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Cell Structure & Function Robert Hooke-1665 Robert Brown -1831 Cells are unit of biological structure Mattias Schleiden – ca. 1850 Discovered the "nucleus" Theodor Schwann - 1838 Coined the word “cell” Looked at cork cells Cells are the fundamental basis of life Virchow -1858 All cells come from cells 1. 2. 3. Every living organism is made up of at least one cell. Cells are the basic structural and functional units of mulicultural organisms. All cells arise from preexisting cells. 100 m 10 cm 1 cm 1 mm 100 m 10 m 1 m 10 nm 1 nm 0.1 nm Special E.M. 100 nm Mitochondrion Light Microscope Electron Microscope 1m Eukaryotic Cells Unaided eye 10 m Virus Proteins Atoms 5 Prokaryotic: Smaller, 1—5 µm No organelles No nucleus DNA in circular loop Eukaryotic: Larger, 8—100 µm Membranous organelles Nucleus DNA in linear chromosomes 6 All cells possess a plasma membrane, cytoplasm, genetic material Plasma membrane has phospholipid bilayer, embedded glycoproteins Isolates cytoplasm from environment Regulates molecular movement into and out of cell Interacts with other cells/environment Genetic material - DNA, found in the nucleus Cytoplasm Cytosol (the fluid part) Water Salts Organic monomers and polymers Organelles Animal Cell Centrioles Chloroplasts Mitochondria Golgi Nucleus Endoplasmic Reticulum Plant Cell Animal Cell Nucleolus Ribosomes Central Vacuole Smooth E.R. Cell Wall Plant Cell Protein fibers Give Cell shape; networks of intermediate filaments Help Cell movement; microfilaments & microtubules Organelle movement & suspension Amoeboid movement Muscle contraction Cell migration during development Cyclosis; pathways for vesicle migration Cell division Plasma Membrane Actin subunits Microfilaments Intermediate Filaments Mitochondrion Microtubule Endoplasmic Reticulum Tubulin subunits Tubular extensions of plasma membrane Movement of fluid, or locomotion Two functionally different types Cilia: numerous, paddle-like, synchronized Flagella: longer, fewer, more whip-like Filled with microtubules 9 pairs in periphery; 2 singlets in center “9+2” arrangement (for eukaryotes) X.S. 2 1 “Sheath” T.E.M. 3 Paramecium 4 T.E.M. Shaft Cell Membrane Base (a Centriole) 5 X.S. Shaft, x.s. Cell Membrane Microtubule Doublets Dynein Arms Central Singlets Microtubule Triplets Basal Body, x.s. Basal Body Water Water Corkscrew Movement Whipping Movement (Pulls) (Pushes) Scanning E.M. of sperm on egg Power Stroke Water Recovery Stroke Scanning E.M. of a ciliate Cell control and genetics Seen Genes in thread-like chromosomes Control production of all proteins Bounded by nuclear envelope Made up of Double lipid bilayer Pores regulate transport Not always at center of cell Nucleolus Pores Chromatin Threads (Chromosomes) Nuclear Envelope Chromatin – DNA not coiled up into a chromosome Chromosome – DNA coils around proteins called histones to create linear chromosomes Contains nucleolus of RNA Site of ribosome assembly Plasma Membrane Nuclear Pores Nucleus Nucleus Nucleoli Cell Wall Chromosomes -made of RNA and protein - Site of protein synthesis - Dark granules, (usually drawn as small circles) Folded membranes attached to nucleus Rough ER - protein synthesis Ribosomes chain amino acids into polypeptide Ribosomes on outside surface of rough ER Composed of rRNA and proteins Smooth ER Lipid synthesis Unit Membrane Ribosomes Vesicles forming Ribosomes Smooth ER Rough ER Processes material synthesized by ER Packages material and provides “address label” Distributes material in sacs called vesicles Some for inside, others outside cell Secretory vesicles merge with cell membrane Synthesis and transport of polysaccharides Material Received From ER Material Destined for Export TEM Produced by Golgi apparatus Vesicles containing hydrolytic enzymes Digestive system of cell Digest material engulfed by cell Digest and recycle damaged organelles Lysosome Endoplasmic Reticulum Destined for Export Golgi Destined for Golgi Special kidney-like organelle Draws water in from cytoplasm & expels it Important for some single-celled freshwater animals Requires ATP Paramecium sp. Expanded with Water 1 2 Expelling Water to Outside Large, water-filled spaces (cell sap) Can take up over 90% of cell volume Surrounded by tonoplast (single membrane) Functions: Storage of pigments (red/blue), acids, salts, wastes Maintain cell pressure (turgor pressure) Cytoplasm Normal Plant Cell In Salt Water Normal In Salt Water Vacuole Space between Cell Wall Cell Wall (tonoplast) and Cell Membrane “Powerhouse” of cell Numerous Glucose catabolism Bounded by double membrane Matrix / cristae Have their own DNA and ribosomes; selfreplicating Outer Membrane Inner Membrane Cristae Matrix Green plants only Captures light energy Produces carbohydrate from CO2 and H2O In cytoplasm of mostly mesophyll cells of leaf Stroma / grana (thylakoid stacks) Have their own DNA and ribosomes; selfreplicating One Granum Outer Membrane Stroma Thylakoids Inner Membrane Associated w/photosynthesis Double bilipid membrane Many functions Chloroplasts Storage of pigments Storage of photosynthetic products Double Bilipid Membrane Starch Granules Nucleoid DNA Plasmid DNA Cytosol Flagellum Capsule Plasma Membrane Cell Wall Small (<5 mircometers) Cytosol, DNA, ribosomes, cell membrane, (usually a cell wall too) Nucleoid – location of chromosome Single, circular chromosome Plasmid – small DNA ring, separate from nucleoid Flagella with a 9+0 structure (never cillia) Capsule/slime layer – polysaccharide coatings for protection Pili – protein jutting out from cell wall The end