Practical E2 Flashcards
phosphorylation cannot occur without oxidation of substrates and utilisation of oxygen, and conversely the rate of oxidation of substrates , is controlled by the availability of ADP to be phosphorylated (to zdjęcie poniżej
[zdjęcie 1]
The mitochondrion: outer membrane functions: [zdjęcie 2]
- relatively freely permeable to substrates
- phospholipase
- fatty acid elongation
- triacylglycerol synthesis from fatty acids
The mitochondrion: inter-membrane space functions: [zdjęcie 2]
- nucleotide metabolism
- transamination of amino acids
- various kinases
The mitochondrion: Inner membrane functions: [zdjęcie 2]
• regulation of transport of substrates, etc
The mitochondrion: Matrix functions: [zdjęcie 2]
- fatty acid oxidation
- citric acid cycle
- variety of other dehydrogenases
- enzymes for mitochondrial replication
- DNA for some mitochondrial proteins
The mitochondrion: Cristae functions: [zdjęcie 2]
- electron transport
- oxidation of coenzymes linked to reduction of oxygen to water
The mitochondrion: Primary particles functions: [zdjęcie 2]
• Oxidative phosphorylation (ADP + Pi to form ATP)
The utilisation of oxygen during the reaction is measured using …
the Clark oxygen electrode [zdjęcie 3] We do not need to know the structure of this equipment, but just in case: The reaction chamber is separated from the electrodes by a teflon membrane, which permits oxygen to diffuse from the reaction buffer into the potassium chloride solution that bathes the electrodes: a platinum cathode and a silver anode. A voltage is applied between the electrodes and the resulting current (approx. 1 µA) is proportional to the concentration of oxygen.
to set 0% saturation in the oxygen electrode, a strong reducing agent must be used such as …
sodium dithionite
At the cathode of the oxygen electrode, …
oxygen is reduced to water: [zdjęcie 4]
At the anode of the oxygen electrode, ….
metallic silver is oxidised to silver chloride: [zdjęcie 5]
In the electrode you will be using in these studies, 100% saturation with oxygen =
1327 nmol O.
Two groups of coenzymes react directly with substrates:
the nicotinamide nucleotides and the flavin coenzymes.
Which of the carriers undergo oxidation / reduction reactions reactions involving transfer of both hydrogen ions and electrons?
The nicotinamide nucleotides, flavins and ubiquinone
Which of the carriers undergo oxidation / reduction reactions reactions involving transfer of electrons ONLY..
the cytochromes and non-haem iron proteins
In NAD the reactive group is .. In the oxidised coenzymes this has a … charge;
the nicotinamide ring positive [zdjecie]
In different enzymes flavins may be present as : (3)
- covalently-bound riboflavin,
- tightly (but non-covalently) bound riboflavin monophosphate (which is sometimes known as flavin mononucleotide, FMN)
- flavin adenine dinucleotide (FAD). [zdjecie]
The flavin coenzymes undergo redox reactions …
either as a single two-electron reaction or as two single-electron reactions [zdjecie]
Ubiquinone undergoes …. redox reaction ….
a two-electron in two single electron steps, via a half-reduced emiquinone radical.
The cytochromes consist of a ….chelating a central iron atom in the non-haem iron proteins the iron atoms are chelated by …
tetrapyrrole (porphyrin) ring sulphydryl groups of cysteine residues and inorganic sulphide (hence the alternative name of iron sulphur proteins).
• Protoporphyrin IX (haem) is non-covalently bound by histidine residues in the protein in haemoglobin, myoglobin, catalase and cytochromes b, b1 and P450.
sd
• Haem C is covalently bound to cysteine residues of the protein in cytochromes c and c1.
dsa
• Haem A is anchored in the membrane lipid by a long hydrophobic tail in cytochromes a and a3.
sad
