Origin of Life

Question 1

Origin of Life

Answer 1

Began 3.5 -3.9 billion years ago

Question 2

Miller-Urey Experiment

Answer 2

Provided evidence that organic molecules needed for life could be formed from inorganic components

Question 3

Steps to Life Formation

Answer 3

Earth and atmosphere formed

Seas formed

Complex molecules synthesized

Polymers and self replicating molecules synthesized

Organic molecules concentrated and isolated into protobionts

Primitive heterotorphic prokaryotes formed

Primitive autotrophic prokaryotes formed

Oxygen and ozone layer formed, abiotic chemical evolution ended

Eukaryotes formed

Question 4

Earth and Atmosphere formed

Answer 4

Atmosphere formed from volcanic outgassing the molten interior of planet earth

Had a reducing atmosphere

Question 5

Reducing Atmosphere

Answer 5

Early earth contained no O2, but it contained CO, CO2, H2, N2, H2O, S, HCl, and HCN

Cyanobacteria responsible for adding oxygen to atmosphere

Question 6

Seas Formed

Answer 6

Earth cooled down, causing gases to condense, resulting in water and minerals that make up the sease

Question 7

Complex Molecules Synthesized

Answer 7

a.a., acetic acid, formaldehyde formed

Monomers formed

Formation of simple molecules made possible by absence of oxygen (oxygen is very reactive)

Question 8

Organic soup

Answer 8

Inorganic molecules made into organic molecules via energy from UV light, lightning, radioactivity, and heat

Question 9

Polymer and Self Replicating Molecules

Answer 9

Monomers formed polymers via dehydration/condensation reaction

Proteinoids formed

Question 10

Protenoids

Answer 10

Abiotic polypeptides formed by allow a.a. to dehydrate on hot, dry substances

Question 11

Protobionts

Answer 11

Self organized sphere of lipids that provided border where chemical reactions could take place (like a cell)

Precursor of cells

Unable to reproduce

Question 12

Microspheres and Coacervates

Answer 12

Abiotically produce protobionts

Question 13

Heterotrophic Prokaryotes

Answer 13

Can’t make own food
Obtain energy by consuming other substances

i.e. Pathogenic bacteria

Organic soup made from inorganic material was the original source of organic material for these heterotrophs

Natural selection occurred over time for competing cells

Question 14

Autotroph

Answer 14

Heterotrophs mutated and gained the ability to make their ow food (from light or energy from inorganic substances)

i.e. Cyanobacteria (photosynthetic bacteria)

Question 15

End of Abiotic Chemical Evolution

Answer 15

Autotrophs release oxygen as a byproduct

Oxygen reacted with UV formed the ozone

Ozone absorbs UV light, preventing it from reaching the surface of the planet
Prevented abiotic synthesis of organic molecules (UV light was the major source of energy)

Question 16

Endosymbiotic Theory

Answer 16

Eukaryotic cells originated from various prokaryotes who, when together, formed a mutually beneficial association. Therefore, mitochondria, chloroplasts, etc. moved inside a prokaryote to form the eukaryote

Question 17

Evidence for Endosymbiotic Theory in Mitochondria/Chloroplasts

Answer 17

Have circular DNA with no proteins like bacteria/cyanobacteria

Ribosomes resemble bacteria and cyanobacteria

Reproduce independently of the eukaryotic cell in a binary fission fashion (like in bacteria)

Double membranes might be from prokaryote surrounding the organelle

Thylakoid membranes similar to photosynthetic membranes in cyanobacteria

Question 18

Evolution of FIsh

Answer 18

Jawless fish—-> cartilaginous fish—-> lobe finned fish

Question 19

Evolution of Chordates

Answer 19

Notochord 
Head 
Vertebral column
Jaw and mineralized skeleton
Lungs/lung derivatives
Lobed fins
Limbs with digits
Amniotic eggs 
Production of milk

Question 20

Notochord

Answer 20

Lanceletes and tunicates

Question 21

Head

Answer 21

Hagfish

Question 22

Vertebral Column

Answer 22

Jawless fish (Class Agnatha)

Question 23

Jaw

Answer 23

Class Chondrichtyes

i.e. sharks

Question 24

Lungs

Answer 24

Ray finned fish

Class Osteichthyes

Question 25

Limbs with digits

Answer 25

Amphibians

Class Amphibia

Question 26

Amniotic eggs

Answer 26

Reptiles (Class Reptilia)

Birds (Class Aves)

Question 27

Production of milk

Answer 27

Mammals (Class Mammalia)