BIO160 - Class Notes Week 3
BIO160 - Class Notes Week 3 BIO 160
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This 7 page Class Notes was uploaded by Aenea Mead on Thursday October 13, 2016. The Class Notes belongs to BIO 160 at California Polytechnic State University San Luis Obispo taught by Jennifer Yost in Fall 2016. Since its upload, it has received 3 views. For similar materials see Diversity and History of Life in Biology at California Polytechnic State University San Luis Obispo.
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Date Created: 10/13/16
Vocabulary Metab olism: All chemical reactions that occur within an organism in order to maintain life Organic molecules: a molecule containing at least one atom of carbon Inorganic molecules: molecules containing no carbon Autotroph: organisms which use simple molecules such as CO or CH (2ow ener4y carbon) to synthesize more complex organic molecules (high energy carbon) Heterotroph: organisms which consume the organic molecules produced by autotrophs (high energy carbon) to produce more complex molecules (higher energy carbon) P hototrophs: organisms which synthesize ATP from the sunlight by undergoing photosynthesis Chemoorganotrophs: organisms which oxidize high energy organic molecules (such as sugar) to produce ATP through cellular respiration - sugars act as the electron donor Chemolithotrophs: organisms which oxidize high energy inorganic molecules (such as NH and 3 CH )4to produce ATP through cellular respiration - the inorganic molecules act as electron donors Electron Donor: molecule which gives an electron to another molecule and is oxidized E lectron Acceptor: molecule which accepts an electron from another molecule and is reduced Oxidation: Process by which a molecule loses an electron Reduction: Process by which a molecule gains an electron Electr on Transport Chain: reduction-oxidation reaction where the overall potential energy of the reactants is reduced and transformed into ATP Microbes: microscopic organisms (bacteria or archaea) ______________________________________________________________________________ ENERGY All organisms acquire and use energy!! Life Requires: 1) Source of energy to produce ATP 2) Source of carbon METHODS FOR PRODUCING ATP AND OBTAINING CARBON Energy from…. Autotrophs (primary Heterotrophs (consumers) producers) Light (phototrophs) Photoautotrophs photoheterotrophs (plants) Organic Molecules chemoorganoautotrophs Chemoorganoheterotrophs (chemoorganotrophs) (animals) Inorganic Molecules chemolithoautotrophs Chemolithotrophic (chemolithotrophs) heterotrophs Sources of Energy: ● Light ● Organic molecules (i.e. sugars) ● Inorganic molecules (i.e. ammonia) Light as an Energy Source (phototrophs): 1) Light excites an electron 2) Electron jumps to a higher orbital 3) Electron eventually falls back down to ground state 4) When it falls it releases heat and light 5) ATP and chemical energy are produced Organic Molecules as Energy Source (Chemoorganotrophs): - Sugars - Carbon based molecules are oxidized by means of cellular respiration or fermentation - ATP is produced Inorganic Molecules (c hemolithotrophs): - Ammonia (or other inorganic molecules) - High energy molecules are oxidized by means of cellular respiration - ATP is produced Cellular Respiration: Process by which a molecule with high potential energy is oxidized and the lost electron goes to a molecule with a low potential energy. The high energy molecule is the electron donor and the low energy molecule is the electron acceptor. The potential energy difference between the donor and receptor is chemical energy in the form of ATP. Molecule w/ high energy (e donor) + molecule w/ low energy (e receptor) = ATP + byproduct Different molecules produce varying amounts of ATP by cellular respiration. For example, oxygen is a very high energy electron receptor, whereas iron and nitrate do not produce as much energy. This is why it was such an important step in Earth’s history to go from using lower energy electron receptors, to being able to use oxygen and thus produce much more energy. An entire world of possibilities opened up. Currently archaea is the only known life form to produce methane. ______________________________________________________________________________ PROKARYOTIC CELLS Characteristics of a Prokaryotic Cell: ● Lack a membrane bound nucleus ● Have a cell wall ● Are all haploid (only one copy each chromosome) Today prokaryotic has come to mean “having no nucleus”. Cell Wall Composition: ● Two types of cell walls, gram + and gram - ○ Gram positive cells have an inner membrane with a thick outer cell wall ○ Gram negative cells have an inner membrane sandwiched by a thin outer cell wall and a thin inner cell wall ● Type of cell wall can be determined by a process called “gram staining” ○ Gram positive cells stain purple ○ Gram negative cells stain pink ______________________________________________________________________________ BACTERIA AND ARCHAEA Bacterial Morphological Differences: - Size (range from 0.3 micrometers to 100 micrometers) - Shapes (sphere, rod, ball, spiral / corkscrew…) - Motion (some have outer flagella to help swim, others glide, some have inner flagella to promote circular motion, etc) When did they evolve? - First cells were bacteria, which evolved 3.5 billion years ago - First fossils are of stromatolites which have been compressed overtime by layers of sediment into microbial mats What do they do? The Oxygen Revolution! - For the first 2.3 billion years of Earth’s existence there was no “free” (unbonded) oxygen anywhere to be found. The first organisms to change that are called cyanobacteria. They were the first species to perform oxygenic photosynthesis, which means that oxygen gas was one of the by-products when they underwent photosynthesis. Over time this caused oxygen levels to rise in the atmosphere. The evidence we have of this is call the Banded killing of the normal TB cells allowed the mutated cells to take over completely. When the man was given antibiotics a second time they did not work because the mutated cells, which were plentiful, were resistant to it. Bioremediation: The use of bacteria and archaea to degrade pollutants. Select strains of bacteria and archaea naturally eat plastic. Recently biologists have been experimenting with cleaning up a polluted area using these strains. One of the problems they encounter is how to manipulate which plastics the bacteria or archaea eat. If biologists were to give the strains unlimited resources they would grow exponentially and humans could lose their carefully controlled environment. This a very new study that is still being questioned and changed everyday. Where do they live? - Extremophiles: many species of bacteria and archaea are capable of not only living, but flourishing in extreme environments. They can live at very high and low temperatures, pressures and salt levels as well as both ends of the pH spectrum. - They also live in every environment in between Today studies of bacteria and archaea raise questions related to: 1) The origin of life 2) Extraterrestrial life 3) Commercial uses How bacteria and archaea reproduce and transfer genetic material: Fission: single cell splits into two daughter cells (reproduction) - Cells multiply at an exponential rate, so given unlimited resources it would not take long for bacteria or archaea to far outnumber all other life on Earth Conjugation: process by which bacteria and archaea share useful genetic material among themselves - Two bacterial or archaeal cells become connected to each other by a tube. One cell transfers selected genetic material through the tube to the other cell. - It is important to note that this is NOT a transfer from parent to offspring, but the change in the genetic code of a single organism. - Can occur between different species of bacteria and archaea - Mostly a single cell will give away a copy of their gene, but on occasion they will give away the g ene itself - Bacteria and archaea can also “purge” their bad genes out of their cell and into their surroundings
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