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Chapter 3 “Cells” Part 2: “Cell Features”

Chapter 3 “Cells” Part 2: “Cell Features”. Cell Features. Review of the Cell Theory. The Cell Theory has 3* parts: 1) All living things are made of on or more cells . 2) Cells are the basic units of structure & function in organisms. 3) ALL cells arise from pre-existing cells.

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Chapter 3 “Cells” Part 2: “Cell Features”

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  1. Chapter 3 “Cells”Part 2: “Cell Features” Cell Features

  2. Review of the Cell Theory • The Cell Theory has 3* parts: • 1) All living things are made of on or more cells. • 2) Cells are the basic units of structure & function in organisms. • 3) ALL cells arise from pre-existing cells.

  3. Cell Size • Do large or small cells function more efficiently? • Small cells • Why ? • Because small cells can exchange substances more readily than large cells because small objects have a higher surface area-to-volume ratio as compared to larger objects. • Demonstration dye absorption in various size potato cubes.

  4. COMMON CELL TRAITS • A cell is the smallest unit that is capable of performing life functions.

  5. COMPARING CELLS • The size & shape of a cell relates to its function. (job it does)

  6. 2 main types of cells • A) Prokaryotes • Lack a true nucleus or membrane bound organells. • Memory device: Prokaryotes are “pros” & so they don’t need a nucleus. • B) Eukaryotes • Have a true nucleus & membrane bound organelles. • - • Memory device: • You are a eukaryote

  7. A) Prokaryotic Cells(proh KAYR ee yah tihk) • Do NOT have a nucleus bound by a membrane • Do NOT have organelles. • Often have a cell wall. • Oldest and simplest cells. • Chromosomes are circular & not contained in a true nucleus. • Example: Bacteria

  8. B) Eukaryotic Cells(yew KAYR ee yah tihk) • Do have a true nucleus bound by a membrane • Do have organelles with specific functions. • Animal cells do NOT have cell walls, but plants & fungi do have cell walls. . • Much larger than prokaryote cells. • Chromosomes are linear & are contained in a true nucleus. • Example: human cells

  9. Characteristics *ALL cells share. • Both prokaryotes & Eukaryotes share these traits: • 1) A cell membrane • 2) Cytoplasm • 3) Cytoskeleton • 4) *Ribosomes (*A few cells don’t have these) • 5) DNA (may be linear or circular)

  10. CELL MEMBRANE • Outer covering, protective layer around ALL cells • For cells with cell walls ,the cell membrane is inside the cell wall • Allows food, oxygen, & water into the cell & waste products out of the cell.

  11. HYDROPHILIC heads (water liking)-Attracted to the water called POLAR HYDROPHOBIC tails (water fearing)-Not attracted to the water called NON-POLAR Cell membranes are made of PHOSPHOLIPIDs A Phospholipid AS Biology. Foundation. Cell membranes and Transport

  12. BILAYERS -2 layers of phospholipids with hydrophobic tails protected inside by the hydrophilic heads. The PHOSPHOLIPID BILAYER is the basic structure of membranes. A Phospholipid Bilayer AS Biology. Foundation. Cell membranes and Transport

  13. AS Biology. Foundation. Cell membranes and Transport

  14. Fluid mosaic model Cell membranes also contain proteins within the phospholipid bilayer. This ‘model’ for the structure of the membrane is called the: FLUID MOSAIC MODEL FLUID- because individual phospholipids and proteins can move around freely within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above. AS Biology. Foundation. Cell membranes and Transport

  15. CELL WALL • protects the cell • gives shape • is made of cellulose in plants, chitin in fungi, and peptidogylcans in bacteria. • A cell wall is found in plants, algae, fungi, & most bacteria, • A cell wall is NOT found in animal cells.

  16. Cytoskeleton • Supports and gives the cell shape • Microtubules – hollow tubes of protein • Cell shape, organelle movement • Cell movement by cilia and flagella • Centrioles (animal cells only) • Microfilaments • Smaller, similar functions, muscle contraction • Work in cytoplasmic streaming

  17. CYTOPLASM • gelatin-like inside cell membrane • constantly flows • aka protoplasm

  18. NUCLEUS • Directs all cell activities • Contains instructions for everything the cell does • These instructions are found on a hereditary material called DNA • Usually the largest organelle • Only in Eukaryotes • NOT in prokaryotes

  19. NUCLEAR MEMBRANE or NUCLEAR ENVELOPE • separates nucleus from cytoplasm • Double walled with nuclear pores. • controls movement of materials in & out of nucleus

  20. NUCLEOLUS • Aka “littlenucleus” • Found in the nucleus • Made of RNA & proteins • Makes Ribosomes. • Usually stains darker in color.

  21. CHROMATIN • contains genetic code that controls cell • made of DNA & proteins

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