string of DNA wrapped around ball-like histone proteins)
                    • euchromatin
                      • uncoiled chromatin
                      • contains genes that can be expressed
                    • heterochromatin
                      • densely coiled and condensed chromatin
                • nucleoplasm (nuclear sap)
                • inner + outer membrane
                  • forms nuclear envelope
                  • double membrane layer
                  • nuclear pore
                    • controls entry and exit of substances form the nucleus
                  • control all cellular activities
                    • ex: heredity metabolism reproduction
          • nuclear pore
            • controls entry and exit of substances form the nucleus
          • control all cellular activities
            • ex: heredity metabolism reproduction

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