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Cellular Structures & Functions CYTOPLASM Image from: http://faculty.stcc.cc.tn.us/jiwilliams/labprojectsmenu.htm (Between nucleus and cell membrane) Includes ORGANELLESsmall structures with a specific function CYTOSOL-semi-fluid “goo” Image from: http://vilenski.org/science/safari/cellstructure/cytoplasm.html NUCLEUS Image from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html • Surrounded by DOUBLE membrane (Nuclear envelope) •Nuclear pores- allow molecules in & out •Contains DNA •Control center Replication (DNA → DNA) Transcription (DNA → RNA) NUCLEAR ENVELOPE Nucleus Nucleus 1 µm Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear envelope. 1 µm Ribosome 0.25 µm Close-up of nuclear envelope Figure 6.10 Pore complexes (TEM). Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nuclear lamina (TEM). NUCLEOLUS Dark spot in nucleus • Produces ribosomal RNA • Assembles ribosomes (RNA & proteins) • Image from: http://lifesci.rutgers.edu/~babiarz/histo/cell/nuc3L.jpg http://universe-review.ca/I09-08-RNA.gif DNA CHROMATINspread out in NON-dividing cells to access info CHROMOSOMEScondensed in dividing cells for easier transport Cytoskeleton Network of protein fibers supporting cell shape and anchoring organelles – – Microtubules Microfilaments RIBOSOMES Composed of two subunits that join and attach to messenger RNA Made of r-RNA & proteins Site of protein synthesis (~translation of genetic instructions to yield specific polypeptides) ENDOMEMBRANE SYSTEM Regulates protein traffic and performs metabolic functions in the cell Includes: Plasma membrane Nuclear membrane Endoplasmic reticulum Golgi apparatus Vacuoles Lysosomes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CELL MEMBRANE (also called plasma membrane) SEE HOW MEMBRANES FORM PHOSPHOLIPID BILAYER with PROTEINS Hydrophobic tails face in Hydrophilic heads face out Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Membrane Image from: © Pearson Education Inc, Publishing as Pearson Prentice Hall; All rights reserved Phospholipid image from: http://bioweb.wku.edu/courses/BIOL115/Wyatt/Biochem/Lipid/P_lipid2.htm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings FLUID MOSAIC MODEL Click here to See Fluidity Molecules in cell membranes are constantly moving and changing Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animation from: http://www.sp.uconn.edu/~terry/images/anim/fluidmem.gif CELL MEMBRANES http://vilenski.org/science/safari/cellstructure/cellmembrane.html • act as boundary • selectively permeable ~ gases & hydrophobic molecules can pass through ~ large, ionic, OR polar molecules need help (facilitated diffusion, ion channels, Na+-K+ pump, endocytosis & exocytosis) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings http://www.d.umn.edu/~sdowning/Membranes/membraneImages/jpegimages/diffusionmedium.jpg ENDOPLASMIC RETICULUM (ER) Lipid bilayer continuous with nuclear envelope Smooth ER • no ribosomes • synthesis of lipids Rough ER • with ribosomes • synthesis of secretory proteins (glycoproteins) • membrane production • compartmentalizes: serves as mechanical support, site specific protein synthesis with membrane bound ribosomes, and intracellular transport Image from: http://www.agen.ufl.edu/~chyn/age2062/lect/lect_06/5_10B.GIF Golgi apparatus (collection of Golgi bodies) •Consists of a series of flattened membrane sacs http://vilenski.org/science/safari/cellstructure/golgi.h called cisternae “UPS” of cell Modify, sort, & package molecules from ER for storage OR transport out of cell via vesicles Image from: http://www.rsbs.anu.edu Produces lysosomes Image from: http://vilenski.org/science/safari/cellstructure/golgi.h Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html See a Golgi movie EVERYTHING’S CONNNECTED! LYSOSOMES (common in animal cells but rare in plant cells) Contain hydrolytic enzymes for intracellular digestion • Food (Phagocytosis) • Damaged organelles AUTOPHAGY movie self” ~See “eating • Bacteria Recycles cell’s organic materials Helps in APOPTOSIS 18 “PROGRAMMED CELL DEATH” APOPTOSIS Embryo development Cell maintenance Signal to self destruct lost in cancer cells http://www.mgm.ufl.edu/images/bharfe/image3.jpg http://research.yale.edu/ysm/images/78.3/articles-apoptosis-cells.jpg LYSOSOMES: Uncontrolled release of lysosome contents into the cytoplasm can also cause cell death (necrosis) • APOPTOSIS (self-destruct mechanism) “cell suicide” Embryonic development Removes damaged cells Immune response Cancer cells and AIDS virus override self-destruct