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Chapter 21: The Origin and Evolutionary History of Life 1Learning Objectives 1.

Describe the formation of organic molecules under the conditions believed to have existed on early Earth. This will include: describing examples of reactive surfaces comparing and contrasting the prebiotic soup and iron-sulfur world hypotheses (knowledge/comprehension)

2.

Describe the Miller-Urey experimental model and explain how it could be used to investigate the synthesis of organic molecules. This will include: understanding the prebiotic soup hypothesis, how the experiment was conducted, and the results obtained (knowledge/comprehension/application)

3.

Define the terms anaerobe, aerobe, heterotroph, and autotroph. (knowledge)

4a. Describe the formation of protobionts. Type of micro spear, there can be different kinds. Transgress into coacervates. Spears cannot selfreplicate. Soap bubble- Its gonna separate into two eventually. They don’t have a DNA/RNA division. They are NOT living. Formed spontaneous. Formed when 4 lipids come together making micro spears. If you have a spear, you can have something on the outside and inside, and those enviornments can be different. Isolate outside and inside giving your cells a chance to evolve. 4b. Compare and contrast microspheres and coacervates, which are two types of protobionts. 4c. Describe how protobionts are similar to, as well as different from, eukaryotic cells. (knowledge/comprehension/application) 5. Compare and contrast the major hypotheses related to the evolution of cellular metabolism and regulation. They are the RNA first, DNA first, metabolism first hypotheses, and the DNA/RNA/Protein model. (knowledge/comprehension/application) 6. Describe the transformation in energy conversion when organisms transitioned from an anaerobic to an aerobic environment (knowledge/comprehension) 7a. Compare and contrast how the autogenesis (endomembranous) and serial endosymbiosis theories are related to the evolution of cellular organelles. 7b. Discuss evidence used to support that some organelles arose from an endosymbiotic relationship with eubacteria (knowledge/comprehension/application)

Some key words Autotroph an organism capable of producing its own organic compounds from inorganic materials (photosynthesis for example) Coacervate a specific type of protobiont containing enzymes used for more complex synthesis Endomembranous theory single membrane organelles originated by budding off the internal surface of the plasma membrane Endosymbiont an organism that lives in or on another Endosymbiosis theory double membrane organelles arose from a symbiotic relationship in which the endosymbiont lving inside the cell lost its autonomy and became incorporated as an organelle within that cell Heterotroph an organism not capable of producing its own organic molecules from inorganic materials (will be a consumer) Microsphere one type of protobiont; produced by adding water to abiotically formed polypeptides Protobiont a vesicle of abiotically produced polymers Stromatolite a column of prokaryote cells that become fossilized (living stromatolites are extremely rare)

Chapter 21: The Origin and Evolutionary History of Life Objective 1: Describe the formation of organic molecules under the conditions believed to have existed on early Earth. This will include: describing examples of reactive surfaces comparing and contrasting the prebiotic soup and iron-sulfur world hypotheses (knowledge/comprehension)

No slide I. Environment and evolution of organic molecules Gases present in primitive atmosphere carbon dioxide (CO2) water vapor (H2O) carbon monoxide (CO) nitrogen (N2) ammonia (NH3) [limited] hydrogen sulfide (H2S) methane (CH4) [limited] II. Four requirements for chemical evolution A. Little or no free oxygen so atmosphere was reducing environment B. Energy source was lightning, cosmic and ultraviolet radiation C. Chemical building blocks including water, dissolved inorganic molecules and atmospheric gases were present D. Time Slide 2 I. Formation of organic molecules A. Reactive surfaces 1. Pyrite- Pool of gold. These are too important structures because they are charged structures. Charged surface is going to be attractive. Monomers interactive spontaneously. 2. Clay_____________________________________________________________________ _____________________________________________________________________

Objective 2: Describe the Miller-Urey experimental model and explain how it could be used to investigate the synthesis of organic molecules. This will include: understanding the prebiotic soup hypothesis, how the experiment was conducted, and the results obtained (knowledge/comprehension/application)

Slide 3 B. Prebiotic soup near Earth’s surface- Soup is a mixture. In a prebiotic soup, it’s going to happen in ocean. Different kinds of life forms are found in this area. _______________________________________________________________________ B. Iron-sulfur hypothesis 1. Organic precursors formed near thermal vents] _______________________________ 2. Communities there today_________________________________________________ Slide 4 I. Miller-Urey experiments A. Conditions meant to mimic primitive EarthB. Results All 20 amino acids, bases for RNA and DNA, lipids, ATP, etc. based upon what is in the mixture that is used

Solomon, Berg, Martin, Martin Biology 5th ed.

