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Cell Types, Structure, and Function

This text provides an overview of the two main types of cells, prokaryotes and eukaryotes, and their differences. It also covers the structure and function of organelles found in both plant and animal cells, as well as those specific to each type.

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Cell Types, Structure, and Function

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  1. Ch. 6 Warm-Up • What are the 2 main types of cells? Which Domains do they consist of? • List 3 ways that eukaryotes differ from prokaryotes.

  2. Ch. 6 Warm-Up • How is the size of a cell related to its function? • Name 5 organelles or cell structures and their function.

  3. Warm-Up Activity: • Pick up handout on back counter. • Complete this handout for your warm-up activity.

  4. Ch. 6 Warm-Up Compare and contrast Animal vs. Plant Cells

  5. Ch. 6 Warm-Up What is the structure & function of: • Microtubules • Microfilaments • Intermediate filaments

  6. Ch. 6 Warm-Up What is the function of: • Plasmodesmata • Gap junctions • Tight junctions • Desmosomes

  7. Chapter 6 A Tour of the Cell

  8. You Must Know • Three differences between prokaryotic and eukaryotic cells. • The structure and function of organelles common to plant and animal cells. • The structure and function of organelles found only in plant cells or only in animal cells.

  9. 2 Types of Cells: • Prokaryotes: Domain Bacteria & Archaea • Eukaryotes (Domain Eukarya): Protists, Fungi, Plants, Animals

  10. A Prokaryotic Cell (bacteria)

  11. Prokaryote Vs. Eukaryote • “before”“kernel” • No nucleus • DNA in a nucleoid • Cytosol • No organelles other than ribosomes • Small size • Primitive • i.e. Bacteria & Archaea • “true”“kernel” • Has nucleus and nuclear envelope • Cytosol • Membrane-bound organelles with specialized structure/function • Much larger in size • More complex • i.e. plant/animal cell

  12. Cell Size and Scale http://learn.genetics.utah.edu/content/begin/cells/scale/ Scale of the Universe: http://www.onemorelevel.com/game/scale_of_the_universe_2012

  13. Cells must be small to maintain a large surface area to volume ratio • Large S.A. allows  rates of chemical exchange between cell and environment

  14. Surface Area Example (Animal): Small Intestine: highly folded surface to increase absorption of nutrients • Villi: finger-like projections on SI wall • Microvilli: projections on each cell

  15. Folds  Villi  Microvilli

  16. Surface Area Example (Plant): Root hairs: extensions of root epidermal cells; increase surface area for absorbing water and minerals

  17. Nucleus • Function: control center of cell • Contains DNA • Surrounded by double membrane (nuclear envelope) • Continuous with the rough ER • Nuclear pores: control what enters/leaves nucleus • Chromatin: complex of DNA + proteins; makes up chromosomes • Nucleolus: region where ribosomal subunits are formed

  18. Nucleus • Contains DNA • Function: control center of cell • Surrounded by double membrane (nuclear envelope) • Continuous with the rough ER • Nuclear pores: control what enters/leaves nucleus • Chromatin: complex of DNA + proteins; makes up chromosomes • Nucleolus: region where ribosomal subunits are formed

  19. Ribosomes • Function: protein synthesis • Composed of rRNA + protein • Large subunit + small subunit • Types: • Free ribosomes: float in cytosol, produce proteins used within cell • Bound ribosomes: attached to ER, make proteins for export from cell

  20. Endomembrane System: Regulates protein traffic & performs metabolic functions

  21. Endoplasmic Reticulum (ER) • Network of membranes and sacs • Types: • Rough ER: ribosomes on surface • Function: package proteins for secretion, send transport vesicles to Golgi, make replacement membrane • Smooth ER: no ribosomes on surface • Function: synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca2+

  22. Endoplasmic Reticulum (ER)

  23. Golgi Apparatus • Function: synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes • Series of flattened membrane sacs (cisternae) • Cis face: receives vesicles • Trans face: ships vesicles

  24. Lysosomes • Function: intracellular digestion; recycle cell’s materials; programmed cell death (apoptosis) • Containshydrolytic enzymes

  25. Vacuoles • Function: storage of materials (food, water, minerals, pigments, poisons) • Membrane-bound vesicles • Eg. food vacuoles, contractile vacuoles • Plants: large central vacuole -- stores water, ions

  26. Parts of plant & animal cell p 108-109

  27. Mitochondria • Function: site of cellular respiration • Double membrane: outer and inner membrane • Cristae: folds of inner membrane; contains enzymes for ATP production; increased surface area to  ATP made • Matrix: fluid-filled inner compartment

  28. Chloroplasts • Function: site of photosynthesis • Double membrane • Thylakoid disks in stacks (grana); stroma (fluid) • Contains chlorophylls (pigments) for capturing sunlight energy

  29. Endosymbiont theory • Mitochondria & chloroplasts share similar origin • Prokaryotic cells engulfed by ancestors of eukaryotic cells • Evidence: • Double-membrane structure • Have own ribosomes & DNA • Reproduce independently within cell

  30. Peroxisomes • Functions: break down fatty acids; detox alcohol • Involves production of hydrogen peroxide (H2O2)

  31. Cytoskeleton: network of protein fibers • Function: support, motility, regulate biochemical activities

  32. Extracellular Matrix (ECM) • Outside plasma membrane • Composed of glycoproteins (ex. collagen) • Function: Strengthens tissues and transmits external signals to cell

  33. Intercellular Junctions (Animal cells) • Tight junctions: 2 cells are fused to form watertight seal • Desmosomes: “rivets” that fasten cells into strong sheets • Gap junctions: channels through which ions, sugar, small molecules can pass

  34. Plant Cells • Cell wall: protect plant, maintain shape • Composed of cellulose • Plasmodesmata: channels between cells to allow passage of molecules

  35. Harvard cell video http://multimedia.mcb.harvard.edu/anim_innerlife.html

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