Chapter 24 Flashcards
What were Earths first organisms and when?
Prokaryotes
Between 3.5-4.0 Billion years ago
How did First living Cells occur?
- abiotic synthesis of small organic molecules such as amino acids and nitrogenous bases.
- Joining molecules into macromolecules such as proteins and nucleic acids
- packaging molecules into photocells (droplets with membranes that maintain own chemistry.
- origin of self replicating molecules that eventually made inheritance possible
What two things are believed to have created an atmosphere for producing organic molecules?
Who’s experiment showed this?
- atmosphere reducing (electron adding)
- High UV radiation
Urey-Miller experiment of abiotic synthesis of simple organic molecules.
What did the Urey-Miller experiment produce?
- 20 amino acids
- ATP
- Sugars
- Lipids
- Purine and pyrimidine bases of RNA and DNA
Proteinoids
Protobionts
Abiotically synthesized polypeptides
Aggregates of abiotically produced molecules able to maintain an internal environment (phospholipid bilayers) and exhibit some life properties
How can you make amino acid polymers
Dripping amino acid monomers onto hot glass, sand, rock or clay
Origin of genetic information
- self replicating requires a genetic mechanism
- RNA may have been first genetic molecule using ribozymes as enzymes
- short polymers of RNA have been formed with zinc (no enzymes)
- RNA is an autocatalytic (acts as an enzyme) to make mRNA, tRNA, rRNA
Major lineages of Life
DOMAIN BACTERIA
DOMAIN ARCHAEA
DOMAIN EUKARYA
How do we know life descended from a common ancestor
All life shares essentially the same genetic code
What two essential processes came out of prokaryotes
Photosynthesis and cellular respiration
Oxygen revolution
Increasing oxygen levels from Cyanobacteria permitted evolution of aerobic life and also created ozone layer
Photoautotrophs
Phtoheterotrophs
Chemoautotrophs
Chemoheterotrophs
- Light for energy, CO2 for carbon
- light for energy, but need complex carbon as carbon source
- can use chemical energy but only need CO2 as carbon
- use chemical energy and need complex carbon sources
Nitrogen fixing
Prokaryotes Can use and metabolize nitrogen in many forms (Can fix atmospheric nitrogen into ammonia which is useable by plants)
Obligate aerobes
Facultative anaerobes
Obligate anaerobes
- need O2 for cellular respiration
- can use O2 of present but will survive without it (fermentation)
- die in O2
Fimbriae
Finer hair like structure on prokaryotes used for attachment
