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Cell Metabolism and Mitosis • • • • Cellular Respiration Total cell metabolism Diversity of Prokaryotic Cells Review of cells Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell metabolism Larry M. Frolich, Ph.D. Biology Department, Yavapai College Catabolic pathways: break down larger molecules in to smaller ones (starch into sugar, proteins into amino acids, for example) releasing energy, most of which is lost as heat, but some can be stored as ATP Anabolic pathways: Build up larger molecules from smaller component parts (for example, assembling proteins from amino acids, assembling lipid membranes from fatty acids). These reactions use energy, usually provided by breaking high energy phosphate bonds of ATP Larry M. Frolich, Ph.D. Biology Department, Yavapai College • • • • What is cellular respiration? Occurs in the mitochondria Production of ATP in a cell Usually glucose is main “energy” molecule enters cellular respiration Includes: – – – Glycolysis Citric acid cycle Electron transport chain Larry M. Frolich, Ph.D. Biology Department, Yavapai College Oxygen and "cellular respiration” • Cells use carbohydrates to make ATP, which stores high energy bonds for anabolic pathways. • Oxygen allows for complete "burning" or catabolic breakdown of sugars in Krebs Cycle • But some ATP can be obtained in anaerobic, or pathways that are free of oxygen Larry M. Frolich, Ph.D. Biology Department, Yavapai College Glycolysis Larry M. Frolich, Ph.D. Biology Department, Yavapai College Larry M. Frolich, Ph.D. Biology Department, Yavapai College Kreb’s cycle Larry M. Frolich, Ph.D. Biology Department, Yavapai College Electron transport chain Larry M. Frolich, Ph.D. Biology Department, Yavapai College Larry M. Frolich, Ph.D. Biology Department, Yavapai College Larry M. Frolich, Ph.D. Biology Department, Yavapai College What other molecules besides glucose can be used in cellular respiration? • Other carbohydrates • Proteins • Lipids Larry M. Frolich, Ph.D. Biology Department, Yavapai College "Raw material" for anabolic or synthetic pathways • amino acids • fatty acids • nucleotides • sugars Some cells can make most of these from crude and even inorganic material. Some cells need to obtain these from environment Larry M. Frolich, Ph.D. Biology Department, Yavapai College How can a cell make ATP without oxygen? • Fermentation – Occurs in the cytoplasm – Does not require oxygen – Involves glycolysis – Makes 2 ATP and lactate in human cells – Is important in humans for a burst of energy for a short time Larry M. Frolich, Ph.D. Biology Department, Yavapai College Fermentation is oxygen-free respiration where organic molecules are ultimate electron acceptor. Many groups of bacteria are fermenters. Larry M. Frolich, Ph.D. Biology Department, Yavapai College All of cell metabolism • Cell metabolism is much more than simply making ATP, or cellular respiration, which is just how the cell has an energy supply. • What does the cell do with that energy? • The cell runs all the reactions that make it alive— see the first part of this presentation: grow, reproduce, develop, move, maintain internal homeostasis, respond to stimuli. • This involves a LOT of chemical reactions. • Next slide: most of the reactions involved in keeping the simplest of cells—an E. coli bacteria— alive! Larry M. Frolich, Ph.D. Biology Department, Yavapai College Ecocyc—database of complete E. coli metabolism Larry M. Frolich, Ph.D. Biology Department, Yavapai College What’s it all mean? • • • Every little box represents a stage in a particular chemical reaction. The sum of those reactions is the total cell metabolism—what makes the cell alive! You can visit the ecocyc database under the web links for this section as the last thing you do Remember three things: 1. every one of these reactions is catalyzed by a protein 2. The amino acid sequence for those proteins are coded for in the DNA 3. The world’s biggest super-computers are trying to figure out how, based on their unique amino acid sequence, all the different cellular proteins take on the particular shape they have, and control the particular reaction they catalyze. Get the Folding@Home Screensaver for your computer to help out. Larry M. Frolich, Ph.D. Biology Department, Yavapai College Overview of Diversity Larry M. Frolich, Ph.D. Biology Department, Yavapai College Prokaryotes—simple cells with no organelles The primitive Archaea are frequently "extreme-ophiles," including