Chapter 26

Front 1

stromatolites

Back 1

show evidence of ancient prokaryotic life. banded domes of sedimentary rock that are strikingly similar to layered mats formed today in salt marshes and some warm ocean lagoons by colonies of bacteria and cyanobacteria.

Front 2

history

Back 2

2-3 billion years ago, prokaryotes merged into arachae and bacteria groups

Front 3

oxygen

Back 3

produced by early photosynhthetic prokaryotes=aerobic atmosphere

Front 4

eukaryotic fossils

Back 4

oldest are 1.7 billion years old, but cells probably evolved a hundred millions years earlier. prob evolved from symbiotic communities of proks

Front 5

protists

Back 5

large, disparate group of unicellular eukaryotes and some closely related multicellular organisms.

Front 6

plants, fungi and animals

Back 6

arose during precambrian. plants from green algae, fungi and animals from hetertrophic unicellular organisms. fungi closely related to animals

Front 7

for 90% of earths existence...

Back 7

there was only life in the water

Front 8

symbiotic plant roots and fungi

Back 8

move onto land depended on this association, transformed landscape and created new oppurtunities

Front 9

hypothesis

Back 9

life developed from nonliving materials that became ordered in molecular aggregates that were eventually capable of self replication and metabolism

Front 10

chemical evolution in 4 stages
1

Back 10

1. the abiotic (nonliving) synthesis and accumulation of small organic molecules or monomers such as amino acids and nucleotides

Front 11

chemical evolution in 4 stages
2

Back 11

the joining of these monomers into polymers including proteins and nucleic acids

Front 12

chemical evolution in 4 stages
3

Back 12

the aggregation of abiotically produced molecules into droplets, called protobionts, that had chemcial charecteristics different from their surroundings

Front 13

chemical evolution in 4 stages
4

Back 13

the origin of heredity (which may well have been under way even before the "droplet" stage)

Front 14

earth favored chem. reactions that synthesized organic compounds from inorganic precursors present in the early atmosphere and seas

Back 14

cannot happen in modern world because of oxygen and photosynthetic life. not conducive to spontaneous synthesis of complex molecules because O2 attacks C bonds.

Front 15

gases present in old world

Back 15

volcanoes emit CO, CO2 N2 and water vapor

Front 16

clay

Back 16

substratum for the polymerization reactions prerequisite to life. concentrates amino acids and organic monomers from dilute solutions because the monomers bind to chargedt siteson the clay particles

Front 17

pyrite

Back 17

provides a charged surface and the formation of this mineral from iron and sulfur yields electrons that could support bonding between organic molecules to form more complex products

Front 18

protobionts

Back 18

aggregates of abiotically produced molecules. not capable of precise reproduction but maintain internal chem environment diff from surroundings

Front 19

first DNA molecules

Back 19

first DNa molecules were really short strands of RNA that began self replicating in the prebiotic world

Front 20

ribozymes

Back 20

RNA catalysts that remove introns from Rna and synthesize new RNA

Front 21

RNA evolution

Back 21

in a particular environment, RNA molecules with a certain base sequence are more stable and replicate faster with fewer errors

Front 22

panspermia

Back 22

some organic molecules reached the early earth from space