MICR-4010 Study Guide - Fall 2018, Comprehensive Midterm Notes - Oxygen, Carbon Dioxide, Bacteria
12 Oct 2018
School
Department
Course
Professor
MICR-4010
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Early Evidence
Earth = ~4.5 to 4.8 bil years old
First evidence of life = ~4.1 bil years ago
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Hadean period: biological life started
First biological compartments = mineral pores
Catalyzed by hydrothermophilic environment
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Source of origin of life
RNA = source
Theory #1: RNA catalytic activity catalyzed its own synthesis
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Theory #2: early viruses evolved from RNA genome cell like
structures
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4 components of life
DNA
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RNA
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Protein
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Membrane
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Early Earth Environment
Anoxic environment: need anaerobic metabolism
Early microbes = chemolithoautotrophy
Inorganic source: hydrogen
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Early electron acceptor: sulfur
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Evolution of organisms assisted by earth becoming oxic
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Extreme environment
High temperature and levels of radiation
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Little to no oxygen
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Deep sea conditions beneficial to help escape these conditions
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Early Microbes
Photoautotrophs: use water to synthesize molecules from carbon dioxide
and use solar energy to oxidize H2S to S
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Chapter 13: Microbial origins and evolution*
Monday, August 27, 2018
4:37 PM
find more resources at oneclass.com
find more resources at oneclass.com
Photoautotrophs: use water to synthesize molecules from carbon dioxide
and use solar energy to oxidize H2S to S
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Stromatolites: fossilized microbial formations
Not actual microbes
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Mineral deposits around where microbes once were
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Cyanobacteria: able to use water to generate oxygen
Cause rise in oxygen to allow energy exploitation
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Phylogeny
Phylogeny: evolutionary history of relation DNA sequences
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Tree of life: based on 16s small subunit rRNA gene
Invented by carl waese
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Established 3 domains: bacteria, archaea and eukarya
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Root = LUCA
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Genomic evidence/theories supporting the 3 domains
60+ genes shared by nearly all cells must have been present in LUCA
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Euk and archaea = similar
Bacteria and archaea diverged before euk existed
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Euk cells = chimeric
Genes from bacteria and archaea
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Translation/transcription material similar to archaea
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Metabolism = bacteria
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Membrane lipids = bacteria (ester link) and archaea (ether link)
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Endosymbiotic hypothesis: chemoorganotrophic bacteria and
cyanobacteria stably incorporated into another cell type to create
mitochondria and chloroplast
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Serial endosymbiosis hypothesis
Euk began as nucleus
1.
Engulf bacterial cell that survive and reproduce
2.
Euk genes reassembling bact genes acquire through gene transfer
Doesn’t account for structurally similar membrane in bacteria
and euk
i.
3.
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Hydrogen hypothesis: euk cell arose from symbiotic relation b/w
bacteria and archaea
Form mitochondria
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Hydrogen producing bacteria are engulfed by hydrogen consuming
archaea
1.
Genes for lipid biosynthesis are transferred from bacterial symbionts
to archaea hosts
2.
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find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Earth = ~4. 5 to 4. 8 bil years old. First evidence of life = ~4. 1 bil years ago. Theory #1: rna catalytic activity catalyzed its own synthesis. Theory #2: early viruses evolved from rna genome cell like structures. Evolution of organisms assisted by earth becoming oxic. Deep sea conditions beneficial to help escape these conditions. Photoautotrophs: use water to synthesize molecules from carbon dioxide and use solar energy to oxidize h2s to s. Cyanobacteria: able to use water to generate oxygen. Cause rise in oxygen to allow energy exploitation. Tree of life: based on 16s small subunit rrna gene. 60+ genes shared by nearly all cells must have been present in luca. Membrane lipids = bacteria (ester link) and archaea (ether link) Endosymbiotic hypothesis: chemoorganotrophic bacteria and cyanobacteria stably incorporated into another cell type to create mitochondria and chloroplast. Euk genes reassembling bact genes acquire through gene transfer i. Doesn"t account for structurally similar membrane in bacteria and euk.
