Lecture 2-6 Flashcards
______ is the study of the origin, evolution, distribution, and future of life in the universe
Astrobiology
True or False: Prior to the Big Bang the entire contents of the universe (matter, energy, space, time) were contained in a very small area
True
True or False: The cause of the big bang theory is unknown,
True
True or False: As time increases the temperature in the big bang theory increases.
False, decreases
WHat are the 7 phases in the big bang theory with times?
1 10^-43 sec: Cosmos go through super fast inflation (atom to grapefruit in fraction of second)
2 10^-32 sec, 10^27C: universe is hot soup of electrons and other particles
3 10^-6 sec, 10^13C: Rapid cooling cosmos, quarks clump into protons and neutrons
4 3min, 10^8sec: Too hot to form atoms, super hot fog
5 300 000 years, 10 000C: electrons, neutrons form atoms (H & He), light can shine
6 1 billion years, -200C: Gravity makes H and He form clouds (first forming galaxies), smaller clumps form stars
7 15 billion years, -270C: Galaxies cluster the first stars die and spew elements, forms new stars and planets
How do planets form?
Accretion 4.5bya
Heating & melting
Core formation (loss of primitive atmosphere)
Cooling and crust formation (intense bombardment) 3.5 bya
Geological activity (tectonics, erosion, volcanic outgassing) present
What are some characteristics of modern day earth that make it habitable?
- water Atmosphere Oxygen (not important for some organisms to respire) Ozone layer Solid land surface – location from sun - seasons, day/night cycle - energy sources - magnetic field
What are biological characteristics of life?
- Metabolism + ability to transduce energy + use it to do work Ability to reproduce – make copy of oneself Secretion Response to stimuli Change -> acclimatize, adapt, evolve Maintain homeostasis Growth and maintenance Organization at cellular level
How do we know the estimate of earth’s age?
Barringer meteor crater
50 000 years old
______ performed by Clair Cameron Patterson estimated the earth to be ______ old .
Radiometric dating of lead isotopes, 4.5 billion years
WHat is the key event in the evolution of life, when did it occur?
3000-2700 Mya Massive increase in
oxygen concentrations
_____ are biofilms that hold sediment from several million years ago
Stromatolites
WHat are the key things to determine if it is a microfossil or rock formation?
mm-scale morphology
Carbon isotopic composition of the fossils or associated materials
Chemical composition of the objects
All 3 must be satisfied to suggest that microfossils are of biological origin
WHat is the abiotic and biotic ratio of carbon isotopes? WHy is one higher than the other?
Abiotic ratio (carbon 12:carbon 13) in mineral compounds is 89
Biotic ratio due to a preference of enzymes for Carbon 12 is 92
What are the characteristics of very early earth (4500-3800 Mya)?
No atmosphere Volcanic activity Bombardment by objects from space Outgassing of water vapour, carbon monoxide, carbon dioxide, nitrogen, hydrogen from the various layers of the planet Very hot
What are the characteristics of early earth (~3800 Mya)?
Planet starts to cool Water condenses to form oceans Volcanic activity Atmosphere starts to form-comprised of nitrogen, carbon dioxide, carbon monoxide, water vapour, hydrogen, and methane High levels of ultraviolet radiation Torrential rain and lightning
_____ is the theory that life originated elsewhere in the universe and the Earth was “seeded” with this life by meteoroids, asteroids, and planetoids
exogenesis
WHat are the 3 requirements of exogenesis?
Life must be able to survive travel through space
Life must be able to survive impacts into Earth
Life must have existed elsewhere in the universe prior to the “seeding” of Earth
How was it tested for life to travel through space (Horneck et al. 2001)?
Horneck et al. 2001 put spores of the bacterium Bacillus subtilus into space for 2 weeks
Spores exposed to UV radiation did not survive
Spores protected from UV radiation by powder of clay, rock, or meteorites
Ho was it tested if life could survive impact with earth (Burchell et al. in 2000)?
Fired projectiles coated with bacteria at 3.8/4.9 km/s at rock, glass, metal, and aerogel
Took samples from impact craters and materials ejected during the impact and cultured them
Bacteria were cultured from the ejecta from a rock surface
Therefore, this could be plausible if bacteria hit a rocky part of earth
How are we seeing if there is life elsewhere in the universe?
Sending robot probes to Mars
SETI (Search for Extra Terrestrial Intelligence)
What are the 6 hypotheses for the origin of life on Earth?
Exogenesis Abiogenesis RNA World Zinc World Hansma Mica Crystal World
______ is life arose from inanimate inorganic and organic molecules through natural processes
Abiogenesis
What two scientists believed in abiogenesis?
Charles Darwin, Alexander Oparin
What are the two requirements of abiogenesis?
