<aside> 💡 Cell Function- Plasma Membrane, Organelles & Cell Life Cycle

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1. Identify cellular organelles and describe their major structural features and functions

   1. Nucleus

      1. Largest membrane bound organelle
      2. Double membrane nuclear envelope, with nuclear pores; continuous with ER
      3. Houses genetic information
      4. Nucleolus site of ribosome production

   2. Mitochondria

      

      1. Site of ATP production form the aerobic respiration of organic molecules
      2. Highly folded inner membrane form mitochondrial cristae to increase surface are; contains enzymes for oxidative phosphorylation
      3. Small intermembrane space for building proton concentration
      4. Central fluid-filled cavity (mitochondrial matrix) contains enzymes for TCA cycle

   3. Endoplasmic Reticulum

      

      1. Network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane.

      2. Smooth devoid of ribosomes

      3. rough studded with ribosomes

      4. Synthesis: lipids, steroids (smooth) proteins for membrane, lysosome, secretion (rough)

      5. Transport (endomembrane system, moves through cristernal away from cytoplasm)

      6. Storage of newly synthesized molecules

      7. Detox: Cytochrome P450 enzymes break down drugs and alcohol

         

   4. Ribosome

      1. Site of polypeptide synthesis
      2. Large and small subunit made of rRNA

   5. Golgi apparatus

      

      1. Flattened membrane sacs (cisternae) with bulging ends
      2. Cis (recieving) face faces nucleus/ER, trans (shipping) face faces cell membrane
      3. Modifies, Packs, Sorts proteins destined for lysosome, secretion, plasma membrane

   6. Lysosome

      1. Membrane bound organelle filled with digestive enzymes

      2. Digest material that enter by endocytosis

      3. Removal of worn out or damaged organelles (autophagy)

      4. Self-destruction: digest cellular (autolysis) remains after cell death

         

   7. Peroxisome

      1. Membranous sac containing catabolic enzymes

   8. Cytoskeleton:

      

      1. Various proteins and structures involved in cell structure and motility

      2. Microfilaments:

         1. 2 thin helical actin fibres (7nm), cytokinesis, motility, endo/exocytosis, resists crushing

            

      3. Intermediate Filament:

         1. 5 different types (proteins), 10nm, mechanical support

      4. Microtubule

         1. 25nm, alpha and beta tubulin units, hollow shafts, shape/support, moving organelles

      5. Centrosomes

         1. Microtubule organization centre

         2. 9 microtubule triplets arranged circularly, surrounded by pericentriolar material

         3. Centrosome = centriole pair

            

2. Explain the functional importance of specific organelles relative to the functions of tissues, organs and systems of the body

   1. Nucleus: cell replication, mRNA translation for protein synthesis

      

      

   2. Mitochondria: aerobic ATP energy production

   3. Ribosome: protein synthesis

   4. ER: lipid/protein synthesis, detox (drugs and alcohol), transports molecules through cisternae, stores newly synthesized molecules

   5. Cytoskeleton: Cell shape and motility, cell division

   6. Lysosome: waste management, cell death

   7. Peroxisome: Breakdown of toxic metabolites and reactive oxidant species

   8. Plasma membrane: semi-permeability, recognition, barrier

      

      • Contains transport protein:

        • hydrophilic channel across the membrane that is selective for a particular solute

          

      • Receptors for signal transduction

        • ligand gated —> conformational change —> cascade

          

      • Attachment points to cytoskeleton and extracellular matrix

        • Elements of the cytoskeleton and ECM can anchor to membrane proteins

        • helps maintain cell shape and fix the location of certain membrane proteins

        • Cell movement or bind adjacent cells together

          

      • Enzymatic activity

        • Protein can be an enzyme

        • active site exposed to solution

        • several enzyme catalyze a sequence of metabolic reactions

          

      • Intercellular joining

        • membrane proteins of adjacent cells hooked together to form intercellular jucntions

        • Cell adhesion molecules (CAMs) provide temporary binding sites to guide cell migration and other cell-cell interactions

          

      • Cell-cell recognition

        • Some glycoproteins serve as identification tags
        • specifically recognized by other cells

      • Membrane transport

   9. Golgi: sorting, modifying, packaging of proteins destined for membrane, secretion, lysosome

   

3. Describe the fluid mosaic model of membrane structure

4. Describe the major structural features and functions of membrane junctions and projections

5. Distinguish the major events of/and differences between mitosis and meiosis and examine other (non-somatic) cell division.