Cell Metabolism 1+2 Flashcards
What is this process called?
Glycolysis
Identify each type of reaction
Identify enzyme, product, type of reaction
Step 1
Identify enzyme, product, type of reaction
Step 2
Identify enzyme, product, type of reaction
Step 3
Identify enzyme, both products, type of reaction
Step 4
Identify enzyme, product, type of reaction
Step 5
Metabolic Disease:
Which glycolytic enzymopathy is fatal?
Deficiency in TPI is the only glycolytic enzymopathy that is fatal, with most sufferers dying within the first 6 years of their lives.
Identify enzyme, product, type of reaction
Step 6
Identify enzyme, product, type of reaction
Step 7
Identify enzyme, product, type of reaction
Step 8
Identify enzyme, product, type of reaction
Step 9
Identify enzyme, product, type of reaction
Step 10 (Final Step)
Which steps are irreversible in glycolysis?
Steps 1,3 and 10
(hexokinase, PFK, pyruvate kinase)
Which step commits the cell to glycolysis and traps glucose inside the cell?
Step 1 - Phosphorylation of Glucose into Glucose 6-P
What is the net change in ATP for glycolysis?
+2
(-2+4=+2)
Which steps consume ATP?
Steps 1,3
(hexokinase, PFK)
Which steps produce ATP?
Steps 7 and 10
(PG kinase and pyruvate kinase)
Which step is a dehydration reaction?
Step 9
(Water and Phosphoenolpyruvate produced)
How many NADH molecules produced in glycolysis and which steps?
2xNADH in Step 6
What is the parallel pathway to glycolysis which is used in anabolic reactions to generate biosynthetic molecules called?
Pentose-Phosphate Pathway (PPP)
What molecule does NADH reduce, which is also a vital antioxidant?
Glutathione
Alcoholic Fermentation
Identify enzyme and product
Decarboxylation of Pyruvate
Alcoholic Fermentation
Identify enzyme and product
Dehydrogenation of Acetaldehyde
Which organism performs alcoholic fermentation and under what conditions?
Yeast, under anaerobic conditions
Generation of Lactate
Identify enzyme and product
Dehydrogenation of Pyruvate
Generation of Lactate
Where in the Mammalian body does lactate generation occur and when?
In muscles, when oxygen is a limiting factor
What is the common purpose of alcoholic fermentation and lactate generation?
NAD+ Regeneration
Which molecule is used as an ATP buffer?
Creatine phosphate
Identify enzyme and product
What is the order of main ATP storage in muscles during a long exercise?
stored ATP-> CP-> Anaerobic metabolism-> Aerobic metabolism
Identify enzyme and all three products
Why is addition of CoA necessary for TCA cycle?
Thioester bond is readily hydrolysed enabling acetyl CoA to donate acetate easily
What are the cofactors of PDH complex?
Thiamine (B1) pyrophosphate, Lipoic Acid and FAD
(in addition to NAD+ and CoA which are also substrates)
What is the cause of Beri-Beri disease?
Thiamine deficiency affecting PDH complex causes symptoms such as peripheral nerve damage, muscle weakness and reduced cardiac output.
Which 3 amino acids can be substrates of kinases?
Serine, threonine and tyrosine
What type of phosphorylation is glycolysis?
Substrate-level phosphorylation
What does high serum LDH indicate?
Possible stroke or MI
What is this cycle called and where does it take place?
TCA or Kreb’s or Citcric Acid Cycle
- takes place in mitochondrial matrix
What is the total production of TCA cycle per one glucose?
Two turns per glucose:
6xNADH
2XGTP
2XFADH2
4XCO2
What reaction is this and which group of molecules react?
Transamination (Group Transfer)
An amino acid and a keto acid react
What is the purpose of this transamination reaction?
Alanine is converted into pyruvate, so it can join the TCA cycle (through link reaction)
Identify enzyme and one product
Name all the substrates of TCA cycle respectively, starting with Acetyl CoA
Acetyl Coa + Oxaloacetate → Citrate → Isocitrate → a-Ketoglutarate → Succinyl CoA → Succinate → Fumarate → Malate → Oxaloacetate
Identify enzyme and product
Name the enzymes
Name the enzymes
Which steps produce NADH in TCA cycle?
Isocitrate → a-Ketoglutarate
a-Ketoglutarate → Succinyl CoA
Malate → Oxaloacetate
Which step produces GTP in TCA cycle (later converted to ATP)?
Succinyl CoA → Succinate
Which step produces FADH2?
Succinate → Fumarate
What are the ketogenic amino acids?
