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Bio 102 Exam 2 Review Notes
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This is a comprehensive and detailed review note on Exam 2 for Bio 102. *Essential Study Material!!
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Energy Sources: microbial and Metabolic DiversityProkaryotic Diversity
-oldest, structurally simplest, and most abundant forms of life
-abundant for over a billion years before eukaryotes
-90 to 99% unknown and undescribed
-ess that 1% cause disease
-fall into 2 domains
-bacteria (also called eubacteria)
-archaea (formerly called archaebacteria)
-many archaeans are extremophiles (live in extreme environments)
→ the morning glory pool, a hot spring in yellowstone national park
Prokaryotes are different that Eukaryotes
-unicellularity
-only eukaryotic cells can be multicellular
-prokaryotes may stuck together to form associations and biofilms
-cell size
-size varies tremendously (generally much smaller than eukaryotes)
-nucleoid
-prokaryotic chromosome is single, circular, double stranded DNA
-found in the nucleoid region of the cell, often have plasmids.
-cell division and genetic recombination
-most divide by binary fission, don’t go through mitosis
-exchange genetic material extensively
-genetic recombination
-occurs through horizontal gene transfer, no sexual reproduction
-not a form of reproduction
-internal compartmentalization
-prokaryotes have no membrane-bounded organelles
-ribosomes differ from eukaryotic cells
-metabolic diversity
-bacteria and archaea are the masters of metabolism
-occupy a broad range of environments=diverse metabolic processes
Requirements of living organisms
-ATP (energy)
-a source of carbon (C-C bonds)
-some additional nutrients
What is so special about O2?
Oxygen is highly electronegative and so is an efficient electron acceptor
,Acquisition of Carbon and energy
Metabolic Diversity
, -Methanogens decompose organic matter when all the other electron acceptors run out
-the microbes that live at hydrothermal vents are examples of extremophiles
Cyanobacteria performed the first photosynthesis
-precambrian cyanobacteria formed mats called stromatolites
The oxygen revolution
-all organisms were small for 3 billion years. Life got big in just 50 million years (1/60th of total
time life had existed)
-cyanobacteria were responsible for changing the earth's atmosphere to one with a high
concentration of oxygen
-no free molecular oxygen existed for the first 2.3 billion years of earth's history
Cyanobacteria and early life
Changed the path of evolution on earth
How did eukaryotes gain the ability to respire (cellular respiration) and produce oxygen (in
photosynthesis)?
Endosymbiosis and the origin of mitochondria
-endosymbiosis theory:
-mitochondria originated when bacterial cells took up residence inside another cell about
2 billion years ago
-symbiosis: individuals of two different species live in physical contact
-endosymbiosis: an organism of one species lives inside the cells of an organism of another
species
-evidences of endosymbiosis theory:
-mitochondria similar size to α-proteobacteria
-mitochondria replicate by fission
-mitochondria have their own ribosomes and manufacture their own proteins
-mitochondria have double membranes
-mitochondria have their own genomes:
-organized as circular molecules
Not all plastids in eukaryotes are derive directly from primary endosymbiosis
Evidences for endosymbiotic origin of chloroplast
-chloroplasts have bacteria like characteristics like mitochondria
-many endosymbiotic cyanobacteria live in eukaryotes today
-chloroplasts have circular DNA with genes similar to those in cyanobacteria
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