Unit II: The Cell All organisms are made of cells, the organisms basic unit of structure and function

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Unit II: The Cell All organisms are made of cells, the organisms basic unit of structure and function. Slide 2 Size range of cells Slide 3 How We Study Cells Microscopes - light microscope - electron microscope (TEM/SEM) Slide 4 Slide 5 A Panoramic View of the Cell ProkaryoticEukaryotic + only in bacteria/archaebacteriaProtists, Fungi, Plantae, Animalia +no true nucleus/nuclear envelopetrue membrane-bound nucleus +genetic material in nucleoid regiongenetic material in nucleus +no organellesmany organelles Slide 6 Animal vs. Plant Cell Unique to Plant Cells: - cell wall - large central vacuole -Chloroplasts -Plasmodesmata Unique to Animal Cells: -Centrioles -Lysosomes - flagella and/or cilia Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 How organelles are fractionated (isolated) Slide 12 The Nucleus and Ribosomes Nucleus - enclosed by nuclear envelope - contains most of the genes that control the entire cell + DNA organized with proteins into chromatin - nucleolus Nuclear lamina protein filaments that give structure to the inner nuclear membrane Slide 13 The Nucleus and Ribosomes (cont) Ribosomes - build proteins - RNA/protein complexes - free/bound Slide 14 The Endomembrane System Includes: nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Plasma membrane* Slide 15 Endomembrane System (cont) Endoplasmic reticulum manufactures membranes two distinct regions + smooth ER - synthesis of lipids - carbohydrate metabolism - detoxify drugs/poisons - stores calcium ions + rough ER - manufacture proteins for secretion - membrane production Slide 16 Endomembrane System (cont) Golgi apparatus finishes, sorts, and ships cell products two poles + cis face + trans face Enzymes in the Golgi modify products of the ER in stages as they move through the Golgi stack from cis to trans face. Slide 17 Slide 18 Slide 19 Endomembrane System (cont) Lysosomes contain hydrolytic enzymes digestive compartments + intracellular digestion + recycle cell material + program cell destruction (apoptosis) Slide 20 Slide 21 Apoptosis programmed cell death Slide 22 Endomembrane System (cont) Vacuoles function in cell maintenance + food vacuole + contractile vacuole + central vacuole (pictured) - tonoplast Slide 23 Endomembrane System Summary Slide 24 Other Membranous Organelles Peroxisomes consume oxygen for metabolism + contain specialized teams of enzymes - peroxide-producing oxidases and catalase RH 2 + O 2 - oxidase -> R + H 2 O 2 2H 2 O 2 - catalase -> 2H 2 O + O 2 Slide 25 Mitochondria and Chloroplasts energy transformers of cells + double membranes + contain ribosomes/DNA Mitochondrial DNA is only passed on by mom Slide 26 Slide 27 Slide 28 The Cytoskeleton Cytoskeleton provides structural support for motility and regulation + network of fibers - microtubules - microfilaments - intermediate filaments Slide 29 Slide 30 Cytoskeleton (cont) Slide 31 Centrosomes Found in animal & plant cells Produce microtubules during cell reproduction Animal cells contain centrioles which contain 9 sets of 3 microtubules Slide 32 FLAGELLAFLAGELLA CILIACILIA Slide 33 Flagellum Structure Slide 34 Cell Surfaces and Junctions Cell Walls (1 & 2) cellulose fibers Plasmodesmata Middle lamella Made of pectin (sticky polysaccharide) Pectin holds cell walls together like concrete Slide 35 Cell Surfaces and Junctions ECM (Extra Cellular Matrix) meshwork of macromolecules outside plasma membrane + mostly glycoproteins (Collagen & proteoglycan) + support/anchorage (Fibronectin & integrin) Slide 36 Cell Surfaces and Junctions Tight junctions prevent fluid from moving between cell layers in a tissue Desmosomes anchor adjacent cells Gap junctions allows the movement of cytoplasm, ions, sugars, amino acids from one cell to the next Slide 37 Tight Junctions Slide 38 Desmosomes Slide 39 Gap junctions Slide 40 Slide 41 Membrane Structure and Function Collagen proteoglycan Fibronectin Slide 42 Membrane Structure and Function (cont) Plasma Membrane boundary that separates living cell from its non-living surroundings + 8 nm thick + selectively permeable + unique structure relates to function Slide 43 Phospholipid Glycerol Fatty Acid Chains Amphipathic molecule has hydrophilic & hydrophobic regions Slide 44 Hydrophilic vs Hydrophobic Slide 45 Slide 46 Slide 47 Membrane Structure and Function (cont) Fluid Mosaic Model The Fluid Quality of Membranes + held together by hydrophobic interactions - lipids/proteins drift about laterally + unsaturated hydrocarbon tails - maintain fluidity at low temperatures + cholesterol - stabilizes the membrane restrains movement at high temp. hinders close packing at low temp. Slide 48 Membrane Structure and Function (cont) Fluid Mosaic Model Membranes as Mosaics + membrane is collage of proteins - integral proteins transmembrane - peripheral proteins appendages Slide 49 Plasma membrane synthesis Slide 50 Membrane Structure and Function (cont) Functions of Membrane Proteins Transport Enzymatic Activity Signal Transduction Intercellular joining Cell-cell recognition Attachment to the cytoskeleton and ECM Slide 51 Signal Transduction with G proteins Slide 52 Types of Membrane Proteins Slide 53 Slide 54 Slide 55 Voltage Gated Ion Channels Slide 56 Glycoprotein Slide 57 Glycolipid Slide 58 Cholesterol Reduces membrane fluidity by reducing phospholipid movement Hinders solidification at low temperatures Slide 59 Cholesterol is a steroid Slide 60 Slide 61 Slide 62 Traffic Across Membranes Selective Permeability hydrophobic, small, lipid molecules pass easily across the membrane hydrophilic, large, charged (polar) molecules cannot pass easily How do cells get the materials they need inside? Slide 63 Traffic Across Membranes (cont) Passive Transport Diffusion + the tendency for molecules of any substance to spread out into the available space - concentration gradient Slide 64 Passive Transport Requires no energy Occurs due to natural concentration gradient Molecules move from high concentration to low concentration (DOWN the gradient) 3 Types Diffusion Osmosis Facilitated Diffusion Slide 65 Slide 66 Diffusion Slide 67 A.K.A. simple diffusion Movement of small molecules across a selectively permeable membrane from an area of HIGH concentration to an area of LOW concentration w/o the use of energy (DOWN the concentration gradient) e.g. O 2, CO 2, urea, & alcohol Slide 68 Traffic Across Membranes (cont) Passive Transport Osmosis + the diffusion of water - hypotonic,hypertonic, isotonic Tonicity the ability of a solution to cause a cell to gain or lose water Osmoregulation the control of water balance e.g. contractile vacuole in paramecium Slide 69 Osmosis The diffusion of WATER across a selectively permeable membrane OSMOTIC PRESSURE The pressure exerted on plasma membranes in solution Isotonic solution Hypertonic solution Hypotonic solution Slide 70 Water Potential The physical property predicting the direction in which water will flow, controlled by the solute concentration Slide 71 Water potential ( ) = pressure potential ( p ) + solute potential ( s ) Slide 72 Water potentials () are a way of measuring the free-energy of water. Water will flow spontaneously from a high potential to a low potential, like a ball rolling down a hill. () = Greek letter psi Slide 73 Physical pressure due to air & the container Slide 74

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