BIOL 1108 Edition 1nd Exam 1 Study Guide Lectures 2 6 Lecture 2 August 22 Introduction to Prehistoric Earth Learning Objectives 1 How does abiogenesis differ from biological evolution Despite their differences how are the two concepts similar to one another 2 What was the major significance of the work of Stanley Miller Jack Szostak 3 What were some of the natural sources of biologically important molecules that were present on the early Earth before the origin of life Where did these biomolecules come from In The News Why were authorities handing out bottled water in Toledo Ohio in early August of 2014 MicrocysTIS is the algae MicrocysTIN is the toxin it produces Microcystis is a cyanobacteria algae that produces a toxin MICROCYSTIN which is contaminating the water supply in Toledo Ohio via Lake Erie Warmer temperatures and waste dumped into the lake have provided microcystis with an ideal breeding ground to bloom Microcystin causes extreme liver damage The problem with microcystin is the body does not know how to remove it Microcystin is very resilient to Ph changes and temperature fluctuations as well as many enzymes in the body PREBIOTIC EARTH Abiogenesis emergence of biotic life from abiotic resources This lies in the grey area between biology and chemistry Abiogenesis formed spontaneously through millions of years of random molecule interactions chemical evolution and biological evolution occurs spontaneously through many years of spontaneous gene mutation The earth s crust floats upon a relatively fluid mantle Mantle is constantly heated by radioactive decay from core Convection currents from fluid mantle cause crust plates to shift i e Pangea modern continents Primitive Earth s Atmosphere 80 H2O VAPOR 10 CO2 10 INERT GASES N2 CO CH4 OXYGEN O2 NOT PRESENT Present Earth s Atmosphere 77 NITROGEN N2 21 OXYGEN O2 1 WATER H2O VAPOR 0 035 CARBON DIOXIDE CO2 BIGGEST CHANGE IS THE MAJOR REDUCTION OF CARBON DIOXIDE In recent years the carbon dioxide percentage has risen from 0 035 to 0 4 This may seem like an insignificant elevation but it has a large effect on the atmosphere leads to global warming Mostly anthropogenic originates from human activity The increased levels cause CO2 dissolve in the oceans and lead to ocean acidification which would be bad for marine life Earth s atmosphere developed from outgassing in which gases are released from molten rock in the mantle of the planet by volcanic activity Comets and meteorites bring gases too HOW DID LIFE FORM Primitive chemicals had to have combined to form larger more complex molecules Primitive Earth s chemicals had to form organic molecules Molecules had to combine to form primitive cells protocells Protocells had to evolve into true cells Endosymbiosis larger organism engulfing a smaller one Life begets life Early scientists thought that life could spontaneously arise like Jan Baptista van Helmont s theory Dirty clothing wheat 21 days mice Scientists like Francisco Redi he did the experiment with the meat and the flies and how maggots did not appear if the flies could not get to the meat and Louis Pasteur he did the experiment where he had two open flasks with a broth or something that would allow bacteria to grow and one was sterilized and curved so that no outside bacteria from the air could get in and the other wasn t proved that life couldn t be spontaneous Life had to come from other forms of life STANLEY MILLER EXPERIMENT combined chemicals thought to have been present in prebiotic Earth to form life i e water ammonia carbon dioxide etc Successfully synthesized 9 20 critical amino acids required for life to exist JACK SZOSTAK earlier forms of life had a simpler biochemistry than today s organisms life probably started in a puddle not an ocean what we normally think because oceanic salt content would be so high it would destroy some precursor to membranes hydrothermal vents life s oven freezer HYDROTHERMAL VENTS It is hypothesized that the extreme heat in underwater heat vents provided substantial energy to procure life from abiotic materials Demonstrated complex organic compounds such as methane ethane and butane Can be produced via inorganic processes Lecture 3 August 25 Brief History and the Origin of Life Learning Objectives 1 Be able to explain the differences between the conventional 5 Properties definition of living things and NASA s definition of life 2 How does the concept of the RNA World solve some of the problems associated with the early stages in origin of life 3 What roles did symbiosis and lateral gene transfer LGT play in the early development of living systems In The News Why did the Liberian police use wood and wire to seal 50 000 people inside the West Point slum in Monrovia EBOLA Closely related to Marburg virus Filovirus believed to be primarily transmitted from African fruit bats Affects non human primates also Hemorrhagic fever often results in organ failure main cause of death There is no PROVEN cure for Ebola yet but a new treatment called ZMAPP has just been tested at Emory Also does ZMAPP provide immunity for life No one knows yet the doctor who went back to Africa will test it out and see What happens 1 Ebola is engulfed by macrophages and monocytes but then replicates its single stranded RNA genome within the infected cells 2 Infected cells release cytokines which actually facilitate the entry of the virus into endothelial cells that line the blood vessels 3 Viral protein interferes with the production of some important components of the human immune system like interferons 4 When the new viral particles burst the cell open they cause detachment of the host cell from its neighboring cell This leads to loss of contact between the cells causing massive hemorrhage RNA WORLD RNA molecule Polypeptides associating with RNA could aid in replication RNA can store information and can act as an enzyme Theoretical evolution of self replicating RNA Self sustaining chemical reactions known as hypercycles result in complex products being formed provided there is an input of energy It has self catalytic ability made from simpler role molecules RNA may have be able to duplicate itself by curling up into itself and acting as a catalyst RNAlike molecules have been produced in lab settings under conditions similar to those thought to exist on Earth at the advent of life This solves the paradox of needing DNA to make RNA RNA to make a protein and proteins to make DNA What are some of the shortcomings of the