BIO 201 1st Edition Lecture 7 Outline of Last Lecture I. Nucleic Acids: RNAA. RNA typesB. StructureII. Cell TheoryIII. BacteriaA. Gram+ vs. Gram-IV. EukaryotesA. Plant, Fungi, and ProtistsB. The OrganellesC. Origin of Eukaryotes D. Endosymbiosis: Mitochondria, and ChloroplastsOutline of Current Lecture I. Organelle FunctionA. CentrifugationII. The OrganellesA. The NucleusB. The Endomembrane SystemIII. George Emil PaladeCurrent LectureI. Organelle Function- By the early 1900’s biologist had observed organelles-Microscopy allows us to see nuclei but not fully, the nucleus is transparent and staining it allows for a more clear image. -The best way to see the small, transparent nucleus is by electron microscopy. A. Centrifugation- Machine that can separate organelles for studying. 1. Place sample in centrifuge tube2. Place tubes in rotor3. Place rotor in centrifugeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.4. Turn on and spin-The force on an object is a function of angular momentum (speed) and mass, therefore, centrifuging at different speeds causes object of different masses and densities to pellet in bottom of centrifuge tube. Most massive or most dense will pellet to the bottom of tube at the lowest speed. 1. Differential Centrifugation- As mass decreases speed should increase. -Relative mass: Whole cells> Cell wall & Nuclei> Mitochondria, Chloroplasts, and Lysosomes> Microsomes, Vesicles> Ribosomes -Microsomes- Not organelle, but remains of endomembrane system -Ribosomes- Protein RNA2. Density Gradient Centrifugation- Separates organelles on the basis of density.II. The Organelles- Broad categorization:-Nucleus-Mitochondria and Chloroplasts-Organelles of the Endomembrane System-Peroxisomes and Glyoxysomes-VacuolesA. The Nucleus-Separates transcription and translation related processes in Eukaryotes. -The nucleus houses genomes (rRNA in genomes) -Contains chromosomes -Location of RNA transcription -Contain nucleolus- light and electron-dense structure involved in transcription of rRNA and assembly of ribosomes-The nucleus has a double membrane structure with pores 1. RNA transcription in Eukaryotes-Multiple RNA’s transcribe simultaneously -Translation does not occur until mRNA gets out of nucleus-Disadvantage: Lag between transcription and translation, takes time. -Advantage: This lag allows for quality control of mRNA2. RNA transcription in Bacteria-bacteria does not have nuclei -Ribosome are piled up in this transcription -RNA transcription occurs in the cytoplasm, because no nuclei -Transcription and Translation aresimultaneous -Advantage: This process is fast-Disadvantage: No time for quality control of RNA B. The Endomembrane System- System of organelles that comprises most of the organelles in the cytoplasm. -Rough Endoplasmic Reticulum (RER + ribosomes)- Coated with ribosomes, protein synthesis, and core glycosylation occur here. -Smooth EndoplasmicReticulum (SER, no ribosomes)- Calcium is stored here, glycogen break down, and lipid synthesis. -Golgi Complex- Finishes protein glycosylation, sorts proteins. -Vesicles- transportation between organelles -Lysosomes- Not involved in secretion, like all of the above, but digestion and breakdown of proteins-Endosomes- Although not an organelle, the endosomes are used in the endomembrane system for ingestion of proteins.SHOULD BE ABLE TO GENERALLY RECOGNIZE:RER-Sheets of membrane coated with ribosomes, located around the nucleus, interconnected with nuclear membraneSER- Sheets of membrane without ribosomes, interconnected with RER.Golgi Complex- Located near the centrosome, not interconnected with ER. Divided in cis-, medial, and trans stacks. III. George Emil Palade (1912-2008)- Using radioactive labeling of proteins, autoradiography, and electron microscopy, George and his team discovered how secreted proteins are made and transported through the endomembrane system. The Pulse-Chase Experiment was used, they chose pancreatic cells in this experiment because they contain large amounts of digestive
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