Objective 3: Define the terms anaerobe, aerobe, heterotroph, autotroph. (knowledge)

Slide 5

I. Terms related to primitive Earth’s environment A. Anaerobic- Conditions in the very very beginning, no oxygen. But then the cyanobacteria came into being and they then liberated oxygen in the atmosphere making it aerobic._______________________________________________________________ B. Aerobe__________________________________________________________________ C. Heterotroph- Rely on autotrophs because heterotrophs cannot convert energy into a form that they can use. Photosynthesis for example, we don’t do it but we can use it from plants to make use of it.______________________________________________________________ D. Autotroph- Auto is self, individual, they are going to synthesize/converting its own energy. ______________________________________________________________ Objective 4 4a. Describe the formation of protobionts. 4b. Compare and contrast microspheres and coacervates, which are two types of protobionts. 4c. Describe how protobionts are similar to, as well as different from, eukaryotic cells. (knowledge/comprehension/application) Presence of oxygen determines what kind of chemical reaction is going to happen. Oxidation or reduction. Think about how cells potential could have become cells in this environment. Slide 6 I. Requirements preceding origin of cells and life A. Abiotic production of nucleotides and amino acids- Synthesis amino acid/RNA. ________________________________________________________________________ B. Polymerization leading to DNA, RNA, and proteins- Monomers spontaneously will polymerize. ________________________________________________________________________ C. Two types of microspheres formed 1. Protobionts- Type of microsphere. It could be a protein, lipid, doesn’t matter. Protobionts transform into coacervates. Coacervates are protobionts, they are a special type of coacerverates. Possibility of being replicate, they do not replicate. Ex: Soap bubble. Protobionts are NOT living, they are formed spontaneously. ____________________________________________________________ 2. Coacervates ____________________________________________________________ D. Membrane enclosed polymers [coacervates] evolved cellular properties 1. Self-replication___________________________________________________________ 2. Inheritance________________________________________________________________ Slide 7 I. Microspheres as Precursors to cells: protobionts and coacervates A. Protobionts 1. What are they? ____________________________________________________________________ 2. Structurally what do they do?

_____________________________________________________________________ Slide 8 3. Functionally what is similar to cells? a. excitability- Electrochemical gradient= Concentration difference. Energy potential. You have an electrical and chemical gradient, If you maintain that gradient/keep it separated, then you have the potential to do some kind of work/ or move those ions/excitability. The difficulty is, there is no DNA yet so there’s not things that you can pass along. Without selfreplication then theres no duplication of the same sphere. _______________________________________________________________ b. osmotically active- Respond to osmotic and chemical changes in environment. ___________________________________________________________________ c. simple chemical reactions ___________________________________________________________________ d. division ___________________________________________________________________

Slide 9 5. What protobionts lack a. DNA- No DNA to establish lineage_______________________________________________________________ b. replication- cant have the duplication of the same spears. They are different.___________________________________________________________

Slide 10 B. Coacervates leading to first cells 1. What are coacervates? Specializied protobiont ( microsphere). Inside the environment, react with molecules. Organic molecules are trapped inside “protected environment”. Glycolysis- you can trap sugar and make it an energy source. Lots of possibilities once you get the enzyme and the substrate inside that sphere. TRAP IT INSIDE AND ITS USEFULL. ___________________________________________________________________ 2. What can they do? ___________________________________________________________________

Brooker Biology pg 460-61

Objective 5: Compare and contrast the major hypotheses related to the evolution of cellular metabolism and regulation. They are the RNA first, DNA first, metabolism first hypotheses, and the DNA/RNA/Protein model. (knowledge/comprehension/application) Slide 11 I. Molecules necessary for cellular metabolism A. Metabolism-first hypothesis – You have to be able to make energy FIRST. You have to have a way to be able to synthesize ATP. Once you have that ATP synthesized, you have to assume that the ATP you are making, provided then the possibility of an energy source for other things to happen. Gotta get the energy, enyzmes before you do anything else. benefits of chemical reactions- Reactions within Coacervates ldea to more functional organization with the sphere A role for coacervates 1. Intrasphere organization _____________________________________________________________________ 2. Energy source ______________________________________________________________________ Slide 12 3. RNA and DNA synthesis- We as people always think of things as we know them. Already know they can form spontaneously on clay. Proteins (enzymes) first would allow organized and directed synthesis of RNA and DNA. DNA prob didn’t come first. RNA most lilkely was synthesized first and DNA second. ______________________________________________________________________ Slide 13

B. RNA-first hypothesis 1. Self-replicating RNA arose first- RNA has enzymatic site. RNA could have replicated

itself. That enzymatic site can then synthesize other things. ____________________________________________________________________ 2. Role for proteins- Came later, Enzyme site in RNA possibly drove the synthesis of other protein structures. ____________________________________________________________________ 3. Information storage- Sequence. RNA could have stored information. RNA could have come first. ____________________________________________________________________