signals Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings WHITE BLOOD CELLS USE LYSOSOMES TO DIGEST ENGULFED BACTERIA (Phagocytosis) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings http://fig.cox.miami.edu/~cmallery/255/255ion/fig14x28.jpg CENTRIOLES Made of microtubules Appear during cell division in animal cells to pull chromosomes apart CENTRIOLES/MITOTIC SPINDLE Made of MICROTUBULES (Tubulin) Image from: http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm MITOCHONDRIA • DOUBLE MEMBRANE •Creates compartmentalization within mitochondria •Outer membrane is smooth •inner membrane highly convoluted to (increase surface area) forming cristae that contain enzymes that make ATP Images from: MITOCHONDRIA • Has own DNA • Powerplant of cell ~ site of cellular respiration – ~ burn glucose – ~ store energy as ATP • Specializes in energy capture and transformation Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings http://www.seorf.ohiou.edu/~tstork/compass.rose/photosynthesis/chloro_sun_bathing.gif CHLOROPLASTS • DOUBLE MEMBRANE •Compartmentalize structures • Contains thylakoid sacs with chlorophyll (key light trapping molecules in photosynthesis and reason why plants are green) for photosynthesis= energy capturing reactions in thylakoids produce ATP and NADPH which fuel C fixing reactions in Calvin Cycle. C fixation occurs in the stroma where molecules of CO2 are converted to carbohydrates. •Has own DNA • http://stallion.abac.peachnet.edu/sm/kmccrae/BIOL2050/Ch1-13/JpegArt1-13/04jpeg/04-28_chloroplasts_1.jpg http://media.pearsoncmg.com/bc/bc_campbell_essentials_2/cipl/04/HTML/source/04-17-chloroplast-nl.htm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Who else has a circular chromosome not found within a nucleus? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Endosymbiotic Theory http://en.wikipedia.org/wiki/Lynn_Margulis • Originally proposed in early 1900’s • Idea reintroduced in 1963 by Lynn Margulis • Suggests that engulfed prokaryotes shared symbiotic relationship with host cell • Advantages for both: ~ one supplies energy ~ other raw materials & protection Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings ENDOSYMBIOTIC THEORY See a movie about ENDOSYMBIOTIC THEORY Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings http://www.mun.ca/biology/scarr/Endosymbiosis_theory.gif Evidence for Endosymbiotic theory 1. Mitochondria and chloroplasts have circular DNA like bacteria. 2. Mitochondria and chloroplasts have ribosomes whose size and structure resemble bacterial ribosomes. 3. Mitochondria and chloroplasts replicate independently of cell division using binary fission like bacteria. 4. Inner membranes of mitochondria and chloroplasts have a composition similar to bacterial membranes. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings http://www.stchs.org/science/courses/sbioa/metenergy/flagella.jpg http://www.geocities.com/CollegePark/Lab/4551/fig12b.jpg FLAGELLA & CILIA Made of microtubules Move substances past cells Help move cells http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm http://www.sk.lung.ca/content.cfm?edit_realword=hwbreathe WHAT’S THE DIFFERENCE? CILIA • • Many short Animation from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm FLAGELLA •Few •Long WHAT’S SPECIAL ABOUT PLANT CELLS? • Cell wall • HUGE vacuoles • Chloroplasts • No centrioles http://www.windows.ucar.edu/kids_space/images/brick_wall.jpg CELL WALL Outside cell membrane Supports and protects cell PlantsCellulose makes it “sturdy” Bacteria- have peptidoglycan instead http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm VACUOLES • Huge in plants • Storage space for water, food, enzymes, waste •Helps with intracellular digestion with release of cellular waste products Image from: http://www.biologycorner.com/resources/plant_cell.gif Freshwater organisms have contractile vacuoles to control excess water in cells (HOMEOSTASIS) http://www.microscopy-uk.org.uk/mag/imgjun99/vidjun1.gif PLANT VACUOLES (Central Vacuole) Surrounded by membrane = Selectively permeable – controls what goes in & out STORAGE • Water • Stockpile proteins/inorganic ions • Deposit metabolic byproducts • Store pigments • Store defensive compounds against herbivores Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings WHAT’S DIFFERENT ABOUT BACTERIAL CELLS? • Cell wall • NO NUCLEAR MEMBRANE • DNA is circular http://www.eurekascience.com/ICanDoThat/bacteria_cells.htm • No membrane bound organelles Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings WHICH IS BIGGER? Plant cell Animal cell bacteria _________ > _____________ > ___________