Unit 5 - Ch 21 - Origin Of Life

Question 1

Four theories of the origin of life

Answer 1

1. Intelligent design
2. Naturalistic
3. Theistic naturalism
4. Cosmozoic

Question 2

Intelligent design

Answer 2

Some features of life are best explained by an intelligent cause instead of purely materialistic causes. This theory does not identify the cause agent. Some supporting scientists include: Behe, Minnich, Wells and Dembski.

Question 3

Irreducible complexity

Answer 3

This is considered evidence for Intelligent Design. Structures with multiple components that only function as a whole are irreducibly complex.
=> bacterial flagellum

Question 4

Design inference

Answer 4

From irreducibly complex structures, design is inferred.

Question 5

Naturalistic

Answer 5

Life arose on earth by purely natural processes about 3.5 BYA.

Question 6

Theistic naturalism

Answer 6

Life originated by divine intervention and natural processes produced the diversity. A compromise between creationism and naturalism.

Question 7

Cosmozoic

Answer 7

Popular in the 1800’s and resurrected currently as Panspermia
Life on earth came from outer space. Evidence includes meteorites with organic residues. Crick and Pauling are scientists who support this theory.

Question 8

Hypothetical Conditions For Naturalistic Origin of Life (6)

Answer 8

1. Energy source
2. Appropriate chemicals
3. Absence of O2
4. Time
5. Aqueous environment
6. Chemical selection

Question 9

Explain why an “energy source” is a hypothetical condition for the naturalistic theory

Answer 9

Necessary to bring about change. Sunlight, geothermal, radiation, lightning.

Question 10

Explain why “appropriate chemicals” are a hypothetical condition for the naturalistic theory

Answer 10

Water, inorganic ions and organics. Hydrogen rich conditions, like in our solar system, colide to create new molecules.

Question 11

Explain why the “absence of O2” is a hypothetical condition for the naturalistic theory

Answer 11

No oxidation; organics break down unter O2.

Question 12

Explain why “time” is a hypothetical condition for the naturalistic theory

Answer 12

Long time periods are required for extremely low probability events. Eons. From the time earth formed to the time life originated is roughly 1 billion years.

Question 13

Explain why an “aqueous environment” is a hypothetical condition for the naturalistic theory

Answer 13

Temperature stable due to water’s high specific heat. Water is a source of dissolved materials, protects from UV, and encourages mixing.

Question 14

Explain why “chemical selection” is a hypothetical condition for the naturalistic theory

Answer 14

Selection for abiotic systems. Selecting for chemicals with longevity and / or stability.

Question 15

Hypothetical Steps in Naturalistic Origin (10)

Answer 15

1. Organic monomers
2. Formation of polymers
3. Form aggregates
4. Simple metabolism
5. Heredity information
6. First true organisms (prokaryotic)
7. Photosynthesis
8. Aerobic respiration
9. Origin of eukaryotes
10. Evolutionary tree

Question 16

Hypothetical Steps in Naturalistic Origin:

Organic monomers

Answer 16

First Step

Miller and Urey test the Oparin and Haldore Hypothesis by simulating the hydrologic cycle (atmosphere and ocean). They filled the atmosphere with H rich compounds (reducing atmosphere). Nucleotides and amino acids will form.
Problems: living organisms only use L forms of AA’s but D and L are formed. Geochemists don’t think the early atomshpere was reducing.

Question 17

Hypothetical Steps in Naturalistic Origin:

Formation of polymers

Answer 17

Second step

From monomers via condensation reactions. Endergonic.
Hydrolitic activity is favored.

Question 18

Hypothetical Steps in Naturalistic Origin:

Form aggregates

Answer 18

Third step

The compartmentalization of polymers. Analagous to cells. Coaccervates (old) vs. proteinoid microspheres (newer). Compartments favor polymerization of monomers (concentrating reactants).

Question 19

Hypothetical Steps in Naturalistic Origin:

Simple metabolism

Answer 19

Fourth step

Simple chemical reactions occur faster in aggregates because of the concentration gradient of reactants.

Question 20

Hypothetical Steps in Naturalistic Origin:

Heredity information

Answer 20

Fifth step

Needed for precise reproduction. It is believed that RNA came first, then Protein, then DNA

Question 21

Hypothetical Steps in Naturalistic Origin:

First true organisms

Answer 21

Sixth step

prokaryotic
About 3.5 BYA, probably heterotrophs, probably anaerobes.

Question 22

Hypothetical Steps in Naturalistic Origin:

Photosynthesis

Answer 22

Seventh step

The first forms of life may have used H2S as an e- source. Cyanobacteria use water as e- source. Oxygen levels likely increased over time, ozone over time, creating proctective UV layer. Then terrestrial environments may have become available. Probably prokaryotic.

Question 23

Hypothetical Steps in Naturalistic Origin:

Aerobic respiration

Answer 23

Eighth step

Organisms can take advantage of increasing O2 levels and become more efficient at ATP produciton. Still probably prokaryotic. Q: Where did the ATP come from required for glycolysis?

Question 24

Hypothetical Steps in Naturalistic Origin:

Origin of eukaryotes

Answer 24

Ninth step

Endosymbiotic Theory - Chloroplasts and mitochondria may have been free-living organisms at one time. This is suggested because the both contain DNA and ribosomes. It is believed that they parasitized host cells to form eukaryotes.

Question 25

Hypothetical Steps in Naturalistic Origin:

Evolutionary tree

Answer 25

Tenth step

Divergent evolution producing the various life forms.