Formation of monomers must be possible under the conditions of early Earth
Some explanation of transition from molecules to cells must be provided
Explain the Urey-Miller experiment to test theory of abiogenesis, what was the results?
Heat, water vapour into flask with gas (NH3 CH4 H20 H2 CO), shot electricity through it, water condensed, see what was created
22 amino acids formed
Several other organic compounds formed
Problem: Relies upon a reducing atmosphere on early Earth and certain types of gases being present
______ demonstrated prebiotic synthesis of the nucleobase adenine from hydrogen cyanide in 1959-1962
Joan Oró
How can you find something that forms a cellular structure?
Geysers could aid in forming structure (high pressure, high heat)
Fatty acids form circle because hydrophobic heads and hydrophobic tails
Opens when hits water, then seals up again, could containerize other biological monomers
What happened in the Kamimura and Kaneko 2011 experiment?
Simulation of Fast-reproducing molecules (green) and slow-reproducing molecules (red), naturally have two cells forming.
What are the two theories about organic molecules forming protocells?
Genes First-RNA world-self-replicating and catalytic RNA
Metabolism first-several hypotheses-must have organization and harness energy first, before storage of information
______ Hypothesizes that RNA predated DNA and protein synthesis
RNA world
What are the 2 requirements for the RNA world hypothesis?
Building blocks of RNA must be present (nitrogenous base and sugar-phosphate backbone)
RNA must have been able to organize itself, store information, and perform metabolism
How did they test RNA world (Powner et al., in 2009 and 2010), did it work?
were able to synthesize ribonucleotides by using prebiotic conditions and were able to tether sugar-moieties to purine precursors
Preliminary evidence that yes you can make some components of RNA in early earth conditions
What is the proposed theory on how RNA works?
RNA forms Riboenzymes catalyze RNA replication RNA catalyzes protein synthesis RNA encodes both DNA and protein Proteins catalyze cell activity
______ is an example of a metabolism first model.
Iron-Sulfur World
What is iron-sulphur world?
iron sulfide minerals provided a surface for life to develop on
Hydrothermal vents could provide energy and source of elements
______ is a theory by _____ that states Life developed in the core of the earth and is fueled by gases escaping the core.
Deep-Hot Biosphere Model, Thomas gold
scientists did not agree with
______ is the theory based on membranes water and molecules need to be in very close proximity interact
Hansma mica
True or False: Zinc World was a good idea , but been proved that zinc was used later in evolution, more prominent that iron and sulfur were first.
True
What are the 3 groups of controversial topics in the origin of life?
Heterotrophic vs. autotrophic
Genetics first vs. Metabolism first
Latecomers vs. Early invents
Cells as latecomers – container became later in life (could have lived in very small environment
Cells are early invents – container come early cause its crucial to life
What characteristics would the first life forms on Earth exhibit?
2 major hypothesis
- metabolism
- RNA replication / reproduction
What are the two domains of prokaryotes?
Bacteria, Archaea
In 1676, ______ Made his own microscope, was the first person to observe bacteria and called them ______.
Antonie van Leeuwenhoek, animalcules
______ was best known for work on diseases, invented process of Pasteurization, originator of the germ theory of disease, and disproved “spontaneous generation”
Louis Pasteur
In 1910, ______ discovered the first antibiotic based on staining of syphilis bacterium
Paul Ehrlich
In 1928, ______ was known for the discovery of penicillin, Nobel Prize 1945, and predicted in his first paper that bacteria would develop antibiotic resistance to penicillin.
Alexander Fleming
In 1977 _____ Sequenced 16S ribosomal RNA from many prokaryotes, Used the sequences to make a phylogenetic tree, and Defined the Archaea as a new domain of life as a result
Carl Woese
______ are Initially thought to be extremophiles only (thermophilic-able to withstand very high temperatures)
Believed to be extremely abundant in marine environments
DNA evidence indicates that they are present in many environments
Crenarchaeota
______ was Discovered near Pisciarelli near Naples, Italy
Grows at 80 degrees C and pH 3 in hot springs
Grows well in the lab as it is an aerobic organism
Sulfolobus solfataricus
______ Includes methanogens, halobacteria, and thermophilic anaerobes and aerobes
Euryarchaeota
______ are Found only in extremely high temperatures in hydrothermal vents
No pure culture exists
No characterization
Genome sequencing underway
Korarchaeaota
What is the one representative for the Nanoarchaeota
Nanoarchaeum equitans (obligate symbiont of its host; Ignicoccus)
______ are new division proposed in 2008
Mesophilic-live at standard temperatures
Thaumarchaeota
True or false: Gram negative have thicker peptidoglycan layer
False, gram positive
