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Mitochondrial Oxidative Phosphorilation and Genetics. Abigail Hardy. The Mitochondria. Thousands of mitochondria in high energy areas Contact sites facilitate the entry of protiens into matrix Produces ~90% of the cellular ATP in eukaryotic cells. Major Protien Complexes.
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Mitochondrial Oxidative Phosphorilation and Genetics Abigail Hardy
The Mitochondria • Thousands of mitochondria in high energy areas • Contact sites facilitate the entry of protiens into matrix • Produces ~90% of the cellular ATP in eukaryotic cells
Complexes I to IV, in addition to other components, act together as an electron transport chain Protons in intermembrane space form an electrochemical gradient, which provides potential energy used by complex V for the phosphorylation of ADP to ATP. Membrane channel protien (ANT) transports ATP out and ADP into matrix 1:1 ratio of transfer Both ADP and ATP move freely through the outer membrane Oxidative Phosphorylation
Mitochondria have their own genetic apparatus Circular (16,568 bp) 2-10 separate mitochondrial gemomes in matrix Carries information for: 2 rRNAs 22 tRNAs 13 proteins The 13 proteins encoded are involved in OXPHOS functions Nuclear genes encode about 70 additional protiens that make up the OXPHOS system A mitochondrion is the joint product of two different genetic systems Mitochondrial DNA
Mitochondrial Replication • During mitochondrial multiplication each genome is randomly distributed to a daughter mitochondrion • Does NOT follow the Mendelian pattern of inheritance b/c not part of chromosomal system • Details of mitochondrial reproduction are not known
Mitochondrial Genetics • Mitochondria of the zygote come from the oocyte (mother) and almost never the sperm (father) • If the same set of symptoms in a number of various multigenerational families is inherited only from affected females and almost never from affected males, then there is a strong likelihood that it is caused by a mutation in one of the mitochondrial DNA genes
Human oocyte loses mitochondria as it matures through the genetic bottleneck Mitochondria are randomly distributed into daughter cells Mitochondrial Mutation Load= the ratio of mutated to normal mitochondrial DNA Homoplasmy= all mitochondria of a cell or tissue have the same genome Heteroplasmy= contains both mutant and wild-type genomes Proportion of mutant to wild-type M. DNA determines if energy shortage occurs Threshold for phenotypic expression Oocyte Mitochondria
Bibliography • Widmaier, E.P., Raff, H., Strang, K.T. Vander’s Human Physiology: The Mechanisms of Body Function. 10th ed. Boston: McGraw-Hill, 2005. • www.cbs.dtu.dk/staff/ dave/roanoke/bio101ch06.htm