AP Biology Mrs Gionta SC9 The Microscopic World of Cells Cells are marvels of complexity Trillions of cell in human body Many specialized types Main tool for explorationMicroscope Microscopes as Windows on the World of Cells ID: 1047982
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1. Chapter 4 A Tour of the CellAP BiologyMrs. GiontaSC9
2. The Microscopic World of CellsCells are marvels of complexityTrillions of cell in human bodyMany specialized typesMain tool for exploration--Microscope
3. Microscopes as Windows on the World of CellsLight Microscope (LM)Visible light projected through specimenLenses enlarge the image and project to eyeView living cellsMagnification Increase in size, depends on lensResolving PowerClarity of magnified imageElectron Microscope (EM) beam of electronsScanning Electron Microscope (SEM)View cell surfacesTransmission Electron Microscope (TEM)View internal structures
4. Microscopes as Windows on the World of Cells
5. Microscopes as Windows on the World of Cells
6. The 2 Major Categories of CellsThe countless cells on earth fall into two categories:Prokaryotic cells — Bacteria and ArchaeaEukaryotic cells — plants, fungi, and animalsAll cells have several basic features.They are all bound by a thin plasma membrane.All cells have DNA and ribosomes, tiny structures that build proteins
7. The 2 Major Categories of CellsProkaryotic and eukaryotic cells have important differences. Prokaryotic cells are older than eukaryotic cells.Prokaryotes appeared about 3.5 billion years ago.Eukaryotes appeared about 2.1 billion years ago. ProkaryotesAre smaller than eukaryotic cellsLack internal structures surrounded by membranesLack a nucleusHave a rigid cell wall
8. Idealized Prokaryotic Cell
9. The 2 Major Categories of CellsEukaryotesOnly eukaryotic cells have organelles, membrane-bound structures that perform specific functions.The most important organelle is the nucleus, which houses most of a eukaryotic cell’s DNA.
10. Idealized Eukaryotic Cell
11. Overview of Eukaryotic CellsEukaryotic cells are fundamentally similar.The region between the nucleus and plasma membrane is the cytoplasm.The cytoplasm consists of various organelles suspended in fluid.Unlike animal cells, plant cells haveProtective cell wallsChloroplasts, which convert light energy to the chemical energy of food
12. Membrane StructureSeparates living cell from nonliving surroundingsRegulates traffic of chemicals in and out of cellKey to how it works is the structure
13. Plasma Membrane: Lipids & ProteinsPhospholipidsRelated to dietary fatsOnly 2 fatty acid tails not 3hydrophobicPhosphate group in 3rd position Charged, hydrophilicPhopholipid bilayer2-layered membraneProteins embedded in bilayerRegulate traffic
14. Plasma Membrane: Lipids & ProteinsFluid MosaicNot static (fluid)Diverse proteins (mosaic)Phospholipids and proteins free to drift about in the plane of the membraneIllness can result if membrane is compromisedSuperbugs: staphylococcus aureusMRSAFlesh eating disease!!
15. Cell SurfacesPlant cells have rigid cell wall surrounding plasma membraneMade of celluloseProtect the cellsMaintain cell shapesKeep cells from absorbing too much waterCells connected via channels through cell wallsJoin cytoplasm of each cell to neighborAllow water and small molecules to move between cells
16. Cell SurfacesAnimal cells lack cell wall Extracellular matrixSticky coating to hold cells togetherProtects and supports cellsCells junctionsConnect cells togtherAllow cells in tissue to function in coordinated way
17. Genetic Control of CellNucleus chief of the cellGenes store information necessary to produce proteinsProteins do most of the work of the cell
18. Structure and Function of NucleusNuclear EnvelopeDouble membrane that surrounds nucleusSimilar in structure to plasma membranePores allow transfer of materialsNucleolusProminent structureWhere ribosomes are madeChromatinFibers formed from long DNA and associated proteinsChromosomeOne chromatin fiber
19. The nucleus
20. DNA, chromatin and chromosomes
21. RibosomesResponsible for protein synthesisIn eukaryotic cells, ribosomes make in nucleus and transported into cytoplasmSuspended in fluid making proteins that remain in fluidAttached to outside of endoplasmic reticulum, making proteins incorporated into membranes or secreted by cell
22. How DNA Directs Protein ProductionDNA programs protein production in cytoplasm via mRNAmRNA exits through pores in nuclear envelope, travels to cytoplasm, and binds to ribosomesAs ribosomes move along mRNA, genetic message translated into protein with specific amino acid sequence.
23. How DNA Directs Protein ProductionDNA RNA Protein
24. The Endomembrane SystemCytoplasm of eukaryotic cells partitioned by organelle membranesSome are connected Directly by membranesIndirectly by transfer of membrane segmentsTogether form endomembrane systemIncludes nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes and vacuoles
25.
26. Endoplasmic Reticulum (ER)Main functioning facility in cellRough ERRibosomes stud the surfaceProduce membrane and secretory proteins (i.e. salivary glands)Products transferred via transport vesiclesSmooth ERLacks ribosomes on surfaceSynthesis of lipids (steroids)Helps liver detoxify drugs
27. Endoplasmic Reticulum (ER)
28. The Golgi ApparatusRefinery, warehouse and shipping centerProducts made in ER reach Golgi in transport vehiclesReceiving dock and shipping dockModifications by enzymes as products move from receiving to shipping Phosphate groups added as tags for different destinations
29. The Golgi Apparatus
30. LysosomesSac of digestive enzymes (animal cells)ProteinsPolysaccharidesFatsNucleic acidsDevelop from vesicles budding from GolgiFood vacuolesfuse with lysosomes, exposing food to enzymes for digestionSmall molecules from digestion leave the lysosome and nourish the cell.Breakdown damaged organellesSculpturing feature Digest webbing between fingers and toes
31. Lysosomes
32. VacuolesSacs that bud from ER, Golgi or plasma membranesVariety of size and functionContractile vacuoles of protists pump out excess water in the cell.Central vacuoles of plantsStore nutrientsAbsorb waterMay contain pigments or poisons
33. Vacuoles
34. Review of Endomembrane System
35. Chloroplasts and MitochondriaEnergy ConversionCellular power stations
36. Chloroplasts Photosynthetic cells of plants and algae3 compartmentsSpace between membranes that surround chloroplastStroma: thick fluid Network of disks and tubesGrana: interconnected stacks of disksSolar power pack
37. Chloroplasts
38. MitochondriaSite of cellular respirationHarvest E from food MQ and converts to ATPFound in all eukaryotic cellsStructureEnveloped by 2 membranes filled with matrixInner membrane has several infoldings (cristae)Contain DNA that encodes their own protein
39. Mitochondria
40. The CytoskeletonNetwork of fibers extending throughout cytoplasmSkeleton and musclesSupport and movement
41. Maintaining Cell ShapeSeries of fibersMicrotubulesStraight hollow tubes composed of proteinsGuide movement of chromosomes when cells divideIntermediate filaments and MicrofilamentsBoth thinner and solidAnchorage and reinforcement for organellesDynamic cytoskeleton (amoeboid movements)
42. Maintaining Cell Shape
43. Cilia and FlagellaMobile appendagesAid in movementFlagella Generally occur singlyPropel cellUndulating whiplike motionCiliaShorter and more numerous than flagellaPromote movement by back and forth motionSome function to move fluid over tissue surfaces
44. Cilia and Flagella