Lecture 5 Flashcards
What are mitochondria derived from
Common ancestral organelle from endosymbiotic alphaproteobacterium (oxygen-using non photosynthetic prokaryote) into a host related to archaea
Mitochondria structure
-intermembrane space
-inner and outer membrane
-inner membrane formed into cristae
-matrix
-F0 and F1 complexes
How are mitochondria moved around the cell?
Moved by microtubules of the cytoskeleton
Where are mitochondria found in cells
Regions with high ATP consumption/energy requirement
Outer membrane of mitochondria
-Similar to most other eukaryotic membranes
-Major protein component is porin which forms large aqueous channels
Inner membrane of mitochondria
Contains three types of membrane complexes:
-electron transport chain
-ATP synthase
-specific transporters of metabolites (depending on cell type)
What is more controlled inner or outer membrane
Inner membrane
Cristae
-Increase surface area
-Energy inducing membrane
-Impermeable to most small ions as part of inner membrane
Matrix
Inside of the mitochondria (inside membranes)
-enzymes in krebs cycle
-ribosomes
-mitochondrial DNA
ATP structure
triphosphate, ribose and adenine
Generation of energy to synthesise ATP
-via oxidation of organic molecules (diet)
-the electrons lose potential energy when they end up being shared unequally ie spending more time near electronegative atoms such as oxygen
NAD full name
nicotinamide adenine dinucleotide
How many electrons and protons reduce NAD+
2 electrons and 1 proton from an organic molecule makes NADH
Why must the reaction of hydrogen and oxygen be done in multiple steps in the ETC
Hydrogen+oxygen-> water causes a large amount of energy in the form of heat and light ie an explosion
Glycolysis steps
- Glucose (from diet)
- Immediately ATP is hydrolysed and the inorganic phosphate phosphroylates the glucose
- Glucose-6-phosphate is converted to fructose 6-phosphate
- Phosphofructokinase transfers a phosphate group from ATP to the opposite end of the sugar
- Aldolase ‘cleaves’ the sugar molecule into two different 3 carbon sugars
- The sugar is oxidised by the transfer of electrons to NAD+
- Using energy from step 6 a phosphate is attached making a high energy product (subtrate level phosphorylation)
- The phosphate is removed to ADP forming pyruvate
Krebs Cycle (citric acid cycle or tricarboxylic acid)
- Acetyl coA reacts with oxaloacetate to form citrate releasing coenzyme A
- Citrate is converted to isocitrate releasing water
- Isocitrate is oxidised in multiple steps to reform oxaloacetate forming 3 NADH and 1 FADH2
Electron transport chain:
- High energy electrons from NADH and FADH2 are passed onto protein complex
- The protein complex passes to the next protein in the chain which releases energy and reduces the energy of the electrons
- step 2 continues down the chain and reduces the electron energy
- Eventually the electrons are passed on oxygen to generate water
- Energy used to produce a H+ gradient across the inner mitochondrial membrane
NO ATP IS MADE IN THE ELECTRON TRANSPORT CHAIN
Chemiosmosis to produce ATP
- High H+ in intermembrane space causes a gradient
- H+ moves down ATP synthase causing a complimentary change
- This change produces ATP
ATP synthase structure
F0 portion is a H+ channel
F1 head is the site of ATP synthesis
Movement of H+ through F0
-causes rotation of the rotor and central stalk while the stator keeps the enzymatic F1 stationary
-provides energy for ATP synthesis
-10H+ moving back into the matrix generates ~3 ATP molecules
Mitochondrial poisons: Cyanide
Prevents the passage of electron from one of the cytochromes thereby blocking the ETC. Very fast
Mitochondrial Poisons: 2,4-Dinitrophenol
Makes the inner membrane leaky to H+ so that a gradient cannot be established. The ETC still works but just creates a lot of heat - ‘burnt from the inside out’
What is brown fat
Specalised type of adipose tissue to keep warm
Mycoclonic epilepsy and ragged-red fiber disease
-mitochondrial genetic disease
-mutation in the mitochondrial encoded tRNA Lys gene
-affects the translation of mitochondrial proteins
-abnormal mictochondria morphology
-multisystem disease which mainly effects muscles and nerves (epilepsy and weakness)
-no cure
