A TOUR OF THE CELL OVERVIEW CHAPTER 7 A TOUR OF THE CELL OVERVIEW

I. HOW WE STUDY CELLS A. MICROSCOPES PROVIDE WINDOWS TO THE WORLD OF THE CELL

II. A PANORAMIC VIEW OF THE CELL A. PROKARYOTIC AND EUKARYOTIC CELLS DIFFER IN SIZE AND COMPLEXITY ALL CELLS ARE BOUNDED BY PLASMA MEMBRANE PROKARYOTIC: CELLS WITHOUT NUCLEI OR OTHER MEMBRANE ENCLOSED ORGANELLES. Ex. BACTERIA AND ARCHAEBACTERIA EUKARYOTIC: CELLS WITH MEMBRANE ENCLOSED NUCLEI AND OTHER SPECIALIZED ORGANELLES IN THEIR CYTOPLASM Ex. ALL OTHER ORGANISMS

7.4 PROKARYOTIC CELL

B. INTERNAL MEMBRANES COMPARTMENTALIZE THE FUNCTIONS OF A EUKARYOTIC CELL THE PLASMA MEMBRANE: FUNCTIONS AS A SELECTIVE BARRIER (FIG. 7.6)

THERE ARE TWO MAIN TYPES OF EUKARYOTIC CELLS (FIG. 7.7 ANIMAL)

7.8 PLANT

III. THE NUCLEUS AND RIBOSOMES THE NUCLEUS CONTAINS A EUKARYOTIC CELL’S GENETIC LIBRARY DNA IS ORGANIZED WITH PROTEINS INTO CHROMOSOMES, WHICH EXIST AS CHROMATIN IN NONDIVIDING CELLS MACROMOLECULES PASS BETWEEN NUCLEUS AND CYTOPLASM THROUGH PORES IN THE NUCLEAR ENVELOPE

7.9 NUCLEUS & ENVELOPE

B. RIBOSOMES BUILD A CELL’S PROTEINS FREE RIBOSOMES IN THE CYTOSOL, AND BOUND RIBOSOMES ON THE OUTSIDE OF THE ENDOPLASMIC RETICULUM, SYNTHESIZE PROTEINS (FIG. 7.10)

IV. THE ENDOMEMBRANE SYSTEM DEFINITION: THE COLLECTION OF MEMBRANES INSIDE AND AROUND A EUKARYOTIC CELL, RELATED EITHER THROUGH DIRECT PHYSICAL CONTACT OR BY THE TRANSFER OF MEMBRANOUS VESICLES

CISTERNAE: MEMBRANE ENCLOSED COMPARTMENTS. A. THE ENDOPLASMIC RETICULUM MANUFACTURES MEMBRANES AND PERFORMS MANY OTHER BIOSYNTHETIC FUNCTIONS CONTINOUS WITH THE NUCLEAR ENVELOPE, THE ENDOPLASMIC RETICULUM (ER) IS A NETWORK OF CISTERNAE. CISTERNAE: MEMBRANE ENCLOSED COMPARTMENTS. TRANSPORT VESSICLE: DISTRIBUTES ER’S PRODUCTS TYPES OF ENDOPLASMIC RETICULUM SMOOTH ER: LACKS RIBOSOMES; SYNTHESIZES STEROIDS, METABOLIZES CARBS. ROUGH ER: HAS BOUND RIBOSOMES; PRODUCES PROTEINS

7.11 ENDOPLASMIC RETICULUM

B. THE GOLGI APPARATUS FINISHES, SORTS, AND SHIPS CELL PRODUCTS STACKS OF SEPARATE CISTERNAE MAKE UP THE GOLGI PARTS OF GOLGI APPARATUS CIS FACE: RECEIVES SECRETORY PROTEINS FROM THE ER IN TRANSPORT VESSICLES TRANS FACE: MODIFIES, SORTS AND RELEASES PROTEINS IN TRANSPORT VESSICLES

7.12 GOLGI APPARATUS

C. LYSOSOMES ARE DIGESTIVE COMPARTMENTS LYSOSOMES ARE MEMBRANOUS SACS OF HYDROLYTIC ENZYMES FUNCTION: BREAKDOWN CELL MACROMOLECULES FOR RECYCLING (7.13)

