The Tour of the Cell. Chapter 6

Transcription

1 The Tour of the Cell Chapter 6

2 The Fundamental Units of Life All living things composed of cells Cell structure correlated to cell function All cells descend from existing cells

3 Microscopy Light microscope = visible light through specimen magnified by lenses Up to 1000X

4 Electron microscopes (EMs) Scanning EM (SEM) focus beam of electrons onto surface 3-D image Transmission EM (TEM) focus beam of electrons through specimen internal structures

5 Gills of fish yeast HIV

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7 Prokaryotic cells= Archaea and Bacteria No nucleus, no membrane-bounded organelles DNA in nucleoid region 0.5 µm

8 Eukaryotic cells = Plants, Animals, Fungi, Protista DNA in nucleus Organelles Membrane bounded Cytoplasm = fluid + organelles Cytosol = fluid

9 Featured scientist: Robert Hooke

10 Micrographia was a best seller Best CLM of its time!

11 ... I could exceedingly plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular.... these pores, or cells,... were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this... The famous slide:

12 Features of cells 1. The plasma membrane = selective barrier allows passage of oxygen, nutrients, waste etc Composed of phospholipid bilayer

13 2. Surface to Volume ratio high Small cells have greater surface area relative to volume Larger organisms do not have larger cells than smaller organisms Human Rat

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16 The Eukaryotic Cell

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18 Hela cells 1. The Nucleus

19 A. Nuclear envelope (NE) Double membrane; each a bilayer Pores regulate entry and exit of molecules from nucleus

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21 B. Chromatin = DNA + proteins Chromosomes = strands of chromatin

22 C. Nucleolus Assembles ribosomes

23 D. Nucleoplasm Viscous fluid of nucleus

24 2. Ribosomes: Protein Factories Assemble amino acids into polypeptides cytosol (free ribosomes) RER/NE (bound ribosomes)

25 3. The Endomembrane System Components Nuclear envelope Endoplasmic reticulum (ER) Golgi apparatus Lysosomes Vacuoles *Plasma membrane

26 A. The Endoplasmic Reticulum >half of total membrane continuous with nuclear envelope Smooth ER lacks ribosomes 1. Synthesizes lipids 2. Metabolizes carbohydrates 3. Detoxifies poison 4. Stores calcium

27 Rough ER (RER) Ribosomes assemble proteins thread through ER lumen transport vesicles Membrane factory

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29 B. The Golgi Apparatus flattened membranous sacs called cisternae cis and trans face trans face ( shipping side of Golgi apparatus)

30 Functions of the Golgi apparatus: Modifies proteins from ER Sorts and packages protein into transport vesicles Golgi makes polysaccharides in plants

31 Nucleus Rough ER Smooth ER cis Golgi Where do the vesicles go? trans Golgi Plasma membrane

32 Virtual cell Note: Ribosome, RER, vesicle, Golgi

33 C. Lysosomes membranous sac of enzymes that digest macromolecules What do they do? recycle cell components (autophagy) get rid of phagocytosed invaders form food vacuoles How do they work?

34 phagocytosis A cell engulfs another cell to form a food vacuole lysosome fuses with food vacuole and digests molecules

35 D. Vacuoles Food vacuoles formed by phagocytosis Contractile vacuoles freshwater protists store or/and pump excess water out of cells

36 Central vacuoles found in many plant cells hold organic compounds and water

37 4. Mitochondria cellular respiration generates ATP (energy) contain mtdna all eukaryotic cells have mt Some have 1, some 1000s Outer membra ne Crist ae

38 mitochondrion

39 Mitochondria outer membrane and inner membrane fold into cristae large surface area for enzymes that synthesize ATP

40 5. Chloroplasts (plastid) found in plants and algae sites of photosynthesis green pigment chlorophyll, enzymes, other molecules

41 6. Peroxisomes detoxify catalase 2 H 2 O 2 2H 2 O + O 2 (toxic)

42 Bioflix Tour of animal cell the big picture Note: Sticky extracellular matrix Plasma membrane Cytoskeleton Mitochondria- ATP, surface area Nucleus and nuclear envelope with pores DNA and protein wrappings, code for protein Ribosome builds protein Endomembrane system = RER and SER + Golgi

43 7. Cytoskeleton Network of protein fibers organize structures and activities in cell Anchors organelles Maintains cell shape

44 Cytoskeleton interacts with motor proteins to transport cargo or for movement

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46 10 µm Column of tubulin dimers 25 nm α β Tubulin dimer

47 10 µm Actin subunit 7 nm

48 5 µm Keratin proteins Fibrous subunit (keratins coiled together) 8 12 nm

49 Vesicles in a plant cell Golgi sorting and packaging

50 8. Centrosomes and Centrioles Centrosome Centrosome microtubuleorganizing center Centrioles Microtubule 0.25 µm Longitudinal section of one centriole Cross section of the other centriole

51 centrioles animal cells only centrosome has pair centrosome

52 9. Cilia and Flagella Locomotor appendages of some cells Movement pattern controlled by microtubules Example: paramecium, algae

53 10. Extracellular materials Cells secrete materials external to plasma membrane

54 Harvard life of a cell 3 min. Can you find Cell membrane Cytoskeleton Microtubule polymerization and depolymerization A motor protein walking along the cytoskeleton Lysosomes and mt A centriole Nuclear pores with mrna leaving nucleus RER Ribosomes making proteins Vesicles budding with cis face of Golgi Proteins leaving the cell

55 A. Cell Walls of Plants Also, prokaryotes, fungi, some protists protects, maintains shape, prevents excessive uptake of water cellulose fibers + polysaccharides and protein

56 Plasmodesmata -channels between adjacent plant cells for water, nutrients..

57 B. Extracellular Matrix (ECM) of Animal No cell walls Cells Functions : Support, Adhesion, Movement, Regulation

58 Collagen EXTRACELLULAR FLUID Proteoglycan complex Fibronectin Integrins Plasma membrane Microfilaments CYTOPLASM

59 C. Intercellular Junctions Function Adherance, communication through direct physical contact

60 Gap junction connects cytoplasm to allow small molecules, ions to pass from cell to cell connexin protein