1. Cells… part II

2. Converting Energy n Mitochondria convert sugars and fats to NRG (ATP) with the help of oxygen – Cellular respiration n Chloroplasts convert sunlight (solar NRG) to chemical NRG – Photosynthesis n Both have: – 2 membranes – Their own DNA and ribosomes – Ability to grow and reproduce independently of the cell

3. Mitochondria quantity in cell correlated with metabolic activity location of cellular respiration double phoshoplipid membranes w/ imbedded proteins - infoldings = cristae - space inside folds = matrix (contains enzymes, DNA, etc) - intermembrane space between cristae and smooth outer membrane

4. Chloroplasts type of plastid - contain pigments and used for storage in plants - amyloplasts store starch, chromoplasts store orange pigments, etc. thylakoids (flattened disks) and grana (stacked thylakoids) stroma (fluid surrounding thylakoids)- contains enzymes, DNA, etc.

5. Peroxisomes n Single membrane n Don’t bud from endomembrane system like lysosomes n Metabolism of fatty acids; detoxification of alcohol (liver) n Creates H 2 O 2 as a byproduct of detoxification n Hydrogen peroxide then converted to water and oxygen by enzymes

6. The Cytoskeleton n Fibrous network in cytoplasm – Support for organelles – Cell motility through interaction w/ motor proteins – Biochemical regulation- sending of mechanical signals

7. Components of the Cytoskeleton n Microtubules: thickest tubulin protein shape, support, transport, chromosome separation centrosomes, centrioles, cilia, and flagella n Microfilaments : thinnest; actin protein filaments; motility, cell division, shape includes actin and myosin  Intermediate filaments: middle diameter keratin; shape, nucleus anchorage nuclear lamina and cell framework

8. Centrosomes/centrioles n Type of microtubule n Centrosome: region near nucleus n Centrioles: 9 sets of triplet microtubules in a ring; used in cell replication; only in animal cells

10. Cilia/flagella n Locomotive appendages n Ultrastructure: “9+2” 9 doublets of microtubules in a ring 2 single microtubules in center connected by radial spokes n anchored to a cell by basal body n Move using dynein protein

11. Dynein “walking” n Responsible for movement of cilia and flagella n Arms of microtubules “walk” along the adjacent ones, causing a wave-like motion

12. Microfilament Movement Thin strands of actin and thicker strands of myosin allow: n Muscles to contract n Amoebas to move w/ pseudopodia n Cytoplasm to “stream” in plant cells

13. Cell Wall n Only in plant cells n primary cell wall produced first n middle lamella of pectin (polysaccharide) forms later – holds cells together n some plants have a secondary cell wall – strong durable matrix – wood – between plasma membrane and primary wall

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

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