1. Chapter 4B A Tour of the Cell

2. Other Membranous Organelles, I Mitochondria - quantity in cell correlated with metabolic activity (the more active, the more mitochondria) Site of cellular respiration Double membranes (phospholipid); cristae/matrix Intermembrane space contain own DNA

4. Other Membranous Organelles, II Chloroplast - type of plastid Double membranous Thylakoids (flattened disks) Grana (stacked thylakoids) Stroma – gel like material around grana Photosynthesis Own DNA

6. Peroxisomes Single membrane Produce hydrogen peroxide in cells Metabolism of fatty acids; detoxification of alcohol (liver) Hydrogen peroxide then converted to water by catalase

8. The Cytoskeleton Fibrous network in cytoplasm Support, cell motility, biochemical regulation Microtubules - thickest; tubulin protein; give shape, support, transport, chromosome separation Microfilaments - thinnest; actin protein filaments; motility, cell division, shape Intermediate filaments - middle diameter; made of keratin protein; shape, nucleus anchorage

10. Centrosomes/Centrioles Centrosome - region near nucleus containing the centrioles Centrioles - nine sets of triplet microtubules in a ring;used in cell replication; only in animal cells

12. Cilia/flagella Locomotive appendages Ultrastructure: “9+2” 9 doublets of microtubules in a ring with 2 single microtubules in center Connected by radial spokes Anchored by basal body Made of dynein protein

14. Cell surfaces & junctions Cell wall – in plant, not animal cells Protection, shape, regulation Plant cell: Primary cell wall produced first Middle lamella of pectin (polysaccharide); holds cells together In some plants, a secondary cell wall forms; strong durable matrix; wood (between plasma membrane and primary cell wall)

16. Extracellular matrix (ECM) Glycoproteins - proteins covalently bonded to carbohydrate Collagen (50% of protein in human body); embedded in proteoglycan (another glycoprotein-95% carbohydrate) Fibronectins - bind to receptor proteins in plasma membrane called integrins (cell communication)

18. Intracellular junctions PLANTS: Plasmodesmata: cell wall perforations; water and solute passage in plants ANIMALS: Tight junctions: fusion of neighboring cells; prevents leakage between cells Desmosomes: riveted, anchoring junction; strong sheets of cells Gap junctions: cytoplasmic channels; allows passage of materials or current between cells