Chapter 19.7 - Life, it's Origin and early History

Question 1

Where was the oldest fossil on earth found? What is it? How old is it?

Answer 1

Carbon spherule, oldest fossil, 3.86 b.y old - Greenland

Question 2

Origin of life; how did we recreate that?

Answer 2

Experimentally produced bacteria like microspheres

-first they create bacteria like thermal proteins, then the thermal proteins aggregate to form microspheres

Question 3

When did microbial evolution start?

Answer 3

~4 B.y ago

Question 4

Evolution of sexuality of microbes; so what types of sexuality? When did they begin?

Answer 4

Asexual - ~4 B.y

Sexual

Question 5

Types metabolism, and mechanisms

Answer 5

Autotrophic / Chemosynthetic
-Using CO2 + CH4 as C-source (turning inorganic into organcic, using food from raw material, i.e plants using photosynthesis)

Heterotrophic + Organotrophic
(can’t use inorganic material, use food that comes from other organisms)

Photosynthesis (*2.5 B.y ago)
CO2 + H2O –> O2 + CH2O

Respiratory
CH2O + O2 –> CO2 + H2O

Question 6

Define prokaryotes

Answer 6

a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Prokaryotes include the bacteria and cyanobacteria.

Class definition: little kind of cell that has nothing but a strand of DNA in it, and nothing else
-Not extinct, started in Archean,

Question 7

Define eukaryotes. When did they come around?

Answer 7

an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. Eukaryotes include all living organisms other than the eubacteria and archaebacteria.

• EVOLUTIONARY JUMP of eukaryotes as of 1.7 B.y ago
• isn’t just a strand of DNA (prokaryotes), there are other things in there, much more complicated

Question 8

Evolution of microbes; include dates (3 important ones)

Answer 8

Microbial evolution started ~4 B.y ago, with Prokaryotes (Archean)

~1.7 B.y ago with eukaryotes

~1.6 M.y ago - HUMAN MICROBIAL ORIGINS

Question 9

First human evidence?

Answer 9

~1.6 M.y ago; human microbial origins

Question 10

What is the biggest factor of oxygen in the atmosphere?

Where do you find these? What kind of metabolism?

Answer 10

Cyanbacteria

• green slime in river, a prokaryotic cell
• biggest factor of oxygen in atmosphere
• found in stromatolites
• AUTOTROPH

Question 11

What are stromatolites, How long ago did we find them? Where were they?

Answer 11

a calcareous mound built up of layers of lime-secreting cyanobacteria and trapped sediment, found in Precambrian rocks as the earliest known fossils, and still being formed in lagoons in Australasia

class definition:
modern stromatolites
-domo structures that are called stromatolites, they were all over Precambrian
-stromatolites in rocks 3.4 b.y ago in limestone

Question 12

Comment on development of oxygen in the atmosphere. Talk about percentages, dates, reaction, ozone.

Answer 12

No oxygen in atmosphere until 2.5 B.y ago
-rapid spike until then, today has 21%
-photosynthesis is responsible for almost all atmosphere, 99.996% of atmospheric O2
CO2 + H2O –> CH2O + O2
-Water vapour H2O photochemical dissociation contributes to 0.004% of atmospheric O2
-Oxygen (O2) —> Ozone (O3). 90% of ozone in stratosphere (ozone layer).

Question 13

Eukaryotic cells; what consists of them?

Answer 13

Protista - protozoans, algae
Fungi - spores
Plantae - plant tissue cells
Animalia - animal tissue cells

Question 14

How did eukaryotic cells originate? Explain this process

Answer 14

Endosymbiosis - origin of eukaryotic cells

-prokaryote host, establishes a symbiotic relationship, you do this many many times, you get a multi celled organism

Question 15

What is an acritarch

Answer 15

small organic fossil (eukaryotes)

Question 16

Earliest fossils of eukaryotic cells (acritarch’s)?

Answer 16

Proterozoic

• ~60 microns in size
• 1.7B.y ago??

Question 17

Neoproterozoic era

Answer 17

1000 - 541 M.y ago

Question 18

Neoproterozoic life forms

Answer 18

Ediacaran Fauna,
670 - 540 m.y old
-fossils found 
-multicellular life forms
-sexual reproduction
-preserved as molds and casts on undersides of sandstone layers

They were discovered in Australia