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71 Cards in this Set
- Front
- Back
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What do Mitos and Chondrion mean in greek?
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Threadlike + granules
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What did mitochondria evolve from?
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purple bacteria
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How did mitochondria evolve?
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By endosymbiosis
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Importance of mitochondria:
(2 things supplied) |
-Major source of ATP
-Major supplier of proteins and enzymes for mitochondrial biogenesis and functions |
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What has to be coordinated in order for proper synthesis, assembly, and functioning of ETC enzymes?
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Mitochondrial and Nuclear DNA
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2 Major functions of Mitochondria:
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1. Complete oxidative metabolism of Carbs, AAs, and FAs
2. Coupling of ETC and oxidative phosphorylation -> ATP |
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4 Compartments of the Mitochondrion:
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1. OMM outer membrane
2. IMS inter space 3. IMM inner membrane 4. Matrix matrix |
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What special things are in the outer membrane?
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-Porins
-Receptors |
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What special things are in the Intermembrane space?
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Cytochrome c
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What special things are in the inner mito membrane?
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-Cardiolipin
-ETC enzymes -Transport proteins |
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What special things are in the Matrix?
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-Krebs cycle enzymes
-Peptidases -mtDNA |
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What can go through a porin in the OMM?
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Things less than 1 kDa large
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What is cytochrome c?
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The substrate for Complex IV in the ETC.
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What is cardiolipin?
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A receptor for creatine Kinase in the inner mito membrane.
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What is the structure of the IMM like?
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-70% protein
-30% lipid |
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What important enzymes are in the IMM?
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The respitory chain enzymes
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Which one is cytochrome c oxidase?
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Complex IV (last one)
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Which one is NADH dehydrogenase?
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Complex I
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Which one is cytochrome c reductase?
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Complex III
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Which one is succinate dehydrogenase?
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Complex II
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What is TIM?
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Translocase of Inner Membrane - a transport protein that uses ATP to bring things in and ADP to get them out.
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5 things in the mitochondrial matrix:
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1. Krebs cycle enzymes
2. Peptidases 3. Mitochondrial DNA 4. Ribosomes 5. Calcium granules |
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What is the intermediary for coupling of the ETC and oxidative phosphorylation?
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the proton motive force that is generated by passing protons into the intermembrane space as electrons flow thru ETC.
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What is the theory called?
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Chemiosmotic theory
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2 Components to the PMF:
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-Membrane potential LARGE force
-H+ gradient -> SMALLER force |
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What direction is the net force of the PMF directed?
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Inside - toward the matrix
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What 3 things are driven by the active transport of the PMF?
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-ADP/ATP antiport
-H+/Pi symport -H+/Pyruvate symport |
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So in terms of electrical gradients the matrix is what?
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Negative
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Which protein in the mitochondria is not bigenomic?
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Succinate dehydrogenase
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How do mitochondria multiply?
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By binary fission of existing mitochondria
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How much DNA is in mitochondria?
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~16,500 bp
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What is the DNA in mitochondria like?
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-Heavy and Light chains
-Double-stranded -Closed circular -Compact -no introns |
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What does mitochondrial dna encode for?
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2 rRNAs
22 tRNAs 13 polypeptides |
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What is the nature of all that DNA? (where it comes from)
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Bigenomic - composed of both nuclear and mitochondrial DNA except for succinate dehydrog.
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What is replication of mtDNA like?
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Bidirectional and asynchronous
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what is the D loop?
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The portion of the DNA loop that contains mitochondrial DNA
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What is most of the DNA in ring a transcript for?
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rRNA
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Where do we get our mitochondrial DNA from?
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Maternal inheritance
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Does mtDNA replication depend on cell division?
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No
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What happens to mtDNA during mitosis and meiosis?
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It undergoes replicative segregation
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How does mtDNA accuracy compare to nuclear DNA?
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Mutation rate is 10-20x higher
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What is the Threshold expression for mtDNA mutation?
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The threshold of accumulations of mtDNA mutations; when reached dysfunction will occur.
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What does the universal codon for Arg encode in mitochondria?
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STOP
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What does the universal codon for Ile encode in mitochondria?
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Methionine
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What does the universal codon for STOP encode in mitochondria?
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Tryptophan
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What does nuclear DNA encode in mitochondria?
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-All enzymes of matrix
-protein/RNA import machinery -Transcription factors for mtDNA transcription and replication |
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So what controls the translation of specific mitochondrial mRNAs?
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the NUCLEAR genome
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How much mitochondrial protein has to be imported?
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>90%
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What is the mechanism for protein import into mitochondria?
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Targeting sequence
(signal, leader, or presequence) |
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Targeting sequence
-length -rich amino acids -structure -processing |
-20-70 aa long
-rich in Ser/Thr at N-term -can be amphipathic -cleaved by specific peptidases in mitochondria |
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What is required for proteins to be able to be imported?
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Unfolding via HSP70 + ATP
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What are the Import receptors?
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TOMs
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What are the insertion proteins?
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GIP
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What does GIP match up with?
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TIM
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What is the translocation motor?
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mt Hsp70
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What happens after protein import?
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-Proteolytic removal of sequence
-Refolding, assembly, and intramito sorting |
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What 3 proteins aid in the things that happen after import?
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-Chaperonins
-Hsp60 -mtHsp70 |
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3 possible sources of mutation in mtDNA:
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-Nuclear DNA
-Cytoplasmic DNA (mt) -X-linked |
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what type of inheritance will be seen in each type of mutation?
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-Nuclear DNA: mendelian
-Cytoplasmic: maternally transmitted -X-linked |
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3 causes of mtDNA mutation:
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1. Linked to IMM - the source of oxygen radicals
2. Lacks protective histones 3. Has limited repair system |
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What disease is caused by missense mutations in mtDNA?
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LHON - leber's hereditary optic neuropathy
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What 2 diseases result from tRNA point mutations that affect protein synthesis in mtDNA?
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MERRF
MELAS |
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MERRF
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Myoclonus epilepsy and ragged red fibers
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MELAS
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mitochondrial encephalomyopathy, lactic acidosis, strokelike symptoms
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What 2 disease result from insertion-deletion mutations of mtDNA?
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1. KSS (kearns sayre)
2. PEO (progressive external ophthalmoplegia) |
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What kind of damage occurs in insertion-deletion mutations?
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Deletions of 1.3-7.6 kb flanked by direct repeats of nts
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Are insertion-deletion mutations inherited?
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No - usually no family history
-new mutations that occur during development |
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What are 3 diseases of aging where mitochondrial dysfunctions are implicated?
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-normal aging
-parkinsons -alzheimers |
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What is an early event in apoptosis involving mitochondria?
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Release of cytochrome c
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What blocks the release of cytochrome c?
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Bcl-2 family proteins
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So what is the result of Bcl-2 proteins?
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Block apoptosis and promote cell survival.
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