E1.2 metabolism overview Flashcards
What is the purpose of catabolic metabolism?
To oxidize macronutrients for ATP production
Catabolic metabolism involves breaking down molecules to release energy.
What are the main macronutrients oxidized for ATP production?
- Fatty acids
- Carbohydrates
- Amino acids
- Ethanol
These macronutrients serve as energy sources in human metabolism.
Which metabolic process occurs in the mitochondria and involves NADH and FADH2?
Electron Transport Chain (ETC)
The ETC is crucial for reoxidizing NADH and FADH2 to produce ATP.
What happens to pyruvate if NADH is not efficiently re-oxidized?
It becomes lactate, leading to lactic acidosis
This occurs when the Electron Transport Chain is impaired.
What enzyme is responsible for converting pyruvate to acetyl-CoA?
Pyruvate dehydrogenase
This conversion is a key step in linking glycolysis to the TCA cycle.
Fill in the blank: The first step in the catabolism of all sugars that traps them inside cells is _______.
Glycolysis
Glycolysis is the initial metabolic pathway for sugar breakdown.
What is the role of lactate production during hypoxia?
It increases as a response to mitochondrial dysfunction
Lactate serves as an alternative energy source when oxygen is low.
Which hormone increases blood glucose levels?
Glucagon
Glucagon promotes glycogen breakdown in the liver to raise blood sugar.
True or False: Most cells can convert fatty acids into glucose.
False
Fatty acids cannot be converted to glucose, with rare exceptions for odd-chain fatty acids.
What are the substrates for gluconeogenesis?
- Glycerol
- Lactate
- Alanine
- Pyruvate
These substrates are utilized to synthesize glucose during fasting.
What is the metabolic hub of the body responsible for maintaining blood glucose levels?
The liver
The liver plays a crucial role in glucose homeostasis during fasting.
What is the primary product of fatty acid oxidation?
Acetyl-CoA
Acetyl-CoA enters the TCA cycle for further energy production.
What is a common test for metabolic diagnosis?
- Lactate
- Glucose
- Ketones
- Uric acid
- Urea
- Ammonia
These metabolites are often measured to assess metabolic disorders.
What is the role of insulin in metabolism?
It promotes glucose uptake and storage
Insulin is a key hormone regulating blood sugar levels.
What is the main function of the TCA cycle?
To oxidize acetyl-CoA and produce energy carriers
The TCA cycle generates NADH and FADH2 for the Electron Transport Chain.
What does G6PD deficiency cause?
Episodic hemolysis and anemia under oxidative stress
G6PD is essential for producing NADPH to combat oxidative damage.
What is the end product of purine catabolism?
Uric acid
Uric acid is produced from the breakdown of purines in nucleotides.
Which metabolic pathway is only found in hepatocytes?
The urea cycle
The urea cycle converts ammonia into urea for excretion.
What are ketone bodies and when are they produced?
Acetoacetate and β-hydroxybutyrate; produced during fasting or low insulin levels
Ketones serve as an alternative energy source for some tissues, including the brain.
What indicates an inborn error of metabolism?
Pathologic variant of an enzyme
Such errors can lead to the accumulation of toxic metabolites.
What is the function of allosteric binding in metabolism?
To alter enzyme activity
Allosteric regulation can enhance or inhibit enzyme function based on metabolite availability.
What is the main source of energy for red blood cells?
Glucose
Red blood cells rely solely on glucose for ATP production as they lack mitochondria.
What is the significance of maintaining blood glucose levels?
Hypoglycemia is acutely deadly
Maintaining glucose levels is crucial for brain function and overall metabolism.
What happens to most of the fat lost from the body?
It is converted to ATP
Fat is metabolized for energy rather than leaving the body intact.
What is the role of thyroid hormone in metabolism?
It regulates metabolic rate and energy expenditure
Thyroid hormones influence various metabolic pathways.
What is the outcome of insufficient activity in a heme biosynthetic enzyme?
It can cause a porphyria due to toxic buildup of intermediates
Porphyrias are a group of disorders related to heme synthesis.
What determines whether pyruvate is converted to lactate or acetyl-CoA?
The availability of NAD+
If NAD+ is low, pyruvate is converted to lactate; if NAD+ is available, it is converted to acetyl-CoA.
