Mitochondria: Chemical Energy Conversion

Related Posts:

Mitochondria: Chemical Energy Conversion (Campbell Biology)

Mitochondria are found in nearly all eukaryotic cells, including those of plants, animals, fungi, and most unicellular eukaryotes. Some cells have a single large mitochondrion, but more often a cell has hundreds or even thousands of mitochondria; the number correlates with the cell’s level of metabolic activity. For example, cells that move or contract have proportionally more mitochondria per volume than less active cells.

Each of the two membranes enclosing the mitochondrion is a phospholipid bilayer with a unique collection of embedded proteins. The outer membrane is smooth, but the inner membrane is convoluted, with infoldings called cristae. The inner membrane divides the mitochondrion into two internal compartments. The first is the intermembrane space, the narrow region between the inner and outer membranes. The second compartment, the mitochondrial matrix, is enclosed by the inner membrane. The matrix contains many different enzymes as well as the mitochondrial DNA and ribosomes. Enzymes in the matrix catalyze some of the steps of cellular respiration. Other proteins that function in respiration, including the enzyme that makes ATP, are built into the inner membrane. As highly folded surfaces, the cristae give the inner mitochondrial membrane a large surface area, thus enhancing the productivity of cellular respiration. This is another example of structure fitting function.

Mitochondria are generally in the range of 1–10 µm long. Time-lapse films of living cells reveal mitochondria moving around, changing their shapes, and fusing or dividing in two, unlike the static structures seen in electron micrographs of dead cells. These studies helped cell biologists understand that mitochondria in a living cell form a branched tubular network that is in a dynamic state of flux.


Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition.

Related Research

Research Article: REXO2 Is an Oligoribonuclease Active in Human Mitochondria

Date Published: May 31, 2013 Publisher: Public Library of Science Author(s): Francesco Bruni, Pasqua Gramegna, Jorge M. A. Oliveira, Robert N. Lightowlers, Zofia M. A. Chrzanowska-Lightowlers, Paul A. Cobine. Abstract: The Escherichia coli oligoribonuclease, ORN, has a 3′ to 5′ exonuclease activity specific for small oligomers that is essential for cell viability. The human homologue, … Continue reading

Research Article: Tom70 Is Essential for PINK1 Import into Mitochondria

Date Published: March 5, 2013 Publisher: Public Library of Science Author(s): Hiroki Kato, Qiping Lu, Doron Rapaport, Vera Kozjak-Pavlovic, Orian S. Shirihai. Abstract: PTEN induced kinase 1 (PINK1) is a serine/threonine kinase in the outer membrane of mitochondria (OMM), and known as a responsible gene of Parkinson’s disease (PD). The precursor of PINK1 is synthesized … Continue reading

Research Article: Casting Doubt on the Role of Mitochondria in Tumorigenesis

Date Published: November 4, 2005 Publisher: Public Library of Science Author(s): unknown Abstract: None Partial Text: Mitochondrial DNA (mtDNA) has been intensively studied over the past two decades, and point mutations, more commonly known as deletions, of this DNA are known to be involved in several syndromes. Unlike nuclear DNA, with 46 chromosomes, half from … Continue reading

Research Article: A Critical Reassessment of the Role of Mitochondria in Tumorigenesis

Date Published: November 4, 2005 Publisher: Public Library of Science Author(s): Antonio Salas, Yong-Gang Yao, Vincent Macaulay, Ana Vega, Ángel Carracedo, Hans-Jürgen Bandelt, Doug Turnbull Abstract: BackgroundMitochondrial DNA (mtDNA) is being analyzed by an increasing number of laboratories in order to investigate its potential role as an active marker of tumorigenesis in various types of … Continue reading