Cell metabolism 2 Flashcards
- Explain how the Glycerol-Phosphate Shuttle works
Cytosolic glycerol-3-phosphate dehydrogenase transfers electrons from NADH to DHAP → forming Glycerol-3-Phosphate
Membrane bound form of same enzyme transfers electrons to FAD, forming FADH2, also reforming DHAP from glycerol 3 phosphate
ekectrons are passed to co enzyme Q
- What is the purpose of the Glycerol Phosphate Shuttle
- Where in the body is the Glycerol-Phosphate Shuttle, used?
To carry electrons from NADH across to matrix
Skeletal Muscle Brain
- Explain Transamination with an example
Allows production of non-essential amino acids
Alanine + alpha-ketoglutarate → pyruvate + glutamate
when an amine group is transferred from one amino acid to a keto acid forming a new pair of amino and keto acids
- Where in the body is the Malate-Aspartate Shuttle used?
Liver
Kidney Heart
Outline the processes in the Malate-Aspartate Shuttle
NADH passed electron to Oxaloacetate (OAA), forming malate and NAD+
malate enters matrix by malate- alpha-ketoglutarate antiporter
malate loses an electron to NAD+, forming NADH and OAA
OAA reacts with glutamate to form alpha-keto-glutarate and aspartate
aspartate leaves matrix via the glutamate aspartate transporter
aspartate reacts with alpha keto glutarate to reform OAA and glutamate
the cycle repeats
- Explain how 38 ATP molecules are formed from glucose metabolism
Glycolysis → 2 ATP + 2 NADH → 8 ATP
Pyruvate Conversion → 2 NADH → 6 ATP 6 NADH → 18 ATP 2 FADH2 → 4 ATP 2 GTP → 2 ATP
- What is the purpose of Beta-Oxidation and where does it occur?
To produce Acetyl CoA
Mitochondria
- Outline the reaction converting Fatty Acids into Acyl CoA
Occurs outside of mitochondrial membrane
Fatty Acid + ATP + HS-CoA → Acyl CoA + AMP (adenosine monophosphate) + PPi Catalysed by Acyl CoA Synthase
- Why is AMP produced?
It is a high energy consuming reaction, so 2 high energy bonds are broken to go from ATP to ADP to synthesise the Acyl CoA
- what is the Carnitine Shuttle for?
- Outline the reactions in the Carnitine Shuttle
transport Acyl CoA species into the matrix for beta oxidation
Acyl from Acyl CoA added to the Carnitine to form Acyl Carnitine and CoA, catalysed by Carnitine acyltransferase I
Acyl Carnitine transported into matrix via Translocase Acyl Carnitine in matrix loses its Acyl group to a CoA to reform Acyl CoA in matrix and Carnitine, via carnitine acyl transferase 2
Carnitine exported into cytoplasm via Translocase
cycle repeats
- What are the symptoms of Primary Carnitine Deficiency?
- What is its inheritance pattern
Encephalopathies (damage or disease to brain)
Cardiomyopathies, muscle weakness and hypoglycaemia
Autosomal recessive
- When do the symptoms of Primary Carnitine Deficiency usually occur?
- What does a mutation in the gene SLC22A5 do?
During infancy or early childhood
Encodes a carnitine transporter resulting in reduced ability of cells to take up carnitine
- what are the reactants for the complete Beta Oxidation of 16C-Palmitoyl CoA
- what are the products from the complete Beta Oxidation of 16C-Palmitoyl CoA?
palmitoyl CoA, 7 FAD, 7NAD+, 7H20, 7 CoA
8 Acetyl CoA, 7 FADH2, 7 NADH
- What occurs when fat breakdown predominates over glucose metabolism and why does this accur ?
- what are the ketone bodies?
Ketone bodies are formed, because beta oxidation can’t continue anymore as oxaloacetate is needed, but it is being used to remake glucose in gluconeogenesis (as glucose is low)
during fasting acetyl CoA forms acetoacetate, D-3 hydroxybutyrate and acetone
- What is Beta Oxidation?
