Major Transitions In Evolution

Question 1

What are the eight transitions?

Answer 1

Replicating molecules-> molecules in compartments

Independent replicators -> chromosomes

RNA as gene and enzyme -> DNA and protein (code)

Prokaryotes -> eukaryotes

Asexual clones -> sexual reproduction

Protists -> multicellularity

Solitary -> colonies

Primitive societies -> human societies with language

Question 2

Why are they major? (6)

Answer 2

1. Focuses on major changes in how info passed between generations
2. Not major phenotype transitions
3. Had to be selected for
4. Increase fitness
5. Differences we see now, may not be first reason that they were favoured
6. Ancestral version hypothesised bs ancestral version still extant.

Question 3

Replicating molecules to molecules in compartments

Answer 3

Origin of cells

Question 4

Independent replicators to chromosomes

Answer 4

Genes

Collection of multiple genes:

• slower to replicate (bad)
• chromosomes selected for (good)
• info is more robust as linked genes have synchronised replication (good)

Prokaryotes are circular and eukaryotes are linear

Caenorhabditis elegans (worm) 
-were complex like this worm

Question 5

RNA as gene and enzyme to dna and protein

Answer 5

Transition from enzymatic replicator
-bad as need to make translocation system

System needs to have single origin

Amino acid have more chemical functions than nucleotides so they’re food cofactors (essential to enzymes).

Question 6

Prokaryotes to eukaryotes

Answer 6

Eukaryotes:
Cytoskeleton maintains shape
Internal membranes
Linear chromosomes in nucleus

Prokaryotes:
Ridged cell walls
No internal membranes
Single circular chromosome