D. VACUOLES HAVE DIVERSE FUNCTIONS IN CELL MAINTENANCE A PLANT CELL’S CENTRAL VACUOLE FUNCTIONS IN STORAGE, WASTE DISPOSAL, CELL GROWTH, AND PROTECTION

V. OTHER MEMBRANOUS ORGANELLES A. MITOCHONDRIA AND CHLOROPLASTS ARE THE MAIN ENERGY TRANSFORMERS OF CELLS MITOCHONDRIA: SITE OF CELLULAR RESPIRATION IN EUKARYOTES STRUCTURE: OUTER MEMBRANE AND INNER MEMBRANE FOLDED INTO CRISTAE

7.17 MITOCHONDRIA

CHLOROPLASTS: A TYPE OF PLASTID, CONTAINS CHLOROPHYLL AND OTHER PIGMENTS, WHICH FUNCTION IN PHOTOSYNTHESIS STRUCTURE: TWO MEMBRANES SURROUND THE FLUID STROMA, WHICH CONTAINS THYLAKOIKS, OFTEN STACKED IN GRANA DEFINITIONS: CRISTAE: AN INFOLDING OF THE INNER MEMBRANE OF A MITOCHONDRION, THAT HOUSES THE ENZYME CATALYZING THE SYNTHESIS OF ATP PLASTIDS: ONE OF A FAMILY OF CLOSELY RELATED PLANT ORGANELLES, INCLUDIND CHLOROPLASTS, CHROMOPLASTS, AND AMYLOPLASTS STROMA: THE FLUID OF THE CHLOROPLAST SURROUNDING THE THYLAKOID MEMBRANE THYLAKOIDS: A FLATTENED MEMBRANE SAC INSIDE THE CHLOROPLAST GRANA: A STACKED PORTION OF THE THYLAKOID MEMBRANE IN THE CHLOROPLAST

7.18 CHLOROPLAST

C. PEROXISOMES CONSUME OXYGEN IN VARIOUS METABOLIC FUNCTIONS PEROXISOMES: ORGANELLES THAT BREAK DOWN VARIOUS SUBSTANCES; PRODUCE H202 AS WASTE

VI. THE CYTOSKELETON A. PROVIDES STRUCTURAL SUPPORT TO CELLS FOR CELL MOTILITY AND REGULATION STRUCTURE: MADE OF MICROTUBULES, MICROFILAMENTS, AND INTERMEDIATE FILAMENTS

7.20 CYTOSKELETON

MICROTUBULES: HOLLOW CYLINDERS; SHAPE THE CELL, GUIDE MOVEMENT OF ORGANELLES, AID CHROMOSOME SEPARATION IN DIVIDING CELLS

CILIA AND FLAGELLA: MOTILE APPENDAGES CONTAINING MICROTUBULES DOUBLETS

MICROFILAMENTS: THIN RODS BUILT FROM THE PROTEIN ACTIN; FUNCTION IN MUSCLE CONTRACTION INTERMEDIATE FILAMENTS: SUPPORT CELL SHAPE AND ORGANELLES IN PLACE

VII. CELL SURFACES AND JUNCTIONS A. PLANT CELLS ARE ENCASED BY CELL WALLS PLANT CELL WALLS ARE COMPOSED OF CELLULOSE FIBERS EMBEDDED IN OTHER POLYSACCHARIDES AND PROTEIN

7.28 PLANT CELL WALLS

B. INTERCELLULAR JUNCTIONS HELP INTEGRATE CELLS INTO HIGHER LEVELS OF STRUCTURE AND FUNCTION IN PLANTS PLASMODESMATA: CYTOPLASMIC CHANNELS THAT PASS THROUGH ADJOINING CELL WALLS IN ANIMALS TIGHT JUNCTIONS: INTERCELLULAR JUNCTION THAT PREVENTS LEAKAGE OF MATERIAL BETWEEN CELLS DESMOSOMES: FUNCTIONS AS AN ANCHOR; ACT AS SPOT WELDS TO HOLD TOGETHER TISSUES THAT UNDERGO CONSIDERABLE STRESS EX. SKIN/ HEART TISSUE GAP JUNCTIONS: ALLOWS THE PASSAGE OF MATERIAL OR CURRENT BETWEEN CELLS (IONS AND SMALL MOLECULES) ; PREVENTS CYTOPLASMS OF EACH CELL FROM MIXING

7.30 INTERCELLULAR JUNCTIONS IN ANIMALS