these heat-tolerant forms that live in hot springs Electron micrograph of rod-shaped bacteria--Bacillus? Larry M. Frolich, Ph.D. Biology Department, Yavapai College • Typical shapes of prokaryotic cells • Cells are tiny—as small as 1 micron Larry M. Frolich, Ph.D. Biology Department, Yavapai College Archaea • Archaea are a group of bacteria-like prokaryotes that are believed to be very close to the root of the tree of life • Characteristics of Archaea (different from bacteria): Archaea in solar evaporation ponds near San Francisco Bay--often have red or orange pigment to protect them from intense solar energy – Lack peptidoglycan in cell wall – Cell membrane lipids with branched hydrocarbon chains – AUG start codon for protein precursor is methionine (like eukaryotes) and not Nformylmethionine (like bacteria) Larry M. Frolich, Ph.D. Biology Department, Yavapai College Archaea Principally "extremophiles“ – live in harsh environments: – Thermophiles – Halophiles--highly saline habitats like Dead Sea, Great Salt Lake and solar evaporation ponds for salt production – Methanogens--obligate anaerobes in high methane environments-deep sea vents, colons of animals, sewage treatment plants Larry M. Frolich, Ph.D. Biology Department, Yavapai College Bacteria Cell Shapes and Groupings Cocci—rod-shaped bacteria Bacilli—ball-shaped bacteria Larry M. Frolich, Ph.D. Biology Department, Yavapai College • Lots of bacterial groups!! Lots of bacteria!! • closeness of disks shows similarity of rRNA sequence See course website for link to images, descriptions of bacterial groups Larry M. Frolich, Ph.D. Biology Department, Yavapai College Review of class so far Larry M. Frolich, Ph.D. Biology Department, Yavapai College The Carbon-chain Molecules of Life MOLECULE MADE OF FUNCTION Carbohydrates Simple Sugars Energy Proteins Amino Acids Fats Fatty Acids DNA/RNA Nucleotides (bases) Catalyze reactions Cell membranes Information Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cells are fundamental unit of life • Cells are the basic and fundamental unit of life • The first life was cellular life • The Molecules of Life are what cells and all their internal parts are made up of Larry M. Frolich, Ph.D. Biology Department, Yavapai College WHAT CAN EUKARYOTIC CELLS DO? WHAT STRUCTURES ARE INVOLVED? Separate inside of cell from external environment and control what substances pass across membrane Cell Membrane Produce proteins/enzymes that catalyze chemical reactions or control movement across membrane Nucleus (DNA), Ribosomes on rough endoplasmic reticulum Break down sugars to form energy which is stored in phosphate bonds of ATP Mitochondria Organize distribution of Molecules of Life (macromolecules) and ions throughout cell Internal membrane system and “cytoskeleton” (ER, lysosomes, vessicles, microtubules) Move Flagella, cilia, pseudopods Larry M. Frolich, Ph.D. Biology Department, Yavapai College A cell membrane or plasma membrane separates cell from outside world—creates ability to regulate internal environment (homeostasis) Larry M. Frolich, Ph.D. Biology Department, Yavapai College Protein synthesis • Remember that proteins control cell metabolism—how and where are they made, or synthesized in the cell? Larry M. Frolich, Ph.D. Biology Department, Yavapai College Cell metabolism Larry M. Frolich, Ph.D. Biology Department, Yavapai College What do mitochondria do and what do they look like? • A highly folded organelle in eukaryotic cells • Produces energy in the form of ATP • They are thought to be derived from an engulfed prokaryotic cell Larry M. Frolich, Ph.D. Biology Department, Yavapai College • • • • What is cellular respiration? Occurs in the mitochondria Production of ATP in a cell Usually glucose is main “energy” molecule enters cellular respiration Includes: – – – Glycolysis Citric acid cycle Electron transport chain Larry M. Frolich, Ph.D. Biology Department, Yavapai College Ecocyc—database of complete E. coli metabolism E. Coli Metaobolism website Larry M. Frolich, Ph.D. Biology Department, Yavapai College Overview of Diversity Larry M. Frolich, Ph.D. Biology Department, Yavapai College This initial review of life and cells is crucial! • Please read your book chapters, review the web links and get this part of the course. • We’ll come back to cells and how they work again and again. • I am aware this is a LOT of information! • But master this, and the rest of the course will seem easy. Larry M. Frolich, Ph.D. Biology Department, Yavapai College