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Chapter 2

Chapter 2 and 13.docx

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BIOL 1000
Tamara Kelly

Chapter 2 and 13 Chapter 2: Origins of Life ch.2 (2.1b, 2.3a, 2.3d, 2.4,2.5;) Chapter 2.1b : The Fundamental Unit of Life is the Cell - Three generalizations which made up the cell theory 1. All organisms are composed of one or more cells: unicellular organisms can carry out the functions of life with one cell. The complex multicellular organisms divide the life functions 2. The cell is the smallest unit that has the properties of life: the cell properties are lost if the cell is broken apart. (functional units) 3. Cells arise only from growth and division of preexisting cells: the process of cell division even though DNA and RNA contain the info for manufacture. Chapter 2.3a: The Origin of Information System - Deoxyribonucleic Acid (DNA): is a large helical, double stranded that has 4 letter (A,T,G,C) which provides instructions for assembling components of the cell. - The process is as follows 1. The info of the DNA is copied on to the RNA 2. RNA directs the productions of protein molecules. 3. The translation of RNA into protein - Enzymes are used as catalysts in the process. - Information is preserved form generation to generation as it is passed on from parents to their offspring’s - Changes in the DNA contribute to evolutionary change Chapter 2.3d: The Development if Energy-Harnessing Reaction Pathways - Oxidation-reduction reactions in primitive cells. - In our cells, we oxidize food molecules (sugar) and use the energy(electrons) to reduce other molecules. (example: synthesizing proteins) - Oxidation in primitive cells: electrons removed in a oxidation would have been transferred directly to the substance being reduced in one-step process. The one-step process causes a lot of energy loss - Multistep process release energy slowly ( example: cellular respiration) - Adenosine triphosphate (ATP): coupling agent- links energy-releasing rxns of those requiring energy Chapter 2.4 Early Life 2.4a Earliest Evidence of Life - Stromatolites: type of layered rock tht is formed when microorganisms bind particles of sediment, forming thin sheets. - Fossil Stromatolites were formed from microbial activity. - Modern-day Stromatolites are formed by cyanobacteria (photosynthetic prokaryotes. 2.4b Could Life Have Come to Earth from Space? - Panspermia: the hypothesis that very simple forms of life are present in space and seeded Earth soon after it cooled. Two points support the extraterrestrial origin of Earth: 1. Life arose quickly after the formation of Earth. 2. Life is more resilient than previously thought. 2.4c Prokaryotes have properties common in all cells 2 types of cell: 1. Prokaryotic 2. Eukaryotic - Two types of prokaryotic : bacteria and archea - Prokaryotes don’t have a nucleus, they have a nucleiod. - All cells have a selectively permable plasma membrane: which separates the external environment from the cytoplasm - Cytoplasm has mostly water, salts and other various molecules and organelles. - Cytoplasm also has a protein complexes tht allow the controlled transport of materials in and out. - Other functions such as oxidation for synthesis of ATP. - DNA is organized as chromosomes in both P and E. 2.4d Prokaryotes display remarkable diversity. - Prokaryotes are very small in size but have a lot of diversity. - They have much less internal membrane organization in comparison to eukaryotic cells. - They have metabolic flexibility, being able to use a variety of substances as energy and carbon sources and synthesize almost all of their required organic molecules from simple inorganic raw materials. - Prokaryotes are biochemically more versatile than eukaryotes. 2.4e Oxygenic Photosynthesis and the Rise of Atmospheric Oxygen - Early prokaryotes used anaerobic respiration as geologic evidence shows that Earth lacked molecular oxygen. - There was an increase atmospheric O2 when a presence of a type of sedimentary rock called banded iron. This type of rock is formed in sediments of lakes and oceans as dissolved oxygen (O2) rea
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