Evolution- 4.1 Origin of Life

Question 1

Describe the possible uses of RNA in the first simple cells

Answer 1

Cells used it to store genetic information and it allowed the replication of genetic information in its base sequence which it used to pass on genetic information to daughter cells through complementary base pairing.

Question 2

Describe the possible roles of ribozymes in the first simple cells

Answer 2

possibly found in the cytoplasm, acted as enzymes and catalysed reactions in primitive cells.

Question 3

Using fossil evidence describe the evidence that prokaryotic cells existed before eukaryotic cells

Answer 3

The oldest known prokaryotic fossils are around 3.5 billion years old while the oldest eukaryotic fossils are 1.5 billion years old.
Eukaryotic and Prokaryotic cells both have ribosomes and a cell membrane.

Question 4

Explain how the ancestry of most existing eukaryotic cells probably involved endosymbiotic events. (Any is fine, 2 is probable easiest answer)

Answer 4

1. Structural: Mitochondria and Chloroplasts within eukaryotic cells have a double membrane, where the internal membrane is similar to that of prokaryotic cells while the external membrane is similar to that of eukaryotic cells. These similarities suggest smaller prokaryotic cells was engulfed by larger prokaryotic cell.
2. Structural: Also, Mitochondria and Chloroplasts have circular DNA, like prokaryotic cells.
3. Structural: Also, Mitochondria and Chloroplasts have their own protein synthesis systems as they contain ribosomes that are similar to the structure of prokaryotic ribosomes.
4. Functional: Also, Mitochondria and Chloroplasts are self-replicating and divide by binary fission, like prokaryotic cells, indicating they could have lived independently.