Bio 1215 Origin of Life
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What are the four elements to form an organic molecule?
Carbon, Oxygen, Hydrogen, Nitrogen
Why was it necessary for volcanic activity to release ammonia, carbon dioxide, methane, water vapor and hydrogen gas into the atmosphere, necessary for formation of the organic molecules?
- Since all of the 4 key elements to make organic molecules is present in those it was necessary.
- Carbon Dioxide: CO2(Oxygen)
- Methane(CH4): (Carbon)
How did the absence of free oxygen (O2) in the primitive atmosphere allowed the formation of organic molecules?
- The scarcity of free oxygen on the early earth may actually have been a boon to early life forms: Strange as it may seem, oxygen is a potent poison to living organisms. Oxygen rapidly breaks down the complex molecules in cells. Human cells, and the cells of all animals, plants,
- and fungi, have complex chemical machinery that prevents oxygen—most of the time—from harming molecules within the cell.Many kinds of primitive bacteria that survive today do not have this protective machinery and die quickly when exposed to oxygen in the air. Such primitive bacteria are theholdovers from the ancient times of earth's history, and they give scientists clues to the processes that produced
Why was there intense ultra violet radiation from the sun long time ago?
Because there was no ozone layer (made out of O3) But needed O2 to make O3 but no O2
What are the 3 ways organic molecules was formed?
- 1. Volcanic activity
- 2. absence of free oxygen
- 3. sources of energy ex. lightling from intense electrical stormsm and intense uv radiation from sun
(T)How did Miller-Urey sinulate the primitive conditions of Earth in a laboratory setting?
- 1. Used these gases(CH4, CO2, NH3 and H2) to stimulate the "primitive atmosphere"
- 2. Uses electrodes discharge sparks to simulate "Lightning"
- 3. Used heated water to imitate "Ocean"
Why do they think prokaryotes were the first type of cell/bacteria ?
Because it has no ucleus, no membrane bound organelles. Its so simple, all it has is genetic material/ribosomes.
(T)rm mroe complex stable organic molecules?
By the boiling water, lava, oceanic water, primitive atmophere.
- 1. water evaporates = higher concentration
- 2. Sugar water molecules connect with rocks and creates "chemical bonds" that connect to larger molecules. (presence of clay rocks)
What is a protobionts?
Predecessors of living cells, (Before Life) basically fat droplets that holds sugars, etc.
How do Protobionts form spontaneously?
It forms by itself, concetrated in small amount of water, repels fat
(T)Protobionts are believed to be non-living yet show signs of life. How do they show signs of life?
- 1. Fat droplets can get bigger, evolve in size by allowing water and other molecuels to enter.
- 2. Eventually gets bigger and splits in half (like cell divison)
- 3. responds to stimili(charged)
(T)What does "excitable" mean?
It means when you touch the cell and the charge changes
What was the first important molecule in protobionts? and Why?(3)
- 1. Has genetic material(codes for something/has info)
- 2. Replicates itself(can carry out complemntary base pairing)
- 3. speeds up chemical reactions(like enzyme)
- RNA acts like an enzyme & DNA
Why has DNA replaced RNA as a primary genetic material?
DNA is better than RNA because RNA is not double helix and DNA is stronger. It can repair itself better.
Exlapin the autogenous model
Its when the cells form its parts on its own
- According to the autogenous model, the eukaryotes arose directly from a single prokaryote ancestor by compartmentalization of functions brought about by infoldings of the prokaryote plasma membrane. This model is usually accepted for the endoplasmic reticulum, golgi, and the nuclear membrane, and of organelles enclosed by a single membrane (such as lysosomes). According to the autogenous hypothesis, mitochondria and chloroplasts have evolved within the protoeukaryote cell by compartmentalizing plasmids (vesicles of DNA) within a pinched offinvagination of the cell membrane. Similarities between mitochondria orchloroplasts and eubacteria can be accountedfor by mosaic evolution in which the components inthecompartment evolve moreslowly than other parts of the cell, and thusretain many eubacterial features.
- Mitochondria or chloroplasts may have acquired their double-membrane status by secondary invagination or more elaborate folding of membranes.
Explain the serial endosymbiotic model
- It is believed that over millenia these mitochondria
- transferred some of their own DNA to the host cell's nucleus during the evolutionary transition from a symbiotic community to an instituted eukaryotic cell
- (called "serial endosymbiosis"). This hypothesis is thought to be possible because it is known today from scientific observation that transfer of DNA occurs between bacteria species,even if they are not closely related. Bacteria can take up DNA from their surroundings and have a limited ability to incorporate it into their own genome.
(T)Evidence for the serial endosymiotic model comes from the facts that chloroplasts and mitochondria resemble prokaryotes. Explain and compare the two
- 1. They are both similar in size.
- 2. Circular DNA and ribosomes
- 3. inner membrane of mitochondria has transport proteins/enzymes similar to the inner membrane of prokaryotes
- 4. Both can divide on its own?
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