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Transcript
The Parts of a Cell How did scientists first discover the different cell parts? History of the Cell • Hooke - the first person to see cells (1665) • van Leeuwenhock - observed living cells in pond water (1673) • Schwann - observed animals had cells (1839) • Schleiden - observed plants had cells (1845) • Virchow - predicted all cells come from other cells. (1850) The Cell Theory 1. Every living organism is made of one or more cells. 2. The cell is the smallest living unit that can perform life functions. 3. All cells arise from pre-existing cells. Endosymbiosis Theory • Eukaryotic cells evolved from a larger cell engulfing smaller bacteria cells • Evidence: Mitochondria and Chloroplasts have their own separate proteins & DNA The Prokaryotic Cell: Identify Animal Cell Parts vacuole centrioles mitochondria cytoplasm nucleolus cilia nucleus rough ER smooth ER Golgi apparatus ribosomes microtubules Cell Membrane • protects cell • semi-permeable; controls what goes in and out of cell Cytoplasm • contains everything inside the cell: salts, organic molecules, organelles, etc. Nucleus • contains DNA • makes RNA in the nucleolus Nucleolus • large dark spot within nucleus • makes ribosomes Nuclear Membrane • protects DNA • its pores control what goes in/out of nucleus • connected to endoplasmic reticulum (ER) Cytoskeleton • supports shape and movement • help anchor and transport of vesicles, organelles, etc • made of microtubules and microfilaments Ribosomes • NOT an organelle • makes proteins • can be free floating, or bound to rough ER . Endoplasmic Reticulum (ER) • make and transport materials for cell • connected to nuclear membrane Smooth ER vs Rough ER • makes lipids & vesicles; storage for detoxifying chemicals, etc • transports secretory proteins (used in cell membrane) Golgi apparatus • stack of membrane-bound vesicles • packages molecules for transport Vacuole • stores food and water, waste • bigger than vesicles Lysosome • digest food • remove waste Mitochondrion • powerhouse - makes energy for the cell • size and DNA similar to bacteria Centrioles (animal) • helps divide the cell Cilia & Flagella • moving the cell itself (flagella) • moves objects outside the cell (cilia) Chloroplast (plant) • contains the pigment chlorophyll • where photosynthesis occurs Cell Wall (plant) • supports and shapes the cell Cell Wall (bacteria) • peptidoglycan Capsule (bacteria) • surrounds and protects the cell Are all cells the same? Animal vs. Plant • cell wall • central vacuole • plastids (chloroplasts, leucoplasts, etc) • centrioles • lysosomes* Prokaryote vs. Eukaryote • no membrane-bound organelles; no nucleus • DNA in single loop; plasmid DNA • cell wall of peptidoglycan • capsule for protection • pili for sex • has membrane bound organelles; has nucleus • DNA in linear chromosomes • cell wall of cellulose • compartmentalization Nucleus • nuclear pores • nucleolus Nucleolus • makes ribosomes (2 rRNA subunits) prokaryote (70S ribosome) eukaryote (80S ribosome) Vacuole • stores food, ions, water, waste; buds off Golgi apparatus *food vacuoles *central vacuole in plants *contractile vacuoles in protozoa Golgi apparatus • cis face (toward nucleus) • trans face (toward cell membrane) Lysosome • buds off Golgi The Endomembrane system: • Related through direct continuity or by transfer on membrane segments through vesicles. • Structure of membranes is not identical • Includes: • Nuclear envelope --> Endoplasmic reticulum --> Golgi apparatus --> lysosomes --> vacuoles -->plasma membrane Peroxisome • produces H2O2; contains catalase • detoxifies alcohols and other poisons (liver cells) • self-replicating vesicle; NOT formed from Golgi Plastids • chloroplast – contain chlorophyll • amyloplast (also leucoplast in potatoes) - store starch, in roots and tubers • chromoplast – contains nonchlorophyll pigments *carrots, tomatoes Cytoskeleton • microfilaments (actin) • intermediate filaments • microtubules (tubulin) Cilia • moves the cell; moves things around the cell; respiratory & digestive tract • made of microtubules Pork vs Euk Flagella • spinning motion • flagellin proteins • waving motion • 9+2 arrangement of tubulin proteins • Cell-Cell Connections channels connect cytoplasm between cells • plasmodesmata (plants) • gap junctions (animals) Animal Cell Surface • desmosome - rivets cells together with space in between • tight junction - holds cells together Extracellular Matrix • fluids, carbohydrates and proteins The Plasma Membrane: Cell Membrane & Cell Transport Phospholipid Phospholipids in Water Cholestrol in Fluidity Cholesterol inside animal cell membranes: • At high T°, decreases fluidity by restrict movement of phospholipids • At low T°, increases fluidity by preventing close packing of phospholipids *plant cells do not have cholesterol Polar areas of protein Nonpolar areas of protein Membrane Proteins • glycocalyx - markers, glycoproteins or glycolipids enable cell-cell recognition • transport – active transport *Na-K pump • receptors – receive, transmit ECM signals • ion channels – passage of polar molecules • adhesion – attachment sites for proteins • electron transport chain – chemical reactions *photosynthesis Factors Affecting Movement • size – larger molecules, slower rate • concentration – increase [ ], increase rate • temperature – higher T°, faster rate Membrane Permeability • semi-permeable to small nonpolar molecules, small polar & uncharged molecules and gases (water, oxygen, carbon dioxide) • NOT permeable to large or charged molecules (glucose, ions like H+ or Na+) Diffusion & Osmosis --movement of water and other molecules Diffusion • movement of molecules from areas of higher concentration to areas of lower concentration Osmosis • diffusion of a solvent through a semipermeable membrane Osmosis in Living Systems hypertonic– solution with more solute isotonic - both have the same amount of solute hypotonic– solution with less solute Isotonic Hypotonic Hypertonic? Plasmolysis Plasmolysis • net loss of water from a cell to a hypertonic environment; the plasma membrane pulls away from the cell wall