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A Tour of the Cell

A Tour of the Cell

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A Tour of the Cell

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  1. A Tour of the Cell Chapter 6

  2. Objectives • Be familiar with the regions of the cell and the overall role of each region • Be familiar with the basic organelles and their function • Be familiar with the way neighboring cells can communicate

  3. Cell Types • All living organisms are made of cells • Two kinds of cells • Prokaryotic: lacks membrane bound structures other than plasma membrane • Bacteria • Eukaryotic: contains membrane bound organelles enabling compartmentalization leading to specialization • animals, plants, protists, fungi

  4. Cell Size • Limits on cell size determined by ability to perform metabolic processes • Lower: can all necessary components fit • Upper: can we regulate supplies adequately (surface to volume ratio)

  5. Regions of a Eukaryotic Cell • Nucleus: contains genetic material (DNA) necessary for cell regulation. Reference library • Cytoplasm: consists of cytosol (cell fluid) and organelles (specialized structures that carry out metabolic activities of cell) • PlasmaMembrane: contains the cell and regulates movement of materials into/out of the cell

  6. Cell Overview

  7. Nucleus • Control center of cell • Dual membrane system that fuse to form nuclear pores • DNA and Protein complexes called Chromatin • Nucleolus: region of RNA within the Nucleus

  8. Nuclear Pore Structure • To get materials into the nucleus there is a 27 Amino Acid tag (zip code) added onto molecules and are assisted by proteins called importins • To leave the nucleus exportin proteins, a specific zip code, GTP and Ran are required

  9. Import Summary

  10. Ribosomes • Sites of Protein synthesis • May be free or bound • Free make proteins typically used in the cell • Bound are attached to membrane (ER) and make proteins typically for export

  11. Endoplasmic Reticulum (ER) • Part of the endomembrane system • Smooth ER: site of lipid synthesis, detox, carbohydrate metabolism • Rough ER: site of protein synthesis (contains bound ribosomes)

  12. Golgi Apparatus“When it absolutely, positively, has to leave the cell” • Finishes, sorts, and packages manufactured products of the cell • cis: receives products from “ER” • trans: ships materials to other parts of cell (often the plasma membrane)

  13. Lysosomes • Membrane bound structures responsible for the degradation of “spent” organelles and “food” items • Contain hydrolytic enzymes

  14. Vacuoles • Membrane bound storage areas for resources • Named after the resource they contain

  15. Mitochondria, Chloroplast • Mitochondria: site of most ATP synthesis • Chloroplast: site of carbohydrate synthesis

  16. Peroxisomes • Modify molecules through redox reactions (fatty acid) • Produce peroxide as a result (H2O2) • Split into two as they grow

  17. Cytoskeletal elements • Provide structural framework for the cell • Movement of materials inside and on the surface of the cell • Microtubules • grow from centrosome • load bearing • Microfilaments • pulling forces • Intermediate filaments • pulling forces

  18. Organelles of Motility • Flagellum: moves the entire cell • Cilium (cilia): moves things along the surface of the cell

  19. Extracellular Surfaces • Most cells have a combination of proteins, lipids and sugars that form an extracellular matrix • Plants have a cell wall

  20. What distinguishes one cell’s function from another? • The quantity and type of organelles determine how the cell can function.

  21. Communication is Critical • Connections between cells are called junctions • Tight junctions: leak-proof connections between cells • Desmosomes: fasten cells together strengthening the tissue • Gap junctions: provide cytoplasmic channels between cells • Plasmodesmata: plant cell channels • In order for many cells to function as a unit (as in multicellular organisms) there must be a minimal level of communication