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Cell Structure and Function

Cell Structure and Function

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Cell Structure and Function

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  1. Cell Structure and Function Cell Discovery and Theory

  2. The Cell • A cell is the basic unit of structure and function • Humans have trillions and trillions of cells • You can’t see cells with the naked eye

  3. Cell Dudes • Robert Hooke- 1665 • Looked at cork, saw little box-shaped structures and called it cellulae • Anton van Leeuwenhoek- late 1600s • Looked at pond water and milk and saw “beasties”

  4. Cell Dudes • Matthias Schleiden- 1838-botanist • Studied plants and concluded that all plants are made of cells • Theodor Schwann- zoologist • Concluded that all animal tissues were made of cells • Rudolph Virchow- Suggested that cells come from cells

  5. Hooke’s Microscope Hooke’s Drawing of Cork

  6. Back when… • Had to draw images • No cameras! • First images of nervous system • Maid (Harriet Cole) willed her body to Dr. Rufus Weaver (1888) • He meticulously dissected her body to analyze nervous system • Understanding blood flow • Criminals sentenced to death had option to be dissected while alive – 16th century • William Harvey 1628 – dissect live and dead animals • Heart pumps blood and then it is returned – continuous flow

  7. The Human Nervous System, 1888 • Dr. Weaver took 5 months to carefully dissect Harriet and then remove and draw the nerves! • Still on display at Hahnemann Medical College, Philadelphia, PA • Nerve tissue is real and coated; eyes are models

  8. How do we know cells come from other cells?

  9. Problem? • A compound light microscope has a 10X ocular lens and a 46X objective lens. • Where is the ocular lens? ____________________ • Where is the objective lens? _________________ • What is the total magnification ___________X

  10. Prokaryotes • 2 Kingdoms • Eubackteria • Archeabacteria • No nucleus • DNA in a central nucleoid region • Contains ribosomes • First organisms on earth

  11. Eukaryotic Cells • 4 Kingdoms • Protist (single celled) • Plants (cell wall/chloroplasts) • Animals (lack cell wall/lack chloroplasts) • Fungi (cell wall/lack chloroplasts) • Contain membrane bound organelles • Organelles are specialized structures that carry out functions

  12. The Cell Membrane • The cell membrane is selectively permeable • Some things can pass but others can’t • Cell membranes are made from a phospholipidbilayer

  13. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer PhospholipidBilayer Structure • Each phospholipid has a polar head and two nonpolar tails • Polar head is attracted to water • Nonpolar tails are repelled by water

  14. PhospholipidBilayer Function • The function is to let some things in and not others • Polar molecules do not easily pass • H2O is an exception because it is small • Allows membrane to separate environment inside from outside the cell • The plasma membrane is always in motion • Fluid mosaic model

  15. Animal Cells vs. Plant Cells • Eukaryotic cell which makes up tissues in animals • Lack cell walls and chloroplasts, and have smaller vacuoles. • Appears to be circular because of the lack of a rigid cell wall. • Eukaryotic cell that makes up plants • Cell Wall • Chloroplast • Large Vacuoles

  16. Animal Cell

  17. Plant Cell

  18. Cytoplasm • Semi-fluid material inside the plasma membrane • Consists of cytosol and the cellular organelles (all organelles except the cell nucleus) • Cytosol - fluid in which the cellular organelles are suspended

  19. Cytoskeleton • Network of long, thin protein fibers provide an anchor for organelles • Microtubules-long hollow cylinders that assist in moving substances within the cell • Microfilaments-thin threads that give the cell shape and enable the cell to move Cytoskeleton in Red and Green

  20. Nucleus • Contains genetic material (DNA) • Nuclear envelope • Nuclear pores allow substances in and out • Nucleolus in center • Very dense center

  21. Ribosomes • Produce proteins • Made of RNA and protein • Made in the nucleolus • Some float freely in the cytoplasm • Others attach to endoplasmic reticulum

  22. Endoplasmic Reticulum • Interconnected network of tubules • Rough ER • Where ribosomes attach and make proteins • Appear to create bumps and rough areas on the membrane • Smooth ER • No ribosomes • Produces complex carbohydrates and lipids

  23. Golgi Apparatus • Modifies, sorts, and packs proteins in sacs called vesicles • Vesicles fuse with plasma membrane • They release proteins which move through membrane to get outside of the cell

  24. Vacuoles • Act as temporary storage unit for materials in the cytoplasm • Store, transport, or digest food and waste • Plant cells have one large one • Animal cells have little ones

  25. Lysosomes • Vesicles that contain digestive enzymes to digest excess or worn-out organelles and food particles • They also digest bacteria and viruses that enter the cell • They are built in the Golgi apparatus.

  26. Centrioles • Microtubules • Found near nucleus • Animal Cells only • Aid in cell replication

  27. Mitochondria • Powerhouse • Converts organic materials into energy • ATP • Outer and inner membranes with lots of folds • Provides large surface area to break sugar molecule bonds (produce energy)

  28. Chloroplasts- Plant only • Capture light energy and convert it to chemical energy through photosynthesis

  29. Cell Wall • Mesh of fibers that surrounds the plasma membrane • Protects and supports the cell • Made of carbohydrate, cellulose

  30. Cilia and Flagella • Cilia- short projections that look like hairs • Move back and forth like oars on a rowboat • Move substances along surface of the cell • Flagella- longer projections that move in a whip-like motion • Both are composed of microtubules • Move cells through watery environment

  31. Cell Transport • Diffusion -net movement of particles from high concentration to low concentration • Doesn’t require energy because the particle are in motion • Dynamic equilibrium- the overall concentration does not change, but molecules are still moving randomly

  32. What affects the rate of diffusion? • What makes molecules move faster • High temperature • High Pressure • High concentration

  33. Facilitated Diffusion • Some ions and molecules can’t diffuse across the cell membrane • Facilitated diffusion – uses transport proteins to help move some molecules across the plasma membrane

  34. Osmosis • Osmosis – diffusion of water • Most cells undergo osmosis because they are surrounded by water

  35. Hyper—Hypo– Iso tonic • These are comparing words • Hypertonic -more solute than • Hypotonic- less solute than • Isotonic- same solute as • What would happen if you • Put a red blood cell in a hypertonic solution • Put a red blood cell in a hypotonic solution • Put a red blood cell in an isotonic solution

  36. Active Transport • Goes from low to high concentration • Requires Energy • ATP • Moves large substances

  37. Endocytosis • Endocytosis- moving large substances into the cell

  38. Exocytosis • Exocytosis- moving large substances out of the cell