Symbiogenesis - Wikipedia
The endosymbiotic theory, which holds that eukaryotic mitochondria and from unicellular algae that live in a symbiotic relationship with their. Structure and function of mitochondria and chloroplasts. Symbiosis is a relationship in which organisms from two separate species live in a close, dependent. I. A theory on the Origins of Eukaryotic Cells: Mitochondria and Chloroplasts mutually benefiting functions from their symbiotic relationship.
Over millions of years of evolution, mitochondria and chloroplasts have become more specialized and today they cannot live outside the cell.
Origin of mitochondria - endosymbiosis theory
It's Just a Theory In everyday speech, people use the word theory to mean an opinion or speculation not necessarily based on facts. But in the field of science, a theory is a well established explanation based on extensive experimentation and observation. Scientific theories are developed and verified by the scientific community and are generally accepted as fact.
And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host.
The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division. It is passed down directly from mother to child, and it accumulates changes much more slowly than other types of DNA.
Because of its unique characteristics, mtDNA has provided important clues about evolutionary history. For example, differences in mtDNA are examined to estimate how closely related one species is to another. Analysis of mitochondrial DNA from people around the world has revealed many clues about ancient human migration patterns.
Models for Astrobiology Archaea survive today in extremely harsh environments, such as evaporative salt ponds on the edge of Great Salt Lake above and the boiling hot springs of Yellowstone National Park right.
Mitochondria and chloroplasts
Conditions on Earth 4 billion years ago were very different than they are today. The atmosphere lacked oxygen, and an ozone layer did not yet protect Earth from harmful radiation.
Heavy rains, lightning and volcanic activity were common. Yet the earliest cells originated in this extreme environment.
They contain their own DNA, which is circular as is true with bacteria, along with their own transcriptional and translational machinery.
Mitochondrial ribosomes and transfer RNA molecules are similar to those of bacteria, as are components of their membrane. These and related observations led Dr. Lynn Margulis, in the s, to propose an extracellular origin for mitochondria.
Some species of present day protists contain living organisms within their cytoplasm. For example, Paramecium bursaria are hosts for zoochlorellae, photosynthetic protists, that reside within the cytoplasm.
Mitochondria and chloroplasts (article) | Khan Academy
The relationship appears to be symbiotic. The endosymbiont gains protection and possibly some essential nutrients from the host cytoplasm. The host has a readily available food source when its usual food source is depleted. If you have the opportunity to observe P. They are residents within the cytoplasm itself, and either are descended from organisms that survived endocytosis or have some mechanism for escaping food vacuoles once they are ingested.