ALL CELLS COME FROM PRE-EXISTING CELLS
•Louis Pasteur made a nutrient broth by boiling water containing yeast and sugar
•Swan-necked flask
Omne vivum ex vivo (All life from life)
•Louis Pasteur made a nutrient broth by boiling water containing yeast and sugar
•Swan-necked flask
Omne vivum ex vivo (All life from life)
Recipe for the Origin of Life
1)The synthesis of simple organic molecules (amino acids) from inorganic molecules (water, carbon dioxide, ammonia)
2)The assembly of these molecules into polymers (e.g. polypeptides from amino acids)
3)Formation of polymers that can self-replicate to allow for inheritance of characteristics
4)Development of membranes with internal chemistry different from their surroundings
1)The synthesis of simple organic molecules (amino acids) from inorganic molecules (water, carbon dioxide, ammonia)
2)The assembly of these molecules into polymers (e.g. polypeptides from amino acids)
3)Formation of polymers that can self-replicate to allow for inheritance of characteristics
4)Development of membranes with internal chemistry different from their surroundings
Prokaryotes to Eukaryotes
Evidence supports the idea that eukaryotic cells are actually the descendents of separate prokaryotic cells that joined together in a symbiotic union. The mitochondrion itself seems to be the ancestor of a free-living bacterium that was engulfed by a bigger prokaryote cell. The host cell benefitted from the ATP the mitochondrion produced, and the mitochondrion benefited from the protection and nutrients surrounding it. This "internal" symbiosis — one organism taking up permanent residence inside another and eventually evolving into a single lineage — is called endosymbiosis.
Evidence supports the idea that eukaryotic cells are actually the descendents of separate prokaryotic cells that joined together in a symbiotic union. The mitochondrion itself seems to be the ancestor of a free-living bacterium that was engulfed by a bigger prokaryote cell. The host cell benefitted from the ATP the mitochondrion produced, and the mitochondrion benefited from the protection and nutrients surrounding it. This "internal" symbiosis — one organism taking up permanent residence inside another and eventually evolving into a single lineage — is called endosymbiosis.
Evidence of this theory:
- Chloroplast and Mitochondria have their own circular DNA molecule like prokaryotes
- Have their own 70s ribosomes (like prokaryotes)
- They can only be produce by pre-existing mitochondria and chloroplast
- Have a double membrane
TOK: Biology is the study of life, yet life is an emergent property. Under what circumstances is a systems approach productive in biology and under what circumstances is a reductionist approach more appropriate? How do scientists decide between competing approaches?
Scientists must have enough system approach to obtain the objective facts. Later, with this data, they can create a reductionist approach. None should be excluded in any circumstance, there should be enough of both to provide data and evidence and express it in different ways (systematic and reductive approaches)
Scientists must have enough system approach to obtain the objective facts. Later, with this data, they can create a reductionist approach. None should be excluded in any circumstance, there should be enough of both to provide data and evidence and express it in different ways (systematic and reductive approaches)