origin o life Flashcards
What do we know about the earth?
- Earth is about 4.65 billion years old (from geological evidence)
- For the first billion years, we have no record of life on the planet.
Gases in the early atmosphere?
- H2 CO2 N2 H2S H2O CH4 NH3
- may have been unable to sustain life
Were organic macromolecules able to form under the conditions on the early Earth?
-Aleksandr Oparin’s hypothesis says YES
-There is no fundamental
difference between a living
organism and lifeless matter.
-characteristic of life must have arisen in the process of the evolution of matter
What did Stanley Miller prove?
- it is possible that organic molecules (which appear in creatures) can be created in early atmosphere
- in the 1950s
- after one week 18% of methane molecules convert into biomolecules
What is the phylogenetic tree?
-phylogenetic tree or evolutionary tree is a branching diagram or “tree” showing the evolutionary relationships among various biological species or other entities
Name some procaryotes and eukaryotes
- prokaryotes= bacteria, archaea
- eukaryotes= protists, plants, fungi, animals
What is closer to humans? Fungi, animals, bacteria
-human> animals> fungi> bacteria
How were the Earth’s only organisms (for the first two billion years)?
-microscopic, unicellular (einzellig) and aquatic
How does the first fossil look like?
- 3.5 billion years old
- Resembling Bacteria, embedded in rocks from Western Australia
What are some rich sources for early prokaryote fossils?
-Stromatolites: fossilized layered microbial mats
Sediments from ancient hydrothermal vent habitats (alten hydrothermalen Abzugsgebiete)
What was the earth like 3.5 to 4.0 billion years ago?
- very hot from excessive volcanic activity
- numerous meteor impacts
- high solar radiation
- very little oxygen-consequently no ozone layer to protect from…
- high ultraviolet (UV) radiation
- atmosphere of H2O, H2, CH4, NH3, CO2, CO,N2, H2S
- A reducing atmosphere = electron-adding
What is reducing atmosphere?
-A reducing atmosphere is a gaseous environment with a lessened amount of oxygen as a free-form vapor (Dampf) as a single unit or in a mixture. It often contains other reactive gaseous elements or compounds such as hydrogen or nitrogen.
Name important steps in creation of life
- Nonbiological synthesis of organic compounds in nonoxidizing atmosphere
- Polymerization by removal of water from chemical joints of monomers
- Survival advantage of protocells that can make polymers
- Evolution of metabolic chains from back-to-front
- Natural selection for objects that have genetic apparatus (nucleic acids) for remembering metabolic recipes that can pass down that apparatus (DNA) to daughter cells
- Importance of sex, eukaryotic cells, and cell differentiation
What was the Aristotle’s idea?
-Proposed the theory of spontaneous generation
(abiogenesis):
->Idea that living things can arise from nonliving matter
( lasted almost 2000 years)
Give examples for abiogenesis
- muddy soil gave rise to the frogs
- mice came from the moldy grain (schimmeliges Getreide)
How was the disproving of the spontaneous generation?
-Francesco Redi (1668)
-Unsealed – maggots on meat
Sealed – no maggots on meat
Gauze (Drahtgeflecht) – few maggots on gauze, none on meat
What did Anton Leeuwenhoek find (1674) ?
- began making and looking through simple microscopes
- examined water and visualized tiny animals, fungi (Pilze), algae, and single celled protozoa; “animalcules” then called microbes
What did John Needham (1745) show?
- Showed that microorganisms flourished (aufblühen) in various soups that had been exposed to the air
- Claimed that there was a “life force” present in the molecules of all inorganic matter, including air and the oxygen in it, that could cause spontaneous generation to occur
What was the problem with John Needham’s thesis?
-People didn’t realize bacteria were already present in Needham’s soups
-Needham didn’t boil long enough to kill the microbes
(-broth appeared clear after boiling (but only till you wait))
Describe Lazzaro Spallanzani’s experiment (1765)
- heated broth let it cool and open , waited and bacteria appeared
- heated broth let flask sealed , waited nothing grew, opened flask -> bacteria appeared
How do microbes appear (history)?
- By 1860, Paris Academy of Sciences offered a prize for any experiments that would help resolve this conflict
- The prize was claimed in 1864 by Louis Pasteur (disproved spontaneous generation in microscopic organisms)
How do microbes appear (describe the Pasteur’s problem)?
- Hypothesis: Microbes come from cells of organisms on dust particles in the air; not the air itself
- Pasteur put broth into several special S-shaped flasks ( no growth
- boil+ break stem -> microbial growth
What is the result of Pasteur*s problem?
- Pasteur’s S-shaped flask kept microbes out & let air in
- Proved microbes only come from other microbes (life from life) -> biogenesis
Which came first, proteins
or nucleic acids?
-Need proteins to perform polymerization reactions in presence of water; need nucleic acids to remember how to make proteins. -Many researchers feel that answer might be RNA, which is capable of self-polymerization
