Energy II Flashcards
Acetyl CoA, Mitochondria, Oxygen
Where does the citric acid cycle occur? [1 mark]
Matrix of the mitochondria
Enzymes involved in the citric acid cycle? [4 marks]
- Pyruvate dehydrogenase
- citrate synthase
- isocitrate dehydrogenase
- alpha ketogluterate dehydrogenase
How much NADH is made per glucose? [2 marks]
- 2 when pyruvate is converted to acetyl CoA
- 6 in citric acid cycle
How much FADH2 is made per glucose? [1 mark]
2
How much GTP is made per glucose? [1 mark]
2
How much CO2 is made per glucose? [2 marks]
- 2 when pyruvate is converted to acetyl CoA
- 4 in the citric acid cycle
Acetyl CoA formation [1 mark]
It is essentially irreversible
What is acetyl CoA used for? [2 marks]
- either for the citric acid cycle
- or to form fatty acids
What inhibits pyruvate dehydrogenase? [1 mark]
Its products (NADH and acetyl CoA)
What activates pyruvate dehydrogenase? [2 marks]
- ADP
- pyruvate
What inhibits citrate synthase?
Its product (citrate)
What inhibits isocitrate dehydrogenase? [2 marks]
- NADH
- ATP
What activates isocitrate dehydrogenase? [1 mark]
ADP
What inhibits alpha keto gluterate dehydrogenase? [3 marks]
- NADH
- ATP
- succinyl CoA
What activities does pyruvate dehydrogenase have? [2 marks]
- Kinase
- Phosphatase
What does calcium facilitate in muscle? [1 marks]
ATP generation
What increases calcium in the liver and how? [2 marks]
- Adrenalin
- via the activation of alpha adrenergic receptor and IP3.
What is Inositol triphosphate?
- a secondary messenger
- mobilises Ca2+ for muscle contraction
What does insulin do in liver and adipose tissue? [4 marks]
- stimulates the phosphatase
- activates dehydrogenase
- increases amount of acetyl CoA
- funnels glucose to fatty acid synthesis
What causes beriberi? [1 mark]
- Deficiency in thiamine (Vitamin B1)
What is a prosthetic group for pyruvate dehydrogenase and alpha ketogluterate dehydrogenase? [1 mark]
Thiamine pyrophosphate
What are the effects of beriberi? [7 marks]
- higher serum levels of pyruvate and alpha ketogluterate
- lack of ATP causes damage to PNS, limb pain, muscle weakness and distorted skin sensation.
- enlarged heart
- insufficient cardiac output
What is coenzyme Q10? [1 mark]
An ubiquitous component of the ETC
What is the function of cytochrome b-c1 complex? [1 mark]
Catalyses the reduction of cytochrome c
What are the functions of cytochrome c? [3 marks]
- Haem group accepts electrons from b-c1 complex
- Transfers electrons to complex IV
- Involved in the initiation of apoptosis
How much H+ from NADH is pumped out of the matrix?
10
How much H+ from FADH2 is pumped out of the matrix?
6
How much ATP is made from NADH?
3
How much ATP is made from FADH2?
2
How is heat generated in infants? [1 mark]
The transport of electrons is uncoupled from ATP synthesis
Brown fat [2 marks]
- Dense in mitochondria
- less ATP is generated
What are the symptoms of mitochondrial diseases? [3 marks]
- Fatigue
- Epilepsy
- Dementia
What causes mitochondrial diseases? [1 mark]
Mutations in genes for proteins in ETC
What is the metabolic consequence of mitochondrial diseases?
Congenital lactic acidosis
What effect does ATP and G6P have on glycogen synthase? [1 mark]
It activates it
What effect does ATP and G6P have on glycogen phosphorylase? [1 mark]
It inactivates it
What does protein kinase A do to glycogen synthase? [2 marks]
- it phosphorylates it
- this inactivates it
What does protein kinase A do to glycogen phosphorylase? [2 marks]
- it phosphorylates it
- this activates it
What does protein phosphatase-1 do to glycogen synthase? [2 marks]
- dephosphorylates it
- this activates it
What does protein phosphatase-1 do to glycogen phosphorylase? [2 marks]
- dephosphorylates it
- inactivates it
When is glycogen synthase activated? [1 mark]
In time of plenty (of glucose)
When is glycogen phosphorylase activates? [1 mark]
Activated when glucose is in short supply
When is the pentose phosphate pathway activated? [1 mark]
When there is a lot of glucose-6-phosphate
What is the oxidative phase of the pentose phoshate pathway? [2 marks]
- The formation of ribulose-5-phosphate from G6P
- The irreversible part
What are the products of the oxidative phase? [2 marks]
- 2 NADPH
- CO2
What is the non oxidative phase of the pentose phosphate pathway? [2 marks]
- The conversions of ribulose-5-phosphate to ribose-5-phosphate
- The reversible part
What is NADPH useful for? [2 marks]
- synthesis of antioxidants (i.e. glutathione)
- synthesis of fatty acids
How do antioxidants protect from oxidative stress?
They donate electrons to neutralise oxygen radicals
What is ribose-5-phosphate important for? [3 marks]
- Nucleotide/DNA synthesis
- Synthesis of some coenzymes
- metabolism from its conversion to other sugars
What fuel can erythrocytes use? [1 mark]
Glucose
What is the daily body and brain requirement for glucose? [2 marks]
- 160g for the body
- 120g for the brain
What are the total body reserves for glucose? [1 mark]
210g
What does gluconeogenesis do to make glucose? [1 mark]
Converts pyruvate to glucose
Where does gluconeogenesis take place? [2 marks]
- usually in the liver
- but also in the kidneys during starvation
What enzyme must glucose-6-phosphatase overcome?
Hexokinase
What enzyme must fructose bisphosphatase overcome?
Phosphofructokinase
What enzymes overcome pyruvate kinase? [2 marks]
- Pyruvate carboxylase
- phosphoenol pyruvate carboxykinase
Which enzymes are inhibited by glucagon? [2 marks]
- Pyruvate kinase
- Phosphofructokinase
What is pyruvate an intermediate for? [2 marks]
- Lactate
- Some amino acids [e.g. alanine]
How does oxaloacetate leave the mitochondria? [2 marks]
- converted to malate and exits via carrier
- is converted back to oxaloacetate in the cytosol
How does pyruvate enter the mitochondria? [1 mark]
Via a carrier protein