Leucine
Lysine
Isoleucine
Tryptophan
Tyrosine
Phenylalanine
What do ketogenic amino acids form?
Ketone bodies
Through what do the ketogenic amino acids enter TCA cycle?
Through Acetly CoA or Acetoacetyl CoA (which is then converted into Acetoacetyl CoA)
How do the glucogenic amino acids enter TCA cycle?
Pyruvate, Oxaloacetate, Fumarate, Succinyl coA, a-Ketoglutarate
How are the electrons from NADH transferred inside the mitochondrion?
The Glycerol phosphate shuttle and the Malate-Aspartate shuttle
Where in the body are the specific electron shuttles used?
The Glycerol phosphate shuttle – skeletal muscle, brain
The Malate-Aspartate shuttle – liver, kidney and heart
Which enzyme transfers electrons from NADH to which molecule?
Cytosolic glycerol 3-phosphate dehydrogenase transfers electrons from NADH to DHAP to generate glycerol 3-phosphate
What is Step 2 of the Glycerol phosphate shuttle?
Mitochondrial glycerol 3-phosphate dehydrogenase transfers the electrons to FAD. These then get passed to co-enzyme Q, part of ETC
What types of reactions are happening in the Malate-Aspartate shuttle?
Redox reactions
What are the enzymes and protein channels in the Malate-Aspartate shuttle called?
Enzymes:
AT = aspartate transaminase
MDH = malate dehydrogenase
Protein Channels:
Glutamate-aspartate antiporter
Malate-α-ketoglutarate antiporter
reactant is α-ketoglutarate
products are glutamate and oxaloacetate
How many ATP molecules produced per NADH and FADH2?
3x ATP per NADH
2x ATP per FADH2
What type of reaction is this?
Transamination reaction
What is the first step of β-oxidation of fatty acids?
Fatty acids are converted into an Acyl CoA species converting ATP to AMP
Mutations in which TCA cycle enzymes might favour aerobic glycolysis (supporting malignancy)?
Isocitrate dehydrogenase, Succinate dehydrogenase and Fumarase
How does the Acyl CoA generated from β-oxidation enter mitochondrial matrix?
Couples with carnitine
What are the enzymes and protein channel called in the carnitine shuttle?
What happens inside the cells in primary carnitine deficiency?
Reduced carnitine transporter activity causes carnitine levels inside the cells to drop which further prevents β-oxidation of fatty acids.
What are the products of one turn of β-oxidation cycle?
1X NADH
1X FADH2
1X Acetyl CoA
1X Acyl CoA species, 2 carbons shorter than the original
What are the products of β-oxidation of palmitoyl CoA (16C)?
In 7 β-oxidation cycles:
8 Acetyl CoA+7NADH+7FADH2
What does Acetyl CoA from β-oxidation produce when fasting and what are they collectively. known as?
Ketone Bodies: Acetoacetate, D3HB and. Acetone
Which two enzymes does fatty acid biosynthesis involve?
Acetyl CoA Carboxylase and Fatty Acid Synthase
What is the growing fatty acid chain linked to in lipogenesis?
Acyl Carrying Protein (ACP)
Carriers, Reducing power and Locations of Lipogenesis vs β-oxidation
Lipogenesis: ACP, NADPH and cytoplasm
β-oxidation: CoA, NAD+/FAD+ and mitochondrial matrix
Which two molecules react in decarboxylative condensation reactions of lipogenesis?
Acetyl CoA and Malonyl CoA
What are the reactants of lipogenesis that give palmitate (16C) as a product?
Acetyl CoA (2C) + 7 Malonyl CoA (3C) + 14 NADPH
What are the byproducts of lipogenesis of palmitate (16C)?
7 CO2 + 6 H2O + 8 CoA + 14 NADP+
Where does elongation of acyl group to make fatty acids longer than 16C occur in the cell?
Mitochondria and ER
What is the group of enzymes required for desaturation of fatty acids?
Fatty acyl CoA desaturases
Which enzyme turns palmitate and stearate into palmitoleic acid and oleic acid?
∆-9 desaturase as it generates a double bond on the 9th C
Which parts of the adult human body perform de novo fatty acid biosynthesis?
Liver, adipose tissue and lactating breast
Why is lipogenesis reactivated in some cells unusually?
To act as an energy source for cancer cells
How chain lengths separated in acyl CoA dehydrogenases?
Short-chain 1-6C
Medium-chain 6C-12C
Long-chain 13C-21C
Very long-chain >22C
What is affected in patients with Medium-chain acyl CoA dehydrogenase deficiency (MCADD)?
Fatty metabolism is affected, so they should rely highly on carbohydrates and avoid fasting for long periods