Origin of Life

Question 1

Chemical Composition of Earth’s Early (Archaen) Atmosphere

Answer 1

no free molecular oxygen in ocean atmosphere

Question 2

Miller and Urey Experiments

Answer 2

1953;

• demonstrated that basic blocks of life (amino acids) can be synthesized from inorganic molecules
• amino acids, the basic building blocks of protein, are common place in our solar system

Question 3

Significance of Murchison Meteorite

Answer 3

contained all 20 amino acids

Question 4

Compound Synthesis (Molecules to Microbes)

Answer 4

abundant organic compounds found in the universe are concentrated and synthesized on earth (on clay materials)

Question 5

Phospholipid Bilayer (Molecules to Microbes)

Answer 5

cell membranes (made up of fatty acids and alcohol)

• bilayers allow molecules to enter and exit do to their fluidity

Question 6

Replication (Molecules to Microbes)

Answer 6

fatty acid membranes likely occurred independently at first;

Question 7

Putting Them Together (Molecules to Microbes)

Answer 7

• simple organic compounds firm and eventually polymerize
• self replication molecules (RNA) occur
• self replicating machinery gets enclosed in a membrane
• true cells with RNA arise
• modern DNA replaces RNA

Question 8

Role of Mineral Surfaces (Clay) in Concentrating and Organizing Organic Molecules

Answer 8

large surface area which serve as a template for organizing simple molecules in to more complicated molecules

Question 9

Early RNA World as a Precursor to the Modern DNA World

Answer 9

• RNA Molecules are capable of catalyzing chemical reactions
• RNA in ribosomes (Ribozymes) catalyze their own self replication with out enzymatic mediators
• RNA plays a key part in expression of DNA indicating that RNA was a key agent in the catalysis and genetic coding in prebiotic world
• Protein may have been recruited to assist RNA replication then other metabolic processes
• finally may have enclosed in a membrane

Question 10

Hyperthermophile

Answer 10

organisms that live in extremely hot temperatures

Question 11

Deep-Sea Hydrothermal Vents

Answer 11

likely candidate for where life began!

Question 12

Green Sulfur Bacteria

Answer 12

found living around deep-sea hydrothermal vents

Question 13

Archean-Aged Terranes of Pilbara Craton, Australia

Answer 13

oldest, non-metamorphasized sedimentary rocks

Question 14

Stromatolites

Answer 14

3.5 billion years old;

oldest fossils on Earth (not with actual organisms but were once mats of bacteria)

Question 15

Cyanobacteria

Answer 15

what forms stromatolites;

formed by the filamentous cyanobacteria (prokaryotes) that do oxygenic photosynthesis (doesn’t produce any oxygen though)

Question 16

Oldest Eukaryote Fossils

Answer 16

time is hard to pinpoint due to poor preservation and one’s concept of what fossils of eukaryotes look like

Question 17

Arcitarchs

Answer 17

2 Ga;

primitive forms of marine algae, single celled eukaryotes

Question 18

3 Pieces of evidence implicating the early Evolution of Eukaryotes (endosymbiosis)

Answer 18

1. ) size of organelles within eukaryotic cells is nearly identical to the size of few living prokaryotes to which they are metabolically similar
2. ) mitochondria and chloroplasts have their own cell membranes just like prokaryotes do
3. ) organelles have their own DNA, RNA, and Ribosomes (ssRNA sequences are similar to bacteria)

Question 19

Evidence of fusion of Archaea and Bacteria in the evolution of Eukaryotes

Answer 19

• organelles have their own DNA, RNA, and Ribosomes; ssRNA sequences similar to bacteria
• proteins used by DNA to package their DNA in chromosomes, to transcribe DNA and to decode genetic messages remarkably similar in Eukaryotes
• based on ssRNA sequences, archaea are most similar to eukaryotes than bacteria

Question 20

When did concentration of free molecular oxygen first start to rise?

Answer 20

“The Great Oxygenation Event”

• around 2.5-2.3 Ma
• due to oxygenic photosynthesis by cyanobacteria

Question 21

What is the Ediacara Fauna?

Answer 21

soft bodied fossils preserved as impressions;

first multicellular animals

570 Ma (pre-Cambrian Period)

Question 22

How old are the fossil embryos in the Doushantuo formation of China?

Answer 22

635 - 571 Ma