Podcast
Questions and Answers
Which gas was conspicuously absent from Earth's early atmosphere?
Which gas was conspicuously absent from Earth's early atmosphere?
- Water vapor (H2O)
- Oxygen (O2) (correct)
- Carbon dioxide (CO2)
- Methane (CH4)
The earliest cells, known as archaebacteria, were eukaryotes.
The earliest cells, known as archaebacteria, were eukaryotes.
False (B)
According to the endosymbiotic theory, what type of bacteria did mitochondria evolve from?
According to the endosymbiotic theory, what type of bacteria did mitochondria evolve from?
alpha-proteobacteria
Lynn Margulis proposed the endosymbiotic theory in the year ______.
Lynn Margulis proposed the endosymbiotic theory in the year ______.
Match the following organelles with their presumed bacterial origins according to the endosymbiotic theory:
Match the following organelles with their presumed bacterial origins according to the endosymbiotic theory:
Which of the following is NOT considered strong evidence for the endosymbiotic theory?
Which of the following is NOT considered strong evidence for the endosymbiotic theory?
The temperature on early Earth was relatively mild, similar to present-day temperatures.
The temperature on early Earth was relatively mild, similar to present-day temperatures.
What are the earliest cells called that appeared approximately 3.5 billion years ago?
What are the earliest cells called that appeared approximately 3.5 billion years ago?
What is the correct order of events in the formation of life?
What is the correct order of events in the formation of life?
The earliest cells were specifically ______ that could survive in extreme environments.
The earliest cells were specifically ______ that could survive in extreme environments.
Flashcards
Early Earth Atmosphere
Early Earth Atmosphere
Early Earth's atmosphere was rich in carbon dioxide, water vapor, methane, ammonia, and hydrogen sulfide, with virtually no oxygen.
Earliest Cells
Earliest Cells
The first cells were prokaryotic archaebacteria, appearing around 3.5 billion years ago, thriving as chemolithotrophs in extreme conditions.
Endosymbiotic Theory
Endosymbiotic Theory
Mitochondria and chloroplasts were once free-living bacteria engulfed by early eukaryotic cells.
Mitochondrial Bacterial Traits
Mitochondrial Bacterial Traits
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Chloroplasts cyanobacteria traits
Chloroplasts cyanobacteria traits
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Life Formation Sequence
Life Formation Sequence
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Order of Organelle Evolution
Order of Organelle Evolution
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Study Notes
- Early Earth's atmosphere was primarily composed of carbon dioxide (CO2), water vapor (H2O), methane (CH4), ammonia (NH3), and hydrogen sulfide (H2S).
- A key characteristic of the early atmosphere was the absence of oxygen (O2).
- Temperatures on early Earth were extremely high, reaching approximately 1000°C.
Earliest Cells
- The earliest cells were prokaryotes known as archaebacteria.
- Archaebacteria appeared around 3.5 billion years ago.
- These early cells were chemolithotrophs, enabling them to thrive in extreme environments.
Endosymbiotic Theory
- Lynn Margulis proposed the endosymbiotic theory in 1967.
Supporting Evidence
- Mitochondrial DNA is circular, resembling bacterial DNA.
- Mitochondria and chloroplasts possess 70S ribosomes, similar to bacteria, unlike the 80S ribosomes in eukaryotes.
- These organelles replicate through binary fission, a method akin to bacterial division.
- Mitochondria evolved from alpha-proteobacteria.
- Chloroplasts evolved from cyanobacteria.
- The nucleus possibly evolved from an archaean.
Sequence of Life Formation Events
- Abiotic synthesis: small organic molecules, such as amino acids and nucleotides, formed.
- Polymerization: these monomers combined to create macromolecules like proteins and RNA.
- Protocells: lipid vesicles encapsulated macromolecules.
- Self-replicating RNA: these molecules further evolved within protocells.
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