No slide Other supporting factors for RNA 1. Single strand sequence more “easily” replicated 2. Stability of base sequence depends upon environment 3. Can assume a variety of shapes based upon sequence 4. Can get different sequences due to synthesis errors 5. Have been able to synthesize different RNAs in lab

Slide 14 C. DNA involvement in cellular processes 1. Initial DNA synthesis- DNA came from reverse transcriptase. DNA and RNA eventually switched roles- causing today. DNA would have been information storage, and RNA would have taken over synthesis. RNA replicated a duplicate strand. ___________________________________________________________________ ___________________________________________________________________ 2. Positives for evolution of DNA- RNA is single stranded, only have to worry whats on its right and left site, easier to synthesis. DNA is left right and cross direction. DOUBLE STRAND- STRONGER/ stable. DNA is now driving RNA because of its stability. ___________________________________________________________________ Slide 15 4. Negative for DNA synthesis first- No enzymatic properties. It cant really do anything. 5. RANDOM: Captured both RNA and DNA causing self replication. ___________________________________________________________________ No slide

D. Transition from RNA/DNA/protein to DNA/RNA/protein world DNA → RNA → protein Summary DNA became the information storage molecule RNA remained involved in protein synthesis Protein enzymes catalyzed most cell reactions Selection occurred for cells with both DNA and RNA

Slide 16 The first cells were A. Heterotrophs- They would have to rely on the environment. Rely of performed molecules. Consumed spontaneously-formed organic molecules. They were heterotrpoh because they had to rely on the environment. Wouldn’t have the ability to oxygen for ATP synthesis. The early cell structures used fermentation rather than oxygen in the process of making energy. B. Switch from photosyntheisis- eventually organisms obtained energy from other sources volved and suriivid (autotrophs). Mutaations likey responsible for transition. C. Splitting molcules other than water. Perhaps splitting H20rich molecules such as H2S releasing sulfure (easier than splitting water). ______________________________________________________________________ B. Anaerobic environment ______________________________________________________________________ C. Energy source fermentation- Fermentation (anaerobic) ______________________________________________________________________

No slide I. Biological evolution began with the first cells A. Stromatolites 1. Microfossils 2. Minute layers of prokaryotic cells (Cyanobacteria)\ 3. Fossil evidence of early cells 3.5 bya 4. Some still living B. Cyanobacteria These organisms were most likely the source of the first free oxygen in the atmosphere. Splitting of water. Causing electron transport chain. MOST OF THESE ARE THEORIES.

Objective 6: Describe the transformation in energy conversion when organisms transitioned from an anaerobic to an aerobic environment (knowledge/comprehension) Slide 17 II. The transition from heterotroph to autotroph A. Switch from fermentation to photosynthesis ________________________________________________________________________ B. Splitting molecules other than water ________________________________________________________________________ Slide 18 C. Role of cyanobacteria and photosynthesis- Release oxygen in the atmosphere and we can do the electron transport chain. First organisms to obtain H2 by splitting water. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Objective 7: 7a. Compare and contrast how the autogenesis (endomembranous) and serial endosymbiosis theories are related to the evolution of cellular organelles. 7b. Discuss evidence used to support that some organelles arose from an endosymbiotic relationship with eubacteria (knowledge/comprehension/application) Slide 19 Origin of organelles A. Autogenesis [endomembranous] theory- Cell generating by itself. Structures in ER are mostly membrane bound. ____________________________________________________________________________ ____________________________________________________________________________

Slide 20 B. Serial endosymbiosis- You have two different organisms, one is inside or on top of the other. A free living one was capture by the other cell. Eventually it will lose its own indiviaul indentity and stayed in the cell that engulfed it. Chloroplasts and mitochondria.

Origin of organelles Evidence supporting prokaryotic origin of come cellular organelles Comparing mito and chloro to bacteria. Slide 21 A. Size- similar. _______________________________________________________________________ B. Genetic analysis- Mitochondira derived from bacterium similar to moderm alpohaproteiobacteria that syn., ATP via oxidative phos. Membranes and enzyme activity. Similarity between the kinds of activities that proteins associated with the bacterial membrane carry out and activities associated with chloroplasts and mitochondria. Chloroplasts and mitrochondria do replicate. They both simply split. _______________________________________________________________________ C. Enzymes and transport systems- Similar to those in baceterial cells. _______________________________________________________________________

Slide 22 D. Replication- THEY do divide. Binary fission or splitting: similar to bacteria_______________________________________________________________________ E. Antibiotics – Organelle activities harmed by antibiotics effective against bacteria. Antibiotics also affect the enzymatic activities of chloroplasts and bacteria. _______________________________________________________________________...