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The Cellular Level

The Cellular Level. Chapter 3. The Cell Theory. Cells are the building blocks of all plants and animals. Cells are produced by the division of preexisting cells. Cells are the smallest units that perform all vital physiological functions.

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The Cellular Level

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  1. The Cellular Level Chapter 3

  2. The Cell Theory • Cells are the building blocks of all plants and animals. • Cells are produced by the division of preexisting cells. • Cells are the smallest units that perform all vital physiological functions.

  3. Each cell maintains homeostasis at the cellular level. • Homeostasis at all other levels reflects the combined and coordinated actions of many cells.

  4. I. Studying Cells • Cytology- study of the structure and function (fxn) of cells • Cell Biology- biology + chemistry + physics

  5. C. Cellular Anatomy Overview • Sex Cells (Germ/Reproductive)- sperm & egg cells

  6. 2. Somatic Cells- All other cells in the body (the focus for most of our studies this year)

  7. II. Cell Membrane • AKA Plasma Membrane or Plasmalemma • Fxns: • Physical Isolation- • Forms outer boundary of cell • Separates cell contents from extracellular fluid (interstitial fluid) • Maintains intracellular environment for homeostasis

  8. Regulation of Exchange- controls what goes in and out of a cell (semipermeable) • Sensitivity- recognizes and responds to extracellular changes • Structural Support- yup

  9. III. Cytoplasm • Cytosol- intracellular fluid • Contains dissolved material: • Nutrients • Ions • Proteins • Waste products • May contain insoluble material: • Glycogen • Lipid droplets (fat)

  10. B. Organelles • Structures that perform specific fxns within the cell • Nonmembranous Organelles • Cytoskeleton • Internal protein framework • Provides strength and flexibility • 4 components: • Microfilaments • Intermediate filaments • Thick filaments • mircrotubules

  11. Microvilli • Small projections of the cell membrane • Increase surface area for absorption • Centrioles • Found in pairs in dividing cells • Form the spindle apparatus, which is necessary for cell division

  12. Cilia • “beat” rythmically to move secretions across the cell surface (like a conveyor belt) • Ex. Cells lining the trachea • Flagella • Longer than cilia • Move a cell through a fluid • Sperm cells are the only flagellated human cells

  13. Ribosomes • Manufacture proteins • 2 kinds • Free- scattered throughout cytoplasm • Fixed- attached to endoplasmic reticulum

  14. 3. Membranous Organelles • Mitochondria • Produce energy for the cell (ATP) • The number of mitochondria per cell varies according to the cell type.

  15. Endoplasmic Reticulum (ER) • A network of membranes connected to the nuclear membrane • 4 major functions: • Synthesis- proteins, carbohydrates, lipids • Storage • Transport- “highway” of the cell • Detoxification- drugs or toxins can be absorbed & neutralized in the ER

  16. Smooth ER: • Synthesize lipids & carbohydrates • Rough ER: • Contain attached ribosomes • Modify and package proteins for transport to the Golgi apparatus

  17. Golgi Apparatus • Flattened membrane discs • 2 major functions: • Synthesize & package hormones & enzymes • Renew or modify cell membrane

  18. Lysosomes • Enzyme-filled vesicles made by the Golgi apparatus • Function in cleaning & recycling within the cell: • Damaged/old organelles • pathogens

  19. Peroxisomes • Smaller than lysosomes & contain different enzymes • Absorb & neutralize toxins (like alcohol)

  20. IV. Nucleus • Functions: • Control center of cellular operations • Stores info to control synthesis of all ~100,000 proteins in the human body • Determines the anatomy and physiology of cells by controlling what proteins are made and how much

  21. Most cells have 1 nucleus (1 exception= skeletal muscle)

  22. Structure of a typical nucleus: • Nuclear Envelope • Surrounds nucleus • Separates it from cytosol • Is a double membrane • Connected to rough endoplasmic reticulum (RER) in several places

  23. Nuclear Pores • Allow chemical communication between nucleus and cytosol • Large enough to permit the movement of ions and small molecules, but small enough to keep DNA and proteins inside

  24. Nucleoplasm • Fluid contents of nucleus • Contains the nuclear matrix (structural support) • Contains ions, enzymes, RNA and DNA

  25. Nucleolus • Synthesize ribosomal RNA • Assemble ribosomal subunits • Most prominent in cells that make large amounts of proteins (liver and muscle cells), because these cells need lots of ribosomes

  26. Sorry!  We are skipping over translation and transcription for now. We may come back to the amazing world of genetics later in second semester if there is time/interest!

  27. V. Cell Life Cycle

  28. On Your Own: Please read the sections called “Regulation of Cell Life Cycle” and “Cell Division and Cancer” It’s not super technical, so you should be able to understand it and I’m sure we’ve all known someone w/ cancer, so it’s worth reading!

  29. VI. Cell Diversity and Differentiation • All cells in your body contain all the information (DNA) needed to be any kind of human cell. • The skin cells on your big toe have the DNA necessary to be brain cells. • However, skin cells have “turned off” genes relating to anything other than skin cell functions. • This is called Differentiation.

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