1.5: Origin of Cells

Question 1

1.5.U1 Discuss two implications of all cells being formed from pre-existing cells.

Answer 1

There must have been an original cell.

All cells are related (if even distantly)

Question 2

1.5.U2 Outline the 4 processes needed for the spontaneous origin of cells on Earth.

Answer 2

1. The synthesis of simple organic molecules from inorganic compounds
2. The assembly of these organic molecules into polymers
3. Packaging of molecules into membranes with an internal chemistry different from the surroundings
4. The formation of a polymer that can self-replicate

Question 3

1.5.U2 Outline the experiments of Miller and Urey into the origin of organic compounds.

Answer 3

Miller and Urey created a model of early Earth’s hypothesized conditions. Their conclusion was that organic molecules can form under the hypothesized conditions of early Earth.

Question 4

1.5.U2 Define polymerization, monomer and polymer.

Answer 4

Polymerization - A chemical reaction in which two or more molecules (monomers) combine to form larger molecules (polymers)

Monomer - “one part”, the single building block unit of a polymer

Polymer - “many parts” A large molecule composed of many monomer subunits

Question 5

1.5.U2 Outline two properties of RNA that would have allowed it to play a role in the origin of life

Answer 5

​

1. RNA can self-replicate
2. RNA can act as a catalyst

Question 6

1.5.U3 State the endosymbiotic theory

Answer 6

Theory that states that mitochondria and chloroplasts evolved from free-living prokaryotic cells that were engulfed (not digested) by early eukaryotic cells. The mitochondria and chloroplasts evolved as symbiotic parts of these cells.