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Chapter 3

Biology 1000 Chapter 3 York University.docx

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Department
Biology
Course
BIOL 1000
Professor
Angelo Belcastro
Semester
Fall

Description
EVOLUTION 3.1a Characteristics of Life Displays order Harnesses and utilizes energy Respond to stimuli Maintain homeostasis Grow and develop Evolve Viruses: Are not considered alive b/c w/o a hosts cell they die and are unable to make proteins 3.1b Characteristics of Life Emergent Occur from simpler interactions Ex. Utilization of energy, ability to make proteins and membranes all interact in metabolic processes 3.2a Earth 4.6bya All components of the solar system formed at the same time, through gravitational condensation of matter in interstellar cloud (hydrogen) Intense heat and gas created planets Heat from the sun allow temperature where water exists in a liquid state 3.2c All life forms made up of nucleic acids, proteins, lipids, carbs How were they formed? Hypothesis 1: Reducing Atmosphere Atmosphere had very little Oxygen, with alot of water, hydrogen, carbon dioxide, ammonia, methane which helped make organic molecules Proposed by Aleksander Oparin and John Haldane Known as reducing atmosphere because High mound of e- and hydrogen Enter lots of reactions w/ ea other products would be complex organic molecules Today we have a oxidizing atmosphere high levels of oxygen today prevents the oxidation of other rich molecules acts as the electron acceptor and become water then there was no ozone layer back then which formed after the rise in oxygen levels this was recreated in the lab, and it worked. This experiment created amino acids Abiotic formation of formation of molecules Hypothesis 2: Deep Sea Vents Organic molecules originated in vents located in the sea floors Volcanic and tectonic activity released water nutrients rich, heated to high temperatures along with methane and H2S Hypothesis 3: Extraterrestrial Origins Organic molecules came from space Meteorites: carbonaceous chodrites, rich in organic molecules 3.2d Polymers are made through dehydration synthesis reaction Today in order to synthesis proteins, enzymes are needed How were polymers made in the absence of enzymes? Indicates much simpler processes on primordial earth Clay Hypothesis (short nucleic acid chains): Short polymers enough for proteins to serve basic functions Clay is good site for polymerization Layered structures with water and minerals available, along with stored potential energy 3.3c Ribosomes are 2/3 RNA, 1/3 protein RNA component of ribosome that synthesizes and catalyzes the incorporation of aa Could be called ribozyme Proteins are more versatile than RNA 1. Catalytic power >ribozyme 2. # of ribozymes very small 3. Aa chemically interact to create bonding, which is not possible for nucleotides DNA contains sugar deoxyribose which is difficult to synthesize DNA sequencing begins with a random removal of oxygen from ribose DNA>RNA 1. DNA is more chemically stable, hence less chance to degrade 2. 3. DNA is dble stranded, in case of mutation on one end, other end still has info on it 4. Also lasts longer 3.3d Oxidation-Reduction Food is oxidized, energy is liberated and the electrons are used to reduce other molecules Primitive: electron directly transferred to substance being reduced Not efficient In multistep process, energy is slowly released ATP may have first entered cells as organic molecule, most likely hydrolyzed to make P and ADP, to release energy Later electron transfer was used directly on ADP to make ATP, energy through bonding and unbonding 3.4a Stromalites 3.5bya Type of layered rock, formed when microorganisms bind particles of sediment together, forming thin sheets Modern Day: Group of photosynthetic bacteria, Cyanobacteria help form stromolites today Earliest known photosynthetic organisms would have taken Co2 from atmosphere to make organic molecules 3.4b Earliest Heterotrophs Obtained carbon from organic molecules Human for example from sugars, proteins, and fats Early time very little oxygen, so early heterotrophs relied on anaerobic respiration (fermentative pathways) Autotrophs Obtain carbon from environment in inorganic form (Co2) Photosynthetic Organisms: Earliest type rellied on anoxygenic photosynthesis Now this method is only used my some bacteria Anoxygenic Photosynthesis: H2S and Fe2+ are
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