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Questions and Answers
What is a characteristic feature of eukaryotic cells?
What does the last universal common ancestor (LUCA) represent?
How long ago did the last universal common ancestor (LUCA) of living organisms exist?
Which of the following organelles have their own genome?
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What type of enzymes did LUCA possess?
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What is a key characteristic that distinguishes prokaryotic cells from eukaryotic cells?
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Which of the following organelles evolved from symbiotic relationships according to the endosymbiotic theory?
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Which statement about the cellular organization of prokaryotes is correct?
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What does the term 'last universal common ancestor' refer to?
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What is one major difference between prokaryotes and eukaryotes regarding their genetic material?
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What mechanism is suggested to have led to the origin of mitochondria in eukaryotic cells?
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What was the primary function of the ancestral pre-eukaryotic cells before the development of the nucleus?
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Which of the following describes the evolutionary order of organelle development in eukaryotic cells?
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What role do chloroplasts play in the symbiotic relationship with eukaryotic cells?
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What led to the permanent symbiotic relationship between eukaryotic cells and their engulfed bacteria?
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What is a key difference between prokaryotic and eukaryotic cells?
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What process likely occurred as a result of mitochondria's origins in ancestral eukaryotic cells?
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Which of the following statements about the evolution of eukaryotic cells is inaccurate?
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What structure serves as the fundamental unit for both unicellular and multicellular organisms?
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Which process refers to the way in which cells engulf and digest other cells?
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What is a unique characteristic of mitochondria and chloroplasts compared to other organelles?
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Why would a nuclear enclosure be advantageous during phagocytosis?
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Which organisms are classified as eukaryotes based on the content provided?
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What might the predatorial nature of primordial pre-eukaryotic cells have contributed to in eukaryotic evolution?
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What type of cells are considered prokaryotes?
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Which term describes organisms made up of more than one cell?
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Study Notes
Prokaryotes vs. Eukaryotes
- Prokaryotes: lack a nucleus and other membrane-bound organelles
- Eukaryotes: have a nucleus and other membrane-bound organelles, including the nucleus which sequesters the DNA
Domains of Life
- All living organisms belong to one of three domains of life: Bacteria, Archaea, and Eukarya.
Eukaryotic Organelles
- Prokaryotic cell: has the plasma membrane as the only membrane structure, lacks other membrane-bound organelles including the nucleus
- Eukaryotic cell: contains a nucleus, harbors various membrane-bound organelles with distinct functions, contains a cytoskeleton, and has mitochondria and chloroplasts as organelles with their own genome
Last Universal Common Ancestor (LUCA)
- LUCA is the last organism that was a common ancestor to Bacteria, Eukarya, and Archaea.
- Lived around 3.5 billion years ago
- Had enzymes capable of synthesizing lipids for cell membranes and complex metabolic enzymes
- Had ribosomes and could translate proteins
Single vs. Multicellular Organisms
- Single-celled organisms are composed of a single cell that carries out all life functions.
- Multicellular organisms are composed of many cells that work together to carry out life functions.
Plausible Origin of Eukaryotic Cells
- Primordial eukaryotic cells likely originated from predatorial cells that ate other cells through phagocytosis.
- Phagocytosis is the process by which cells eat other cells.
- Many current cells perform phagocytosis, from amoeba to immune cells.
- Phagocytosis requires changes in cell shape driven by cytoskeletal filaments.
Importance of the Nuclear Envelope
- The nucleus evolved as a protective barrier for DNA, preventing its entanglement and breakage during phagocytos
Endosymbiosis Theory
- Mitochondria and chloroplasts are unique organelles that likely originated through endosymbiosis.
- Endosymbiosis is the process by which a larger cell engulfs a smaller cell that doesn't get digested and rather becomes symbiotic.
- The two cells become interdependent and develop a permanent symbiotic relationship often leading to loss of redundant genomes
- Mitochondria originated from the engulfment of oxidizing bacteria.
- Chloroplasts originated from the engulfment of photosynthetic bacteria (cyanobacteria)
The Evolution of Eukaryotic Cells
- Stage 1 (nucleus): Ancestral pre-eukaryotic cells evolved the nucleus to protect DNA molecules from damage.
- Stage 2 (mitochondria): Predation of oxidizing bacteria led to endosymbiosis and the formation of mitochondria.
- Stage 3 (chloroplasts): Some eukaryotic cells with mitochondria engulfed photosynthetic bacteria, which became chloroplasts.
Summary of Key Differences: Prokaryotes vs. Eukaryotes
- Nucleus: Prokaryotes lack a nucleus, while eukaryotes have a nucleus.
- Mitochondria and Chloroplasts: Eukaryotes have mitochondria and/or chloroplasts, prokaryotes do not.
- Other membrane-bound organelles: Eukaryotes have many other membrane-bound organelles, prokaryotes do not.
- Evolution: Both prokaryotes and eukaryotes evolved from a common ancestor.
- Order of Evolution: Nuclear envelope, mitochondria, and chloroplasts evolved in this order.
Other Key Concepts
- Cellular organization: Eukaryotic cells contain many organelles, each with a specific function.
- Cellular energetics: Mitochondria are responsible for ATP production (energy production) within the cell.
- Experimental methods: Studying gene function can be conducted through various experimental methods.
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Description
Explore the fundamental differences between prokaryotic and eukaryotic cells in this quiz. Learn about the domains of life, cell structures, and the significance of the last universal common ancestor (LUCA). Test your understanding of cellular biology concepts.
