Biology Test 1- Lec 1 Flashcards
enzyme
highly selective catalysts
molecules that trigger, catalyze, and guide specific metabolic pathways
geometry - specific 3 dimensional structure
nucleic acids
polymer made of nucleotides (RNA and DNA)
nucleotides
monomers that create nucleic acids
protobiont
aggregates of abioticaly produced compounds
CAN: maintain internal environment, metabolize, and reproduce
CANNOT: respond to environment, grow and develop, no biological evolution
reducing atmoshpere
no atmosphere, initial atmospheric conditions
relevance: O2 is not conducive to spontaneous development of complex molecules
What chemical were used in Miller-Urey?
H2O, CH4, NH3, H2
What chemicals were produced in Miller-Urey?
17 of 20 amino acids, purines, pyrimidines, all 5 base pairs of DNA and RNA, 3 & 6 carbon sugar
Did not include 5 carbon sugars
What errors existed in Miller Urey and how was this later refined?
Volcanic gases: CO, CO2, H2S, SO2, N2, and even trace amounts of O2
more diverse molecules: Vit B6, pantothenic acid, fatty acids (aka: membranes), ribose
When these gases were added to experiment, even more diverse molecules.
Describe layout of Miller-Urey
Enclosed glass tubes heated water chamber -evaporation gas chamber (H20, CH4, NH3, H2_, spark to simulate lightning condenser collecting tube
panspermia
life has extra-terrestrial origin, life arrive on asteroids, meteroids, etc.
Four Stages of Chemical Evolution
Chemical Evolution
Stage 1: Spontaneous formation of organic molecules (above)
Stage 2: Monomers > Polymers (polymerization)>Enzymes
Stage 3: Isolation by membranes
Stage 4: Protobiont
Requirements of Chemical Evolution
Catalysts:
Clay = scaffolding
Nickel and Iron - thermal vents
Evolution can’t occur in simple aqueous soln, beacuse polymerization competes w/ hydrolysis
Describe the Candidates for First Enzyme and which is most likely
requirements: information storage, assume a variety of 3D structures, enzymatic/replication properties, ability to reproduce itself, small tendency toward mutation (evolution)
DNA: cannot calalyze reaction independently, set geometry (double-helix), stable and relatively low rate of mutation, (though good info storage)
Protein: many different shapes, enzymatic/catalytic, but there is no known way for proteins to replicate themselves “faithfully.” They are also less prone to mutation than nucleotides.
RNA: info storage, different 3D structures, enzymatic activity , and also prone to mutation (evolution)
What makes RNA enzymatic and less stable?
ribose which is a ribozyme
and highly reactive OH group
what is a ribozyme
ribonucleic acid enzyme , as opposed to a protein enzyme
