Chapter 5 Making A Cell

Chapter 5: Making a Cell Introduction 1. Microbes define the extent of the biosphere, where there is life, there are microbes; where there are no microbes, there is no life. 2. Autocatalysis is the ability to self replicate. Growth Metabolism: Making Life from Nonlife 1. Non-living things may be chemically active on a small scale or geologically active in a grand scale, but have no role In organized events and appear inert, where as living things are result of high organized chemical reaction called metabolism, which leads to all characteristics of living things. 2. Cells utilize information embedded in their existing structures to guide reactions of synthesis and assembly that results in the production of new cells, which is made possible by four overarching principals of specific catalysts (enzymes), reaction coupling, harvesting energy and biological membranes transducer energy. 3. Reaction coupling makes individual chemical process that that necessary for life by coupling the with other favorable reactions like hydrolysis of ATP>ADP. 4. Metabolism is the sum of chemical processes in a living system, where growth metabolism is the chemical reactions necessary needed for a cell to divide and nongrowth reaction are those responsible for vital cellular activities. Framework of Growth Metabolism 1. Many bacteria are capable of rapid growth and reproduction, which is due to the structural design of prokaryotic cells where the reproduction involves a very large number of chemical reactions. 2. In E. coli nearly half of the 4200 genes encode enzymes with known functions, where many are involved in making protoplasm from glucose and inorganic salts. 3. In flowcharts here, one can change the staring material and still end up with essentially the same products, where in the case of heterotroph, it does not matter what the organic nutrient is, the end products is always a cell that heterotroph. 4. Successful production of a living cell depends not only on the chemistry of the metabolic reactions but also on the cooperative interplay of those reaction, where there are feedback loops the other controls devices that result in the production of a living cell. I. Making Two from One 1. Once a cell had successfully doubled in mass and size, having made every cellular compound and structure, the now-enlarged cell must divide into two living units through a process of binary fission. II. Assembling Cell Structure 1. Each cell must have a complex envelope and for some appendages, a nucleoid, a cytoplasm rich in polyribosomes and enzymatic machinery. 2. Assembly reaction form each of the cell’s structures out of macromolecules, where some assemble depends on enzymes, where other self assemble by condensation. 3. Assembling also involves translocating/moving molecules from their point of manufacture to their ultimate location. III. Making Macromolecules 1. Chemical composition of the major cellular structures are proteins, nucleic acids, carbohydrates, and lipids, plus hybrids of these are lipoproteins, lipopolysaccharides, and murein, all of which are made in the cell and not acquired from the environment. 2. Macromolecules are formed by the polymerization of their building blocks: amino acids, nucleotides, fatty acids, sugars, and a score of related compounds, which requires a large amount of energy in the form of ATP. [amino acid addition to polypeptide requires 4 high energy-phosphate bond, nucleotide require 2, and others] IV. Synthesizing Building Blocks

1. Are made by biosynthesis reactions, which begin with one or more of just 13 compounds, the common precursor metabolites. 2. Building blocks are usually at a more reduced state than the precursor metabolites from which they are made, where they are larger and more complex where large amount of NADPH and ATP are consumed in their synthesis. (lead bacteria to live in habitat that is nutrient rich to avoid varying genes for unnecessary enzymes) V. Fueling 1. Getting precursor metabolites, energy, and reducing power needed for biosynthesis is the function of the fueling reactions, however energy demands of the cell go well beyond the manufacture of building blocks. 2. The growth requirements for energy (ATP) and reducing power (NADPH) can be calculated in a particular instance from knowing the composition of a cell under specific growth conditions and details of its pathways of biosynthesis and polymerization, 3. All of the chemical energy is derived from organic, inorganic, or photochemical redox reactions. 4. Prokaryotes as a group can use as a sole carbon source any organic compounds in Earth, inorganic CO2 and can obtain energy and reducing power by oxidizing either inorganic or organic compounds or by harvesting energy from light. 5. Microbes that obtain their carbon from organic compounds are called heterotrophs; those using CO2 as major carbon source are called autotrophs. 6. If a chemical source is used as the source of energy and reducing power, then the prefix “chemo” is added to heterotroph or autotroph, and if light is used as source of energy “photo” is used but if it is a inorganic molecules (H2, CO, NH3, NO2, H2S, S, S2O3^2-, & Fe^2-) is used then chemoautotroph are call lithotrophs,. 7. In heterotrophs fueling starts with the entry of the organic substances that serve as sources of carbon and energy, process uses energy, whereas in autotrophs same happens, but in many cases theses are just CO2 and light or an inorganic compound, where food sources is then converted into 13 metabolites. 8. Conversion of energy, if not derived from light, into a form useful to the cell involves the oxidation of food molecules (removal of electrons from inorganic compounds or H+ atoms from organic substrates). 9. Precursor metabolites are generally more oxidized than the average building block and some of the reducing power formed in the fueling pathways must be used in biosynthesis. 10. Microbes and others use oxidation reactions to generate ATP either by substrate level phosphorylation or by proton motive force established commonly by means of electron transport, where electron is move from carrier to carrier in cell membrane down electrochemical gradient to produce H+ gradient: used to make ATP. Global Effects of Growth Metabolism 1. Earth’s biosystem is based on the metabolism of microbes. I. Earth’s Chemical Cycles 1. Each of the major element of living matter-C, N, S, & P, exists in nature in its own cyclic process in which it is constantly consumed and replenished and microbial metabolism brings about interconversions of matter that are vital in keeping polls of the major element in balance. [Necessary for life] 2. Microbes exist throughout the biosphere in huge number accounting for much of Earth’s biomass, where they have high rate of metabolism and can metabolize any naturally occurring organic compound, and as a group they are skillful at inorganic as well as organic chemical conversions. II. Bioremediation 1, Is in which living microbes are used to assist in restoring clean water and soil environments, cleanup of hazardous waste, and maintaining a sustainable balance of Earth’s geochemical and physical cycles. 2. Due to fact that microbes can degrade any naturally occurring organic compound, oxidize or reduce many inorganic compounds, and can thrive in diverse environment.

Schaechter, M., Ingtaham, J., & Neidhardt, F. C. (2006). Microbe. Washington, D.C.: ASM Press.