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Related Concept Videos

Animal Mitochondrial Genetics02:59

Animal Mitochondrial Genetics

Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
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Mitochondrial Membranes

A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...
Mitochondrial Membranes01:45

Mitochondrial Membranes

A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...
Mitochondrial Precursor Proteins01:39

Mitochondrial Precursor Proteins

Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70  chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Evolution of New Traits in Microbes01:24

Evolution of New Traits in Microbes

Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
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Mitochondria

Mitochondria are eukaryotic cellular organelles that are known to produce energy through a process called oxidative phosphorylation. Besides their primary function, mitochondria are involved in various cellular processes, including cell growth, differentiation, signaling, metabolism, and senescence. Age-related changes cause a decline in mitochondrial quality and integrity due to increased mitochondrial mutations and oxidative damage. Thus, aging can severely impact mitochondrial functions,...

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Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models
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Mitochondrial evolution.

Michael W Gray1

  • 1Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3M 4R2, Canada. m.w.gray@dal.ca

Cold Spring Harbor Perspectives in Biology
|September 7, 2012
PubMed
Summary
This summary is machine-generated.

Mitochondria, originating from Alphaproteobacteria, are viewed as a mosaic organelle. New data challenge the classical endosymbiont hypothesis, questioning if mitochondria arose with or after the eukaryotic cell.

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Area of Science:

  • * Evolutionary biology
  • * Molecular biology
  • * Cell biology

Background:

  • * Mitochondria possess bacterial ancestry, originating from Alphaproteobacteria.
  • * The endosymbiont hypothesis posits mitochondria evolved via symbiosis with a eukaryotic host.
  • * Mitochondrial genome evolution is diverse, with many proteins originating outside Alphaproteobacteria.

Purpose of the Study:

  • * To re-evaluate the evolutionary origins of mitochondria in light of new data.
  • * To explore the implications of mitochondrial genetic and functional mosaicism.
  • * To question the timing of mitochondrial origin relative to eukaryotic cell emergence.

Main Methods:

  • * Analysis of mitochondrial genome content.
  • * Comparative genomics of mitochondrial and bacterial proteomes.
  • * Integration of new data on organelle evolution.

Main Results:

  • * Mitochondria exhibit complex evolutionary pathways, not solely explained by Alphaproteobacteria.
  • * A significant portion of the mitochondrial proteome has non-Alphaproteobacteria origins.
  • * The classical endosymbiont hypothesis requires re-examination.

Conclusions:

  • * Mitochondria are a mosaic of genes with diverse evolutionary histories.
  • * The origin of mitochondria may coincide with the origin of the eukaryotic cell itself.
  • * Further research is needed to fully understand mitochondrial evolution.