- What is the beta oxidation equation?
process of producing acetyl CoA from fatty acids
first it is converted to a acyl CoA species
then it undergoes a series of reactions in the matrix including oxidation, hydration, thiolysis
Palmitoyl CoA + 7 FAD + 7 NAD + 7 CoA + 7 H2O → 8 Acetyl CoA +7 FADH2 + 7 NADH
- What are the three differences between Beta-Oxidation of Fatty Acids and the synthesis of Fatty Acids?
Carrier Proteins: CoA vs ACP
Reducing Power: NAD+ vs NADPH/FAD Locations: Mitochondrial Matrix vs Cytoplasm
- What is the overall equation for lipogenesis?
Acetyl CoA (C2) + 7 Malonyl CoA (C3) + 14 NADPH + 14 H+ → Palmitate (C16) + 7 CO2 + 6H20 + 8 CoA-SH + 14 NADP+
which two enzymes does fatty acid synthesis use?
process of lipogenesis?
acetyl co A carboxylase and fatty acid synthase
fatty acids formed sequentially by darcarboxylation condensation reactions involving malonyl CoA and Acetyl CoA
following each round of elongation, fatty acid undergoes reduction and dehydration by sequential action of
- ketoreductase
- dehydratase
- enol reductase
the gorwing fatty acyl chain is linked to an acyl carrier protein
what are the steps to the krebs cycle?
Can I Also Sell Sex For Money, Officer
citrate (6 C) isocitrate (6 C) Alpha- Ketoglutarate (5) succinyl Co A (4) succinate fumerate malate oxaloacetate then acetyl added to react with OAA and cycle starts again
where are the NADH, CO2, FADH2, and GTP formed
NADH and CO2 between isocitrate and alpha keto glutarate
NADH between alpha keto glutarate and succinyl CoA
GTP between succinyl CoA and Succinate
FADH2 between succinate and fumerate
NADH between malate and Oxaloacetate
purposes of amino acid degradation?
remove amine group to be excreted as urea
carbon skeleton either for gluconeogenesis or to feed into TCA cycle
- How many net molecules of ATP are generated from metabolism of Palmitate?
7 FADH2 = 7 x 2 =14
7 NADH = 7 x 3 = 21
8 Acetyl CoA = 12 x 8 = 96 (Because it enters the Kreb’s Cycle and undergoes oxidative phosphorylation)
2 Phosphate bonds are hydrolysed at start of beta oxidation to produce Acyl CoA = 2 14 + 21 + 96 - 2 = 129
How are ketone bodies synthesised
2 acetyl Co A to acetoacetyl co A via beta thiolase
the HMG - CoA synthase to form HMG coA
forms acetoacetate via HMG CoA lyase
forms either:
D-3 hydroxy butyrate via d-3-hydroxybutyrate dehydrogenase, forming an NAD+ from NADH and H+
or, acetone via acetoacetate decarboxylase
- What is the Warburg Effect?
Mutations in genes of Fumerase, Succinate dehydrogenase Isocitrate Dehydrogenase, decreases Kreb’s Cycle activity which enhances anaerobic glycolysis
Preferential generation of lactate from glucose even in increased O2 availability
occurs in cancers
What is Acyl CoA dehydrogenase
what are the different lengths
catalyse the initial step in each cycle of beta oxidation
short chain - 6c
medium chain- 6-12
long chain 3 hydroxy acyl CoA dehydrogenase- c13-c21
very long chain- C22
what is MCADD
what must someone do if they have been diagnosed
medium chain acyl CoA dehydrogenase deficiency
autosomal recessive
never go without food for more than 10-12 hours
high carb diet
people with illness resulting in appetite loss or severe vomiting may need IV glucose
to make sure body is not dependant on fatty acids
