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Cell Structure and Function

Cell Structure and Function. Objectives: 1.2 1.3 1.4 1.5. Tasks a cell must carry out:. Obtain food and energy Convert energy into a useable form Carry out chemical reactions Eliminate wastes Reproduce Build structures. Prokaryote vs. Eukaryote.

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Cell Structure and Function

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  1. Cell Structure and Function Objectives: 1.2 1.3 1.4 1.5

  2. Tasks a cell must carry out: • Obtain food and energy • Convert energy into a useable form • Carry out chemical reactions • Eliminate wastes • Reproduce • Build structures

  3. Prokaryote vs. Eukaryote Eukaryotes have a membrane-bound nucleus, and organelles (which may or may not be membrane-bound) Organelle = small, specialized structure that has a specific function within the cell Pro = Before; Karyon = nucleus Eu = True The organelles work together like a team, to carry out cellular functions.

  4. Prokaryotes • Small • Unicellular • Circular DNA • No nucleus • Asexual Reproduction – Binary Fission • Motile - Flagellum

  5. EUKARYOTIC CELLULAR STRUCTURE

  6. ANIMAL CELL STRUCTURES

  7. Nucleus • Most prominent organelle • Membrane-bound • Contains the cell’s DNA Nucleolus • Special area within the nucleus where ribosomal RNA is produced.

  8. Cell membrane • Composed of a bilayer (double layer) of phospholipids. • Performs a gatekeeper function – regulates movement of substances in or out of cell.

  9. Cilia and Flagella • For locomotion • Cilia (hair-like structures) – wave-like motion.

  10. Flagella (like tails) – undulating, whip-like motion. • Movements of both cilia and flagella require ATP from the cell.

  11. Mitochondria • Converts stored chemical energy intoa form that is useable by the cell (ATP). • Mitochondria have a double membrane: inner and outer. The inner membrane is folded over many times to form cristae.

  12. Mitochondria The cristae have a very large surface area on which the ATP-forming reactions can occur.

  13. Mitochondria • Cells that require lots of energy will contain more mitochondria; e.g., liver cells; muscle cells. • Mitochondria have their own DNA

  14. Ribosomes • Two subunits: One large, one small • Composed of RNA and proteins. • Ribosomes are extremely important – they synthesize proteins. • Thousands in every cell. • Free-floating, OR • Attached to endoplasmic reticulum (rough ER)

  15. Endoplasmic reticulum Two kinds: • Rough • Smooth

  16. Rough ER • attached with ribosomes. • Proteins produced here are processed by enzymes on the inner surface of the rough ER.

  17. Rough ER (cont’d) When a protein for secretion has been passed into the ER, sections of the ER membrane can bud off to form vesicles, which then get sent to the Golgi apparatus.

  18. Smooth ER • Phospholipids are synthesized here. • Some specialized cells produce other substances in the smooth ER e.g., testosterone in the testicular cells.

  19. Golgi apparatus • The Golgi apparatus receives vesicles from the ER. • The Golgi completes the processing of the macromolecules • Makes them fully functional • Continues to separate them from the cytoplasm • Sorts them so that they get transported to the appropriate locations

  20. Lysosomes • Produced by the Golgi. • “recycling facilities” of cells. • Contain digestive enzymes to break down macromolecules or larger structures. • This breakdown provides the raw materials of new macromolecules and organelles within the cell.

  21. Cytoskeleton • A system of protein filaments that extends from the nucleus to the cell membrane. • Functions: • Provides shape to the cell, • organizes the location of organelles within the cytoplasm, • allows for movement of parts of the cell.

  22. Centrosome • Co-ordinates the activity of spindle fibres (important when the cell divides). • Contains a pair of short, cylindrical centrioles that are composed of microtubules.

  23. PLANT CELL STRUCTURES

  24. Cell wall • Composed mostly of cellulose fibres. • Surrounds the cell membrane. • Adds strength and rigidity to the cell. • Cell wall allows a cell to survive in a hypotonic or hypertonic environment.

  25. Central vacuole • Large, fluid-filled • Helps provide support to the cell wall. • May include toxins that make the cell/plant taste bad to animals.

  26. Plastids • A group of organelles that synthesizes or stores foodin plant cells. • Store starch, lipids and proteins. • Plastids contain their own DNA and ribosomes. • They also contain their own replication machinery.

  27. Chloroplasts • A type of plastid. • The chlorophyll and other machinery for photosynthesis are contained within a system of thylakoids. • Grana = Stacks of thylakoids. • Stroma = Thick fluid surrounding the grana. • This is where carbohydrates are formed during photosynthesis.

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