Chapter 28, Problem 1ITD

Summary Introduction

To review:

Biologists have long accepted the hypothesis that plastids originate by the endosymbiosis of a cyanobacterium during evolutions. It later forms primary photosynthetic eukaryotes. Until recently, there was no molecular evidence to support this assumption. If the assumption is correct, a phylogenetic tree based on molecular data should support the hypothesis that all primary photosynthetic eukaryotes have a common ancestor.

A group of scientists sequenced the amino acid in 143 proteins encoded by the nuclear genes of primary photosynthetic groups. They later compared the trees to see where the overlap occurred and generated a summary tree. Whether the figure supports or contradicts the hypothesis that a single endosymbiosis event correlated with the evolution of organisms containing plastids is to be discussed.

Introduction:

Symbiosis is also called the endosymbiotic theory. When a eukaryotic organism takes in prokaryotic cell organelles like mitochondria and plastids through endosymbiosis, they evolve and become a part of the host eukaryotic organism. This leads to the formation of plastids, which are believed to have originated from the endosymbiosis of photosynthetic cyanobacteria, later giving rise to primary photosynthetic eukaryotes.