* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 6 Cell
Survey
Document related concepts
Tissue engineering wikipedia , lookup
Cell growth wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell encapsulation wikipedia , lookup
Extracellular matrix wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Cell nucleus wikipedia , lookup
Transcript
The Tour of the Cell Chapter 6 The Fundamental Units of Life • All living things composed of cells • Cell structure correlated to cell function • All cells descend from existing cells Microscopy • Light microscope = visible light through specimen magnified by lenses – Up to 1000X • 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 • Gills of fish • HIV yeast • Prokaryotic cells= Archaea and Bacteria • No nucleus, no membrane-bounded organelles • DNA in nucleoid region 0.5 µm Eukaryotic cells = Plants, Animals, Fungi, Protista •DNA in nucleus •Organelles •Membrane bounded •Cytoplasm = fluid + organelles •Cytosol = fluid Featured scientist: Robert Hooke 16351703 Micrographia was a best seller Best CLM of its time! The famous slide: . . . 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. . . Features of cells 1. The plasma membrane = selective barrier allows passage of oxygen, nutrients, waste etc • Composed of phospholipid bilayer 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 The Eukaryotic Cell 1. The Nucleus Hela cells A. Nuclear envelope (NE) – Double membrane; each a bilayer – Pores regulate entry and exit of molecules from nucleus B. Chromatin = DNA + proteins • Chromosomes = strands of chromatin C. Nucleolus – Assembles ribosomes • D. Nucleoplasm – Viscous fluid of nucleus 2. Ribosomes: Protein Factories • Assemble amino acids into polypeptides – cytosol (free ribosomes) – RER/NE (bound ribosomes) 3. The Endomembrane System • Components – – – – – – Nuclear envelope Endoplasmic reticulum (ER) Golgi apparatus Lysosomes Vacuoles *Plasma membrane A. The Endoplasmic Reticulum • >half of total membrane • continuous with nuclear envelope – Smooth ER – lacks ribosomes 1. 2. 3. Synthesizes lipids Metabolizes carbohydrates Detoxifies poison 4. Stores calcium • Rough ER (RER) – Ribosomes assemble proteins thread through ER lumen transport vesicles – Membrane factory B. The Golgi Apparatus • flattened membranous sacs called cisternae • cis and trans face trans face (“shipping” side of Golgi apparatus) • Functions of the Golgi apparatus: – Modifies proteins from ER – Sorts and packages protein into transport vesicles Golgi makes polysaccharides in plants Nucleus Rough ER Smooth ER cis Golgi Where do the vesicles go? trans Golgi Plasma membrane • Virtual cell Note: Ribosome, RER, vesicle, Golgi 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? phagocytosis A cell engulfs another cell to form a food vacuole – lysosome fuses with food vacuole and digests molecules D. Vacuoles – Food vacuoles formed by phagocytosis – Contractile vacuoles • freshwater protists • store or/and pump excess water out of cells – Central vacuoles • found in many plant cells • hold organic compounds and water 4. Mitochondria • cellular respiration generates ATP (energy) • contain mtDNA • all eukaryotic cells have mt – Some have 1, some Outer 1000s membra ne Crist ae mitochondrion Mitochondria • outer membrane and inner membrane fold into cristae – large surface area for enzymes that synthesize ATP 5. Chloroplasts (plastid) • found in plants and algae • sites of photosynthesis – green pigment chlorophyll, enzymes, other molecules 6. Peroxisomes • detoxify 2 H2O2 (toxic) catalase 2H2O + O2 • 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 7. Cytoskeleton • Network of protein fibers organize structures and activities in cell • Anchors organelles • Maintains cell shape Cytoskeleton • interacts with motor proteins to transport cargo or for movement 10 µm Column of tubulin dimers 25 nm α β Tubulin dimer 10 µm Actin subunit 7 nm 5 µm Keratin proteins Fibrous subunit (keratins coiled together) 8–12 nm • Vesicles in a plant cell • Golgi sorting and packaging 8. Centrosomes and Centrioles Centrosome Microtubule • Centrosome Centrioles – microtubuleorganizing center Longitudinal section of one centriole 0.25 µm Cross section of the other centriole – centrioles • animal cells only • centrosome has pair centrosome 9. Cilia and Flagella • Locomotor appendages of some cells • Movement pattern controlled by microtubules • Example: paramecium, algae 10. Extracellular materials • Cells secrete materials external to plasma membrane • 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 A. Cell Walls of Plants Also, prokaryotes, fungi, some protists • protects, maintains shape, prevents excessive uptake of water • cellulose fibers + polysaccharides and protein • Plasmodesmata -channels between adjacent plant cells for water, nutrients….. B. Extracellular Matrix (ECM) of Animal Cells • No cell walls • Functions : Support, Adhesion, Movement, Regulation Collagen EXTRACELLULAR FLUID Proteoglycan complex Fibronectin Integrins Plasma membrane Microfilaments CYTOPLASM C. Intercellular Junctions • Function – Adherance, communication through direct physical contact • Gap junction connects cytoplasm to allow small molecules, ions to pass from cell to cell – connexin protein