Campbell: Early Earth And The Origin Of Life

Front 1

What is the range of dates for the origin of life?

Back 1

3.5 to 4.0 billion years ago

Front 2

Where were the oldest fossils found?

Back 2

western Australia

Front 3

What type of life dominated between 3.5 and 2.0 billion years ago?

Back 3

prokaryotes

Front 4

In what form are most early prokaryote fossils found?

Back 4

in stromatolites, mats of fossilized microbes

Front 5

When did cyanobacteria evolve?

Back 5

>2.7 billion years ago

Front 6

Where did the first oxygen go?

Back 6

It dissolved into the ocean and seas until it became saturated, and also oxidized iron in the water to iron oxides.

Front 7

Besides stromatolites, where else have early fossils been found?

Back 7

near hydrothermal vents

Front 8

When did atmospheric oxygen concentrations increase the most?

Back 8

around 2.2 billion years ago

Front 9

What caused the second increase in O2 in the atmosphere?

Back 9

the development of eukaryotes with chloroplasts

Front 10

When did eukaryotes first appear?

Back 10

between 2.1 and 2.7 billion years ago

Front 11

What are endosymbionts?

Back 11

symbiotic cells w/in the larger host cell, like mitochondria and chloroplasts

Front 12

When did multicellular eukaryotes arise?

Back 12

molecular clocks say 1.5 billion years ago, but the earliest found are 1.2

Front 13

When is the snowball earth hypothesized to have been?

Back 13

750-570 million years ago

Front 14

When did the major animal phyla appear?

Back 14

~543 million years ago

Front 15

What two animal phyla evolved first?

Back 15

cnidarians (jellies) and poriferans (sponges)

Front 16

When was the land colonized?

Back 16

around 500 million years ago

Front 17

Which two groups landed first?

Back 17

plants and fungi (near their roots)

Front 18

Order these: mammals, fishes, birds, reptiles, amphibians.

Back 18

fishes -> amphibians -> reptiles -> birds and mammals

Front 19

Pasteur's principle of life from life is called what?

Back 19

biogenesis

Front 20

What are the four stages of the origin of life?

Back 20

1) small organic molecules, 2) polymerization, 3) self-replication, 4) packaging into protobionts w/membranes

Front 21

Why can't life arise today?

Back 21

Oxygen in the atmosphere prevents macromolecules from forming.

Front 22

Who first hypothesized the origin of life scenario?

Back 22

Oparin and Haldane

Front 23

What gases were in the Miller-Urey flask?

Back 23

water, hydrogen, methane, ammonia

Front 24

What differences are there between the Miller-Urey atmosphere and the early atmosphere hypothesized today?

Back 24

carbon monoxide, carbon dioxide, nitrogen, and some oxygen also there, no hydrogen left

Front 25

Other than the sea-atmosphere boundary, where have small organic molecules been hypothesized to arise?

Back 25

deep-sea hydrothermal vents and outer space

Front 26

Where were polymers first formed?

Back 26

hot rocks would have vaporized the water, concentrated the monomers, and caused them to polymerize

Front 27

What was likely the first genetic material?

Back 27

RNA

Front 28

Which came first, genes or enzymes?

Back 28

RNA served as both.

Front 29

What are ribozymes and what do they do?

Back 29

RNA catalysts that remove introns from RNA and catalyze RNA (r, t, m) synthesis

Front 30

How would natural selection work in an RNA world?

Back 30

RNA molecules would compete for monomers, and those that are more stable would outcompete others and grow.

Front 31

What are protobionts?

Back 31

aggregates of abiotically produced molecules that maintain a different chemical environment inside than outside and metabolize for energy

Front 32

What are similar to protobionts?

Back 32

Liposomes, when lipids form a bilayer like cell membranes

Front 33

Why did DNA take over for RNA?

Back 33

DNA is much more stable than RNA.

Front 34

Who invented the five-kingdom system when?

Back 34

Robert Whittaker of Cornell in 1969

Front 35

What are the five kingdoms?

Back 35

Monera, Protista, Plantae, Fungi and Animalia

Front 36

How did Whittaker define the kingdoms?

Back 36

Plants are photosynthetic autotrophs, fungi are absorptive heterotrophs, animals are digestive heterotrophs, protists are all other eukaryotes and Monera are prokaryotes.

Front 37

What are the three domains?

Back 37

Bacteria, Archaea, and Eukarya

Front 38

How do the five kingdoms and three domains fit into each other?

Back 38

Bacteria and Archaea are within Monera, while Eukarya consists of the other four kingdoms.