1 5 Origin of Cells Spontaneous Generation Belief

1. 5 Origin of Cells

Spontaneous Generation • Belief that living matter could arise from non living matter. • Was believed up until the 1700’s.

Louis Pasteur • Disproved theory of spontaneous generations. • Used swan neck flask to prove bacteria, fungi, and spores do not spontaneously generate.

Life is An Emergent Property • Unicellular and multicellular life arose from non living matter. • Took many years, so not spontaneous. • Experiments have led to an understanding of how this may have happened.

1. Producing Sugars and Amino Acids • Miller and Urey passed steam through ammonia and methane. • Used electrical impulses to simulate lightning. • Amino acids and other carbon compounds were created.

• 1 st carbon compounds may have been created around deep sea vents.

2. Formation of Membranes • If phospholipids were among 1 st compounds created, they would have formed bilayers naturally.

3. Genetic Inheritance • DNA could not be the first genetic material. • RNA could have been first genetic material as it is self replicating and acts as an enzyme.

Endosymbiotic Theory • Explains how mitochondria and chloroplasts appeared in eukaryotic cells.

• What are now mitochondria were taken in by larger anaerobic prokaryotes. • The smaller mitochondria grew with the cell. • When large cell divides, so did the mitochondria.

• The larger cell would provide food for the smaller cell, and the smaller cell could carry out aerobic respiration providing energy for the large cell.

Evidence For Endosymbiotic Theory • Both chloroplasts and mitochondria have their own DNA. • They both also contain 70 s ribosomes, like prokaryotic cells.