Chapter 26 Reading Quiz According to your book, how long ago did life probably originate on Earth? What were probably the first types of life? What was probably the first genetic material? Why do I keep phrasing the questions using “probably”? List the three Domains.

1. Provide at least two lines of evidence for the antiquity of life. The fossil record - although there is no fossil record for the very beginning - stromatolites  banded domes of sediment similar to the layered mats constructed by colonies of cyanobacteria and bacteria Contemporary organisms - in their molecules and anatomy they can carry traces of evolutionary history 

2. Describe the contributions that Oparin, Haldane, Miller, and Urey made towards developing a model for abiotic synthesis of organic molecules. Oparin & Haldane  postulated that the reducing atmosphere and greater UV radiation on primitive earth favored reactions that built complex organic molecules from simple monomers as building blocks Miller & Urey  tested O & H’s hypothesis by simulating the conditions on early earth by constructing an apparatus containing H2O, H2, CH4, and NH3 (stimulated by “lightning”) - produced some amino acids and other organic molecules 

Laboratory simulations have produced organic polymers 3. Provide plausible evidence to support the hypothesis that chemical evolution resulting in life’s origin occurred in four stages: a. abiotic synthesis of organic monomers b. abiotic synthesis of polymers c. formation of protobionts d. origin of genetic information Laboratory simulations have produced organic polymers - had to happen without enzymes - clay may have been the substrate for abiotic synthesis as monomers bind to charged sites, concentrating amino acids - metal ions could catalyze the dehydration reactions to bring monomers together continued……

continued…… #3 continued… Protobionts  aggregates of abiotically produced molecules able to maintain an internal environment different from their surroundings and exhibiting some life (metabolism & excitability) - spontaneous formation of protobionts: when mixed with cool water, proteinoids self-assemble into microspheres surrounded by a selectively permeable membrane continued……

The end of #3… RNA was probably the first genetic material - a primitive mechanism for aligning amino acids along RNA molecules were probably the first genes - evidence: RNA molecules may have been able to self-replicate - RNA is autocatalytic (as indicated by “ribozymes”) 

4. Describe the basis for Whittaker’s five-kingdom system. The 2 – kingdom system (plants & animals) was no longer suitable as biologists learned more about the structures and life histories of different organisms 1. Monera 2. Protista 3. Plantae 4. Fungi 5. Animalia 

Archaebacteria Eubacteria Protista Fungi Plantae Animalia  5. Describe three alternatives to the five-kingdom system and explain the rationale for each. Six – kingdom - prokaryotes are split based on molecular evidence from an early evolutionary divergence Archaebacteria Eubacteria Protista Fungi Plantae Animalia 

Bacteria Archaea Eukarya  #5 continued…… Three – domain more significance is given to the split between eu- & archae- bacteria by using the superkingdom taxon “domain” Eukarya includes the four kingdoms of the eukaryotes Bacteria Archaea Eukarya 

The end of #5… 3. Eight kingdom - separates the prokaryotes and the types of protists Bacteria Archaea Archaezoa Chromista Protista Fungi Plantae Animalia  the end!!