Endosymbiotic Theory (1.5) Flashcards
What cell theory statement relates to the origin of the cell?
Every cell comes from preexisting cell, no cells spontaneously generated.
Discuss implications of all cells being formed from preexisting cells.
1 all cells can be traced back to the fertilization of the sperm with the egg, AKA zygote.
What questions the third implication?
How life originated and how the first cell came into being are matters of speculation, since these events cannot be reproduced in the laboratory. Nonetheless, there are several studies that provide evidence for the first cell appearance.
Outline the four processes needed for the spontaneous origin of cells on Earth.
- The synthesis of simple organic molecules from inorganic compounds (formation of biological MONOMERS: amino acids, nitrogenous bases, fatty acids and simple sugars).
- The assembly of these organic molecules into polymers (formation of biological POLYMERS via anabolic reactions creates polysaccharides, proteins, and RNA strands).
- The formation of a polymer that can self replicate, enabling inheritance. (formation of a nucleic acid polymer (likely RNA) that can encode hereditary information).
- Packaging of molecules into membranes with an internal chemistry different from the surroundings (formation of protocells that carry out metabolic reactions within an enclosed system.).
What is the Miller and Urey experiment?
The Miller-Urey experiment was a simulation of conditions on the early Earth testing the idea that life, or more specifically organic molecules, could have formed by nothing more than simple chemical reactions.
How did Miller and Uray replicate the conditions of earth back then?
The experiment used an apparatus consisting of:
- Boiled water evaporates and moves into the larger flask, where it combines with ….
- … methane, ammonia and hydrogen gases in a large flask. Sparks are fired between electrodes to simulate lightning.
- A cooling condenser turns steam back into liquid water, which drips down…
- ….into the trap, where organic molecules produced in the reactions also settle.
What did Miller and Uray conclude with their experiment?
Organic molecules, including amino acids, can form from inorganic compounds*
Organic molecules could have formed on prebiotic Earth.
The Miller and Uray experiment proved what process needed for the spontaneous origin of cells on Earth?
The first one: the synthesis of simple organic molecules from inorganic compounds (formation of biological MONOMERS: amino acids, nitrogenous bases, fatty acids and simple sugars).
How can we explain the origin of the first eukaryote cell?
Endosymbiotic theory
Explain the Endosymbiotic theory?
States that mitochondria and chloroplasts evolved from free-living prokaryote cells that were engulfed (but not digested) by early eukaryotic cells. The mitochondria and chloroplasts evolved as “symbiotic” ( = together with, both benefitting) “endo” ( = inside living).
Outline the major events of the Endosymbiotic theory?
An ancestral prokaryote infolds its cell membrane, which leads to a cell with a nucleus and endomembrane; it engulfs an aerobic prokaryote (mitochondria) and this has its compartmentalization (animal cell).
Later on, a similar cell engulfs a photosynthetic prokaryote leading to a plant cell.
What are the evidences for the endosymbiotic theory?
Mitochondria and Chloroplasts have similar traits, such as:
shape; size; 70s ribosomes; circular, naked DNA; gene sequences; movement; binary fission; antibiotic inhibition; double membrane (one from the original ancestral prokaryote, and another from the early eukaryote).
