Metabolism Flashcards
Lec 29-39 (20 cards)
What energy sources does long term exercise primarily use?
Fatty acids and glycogen
What is the role of UCP1 in thermogenesis?
UCP1 (Uncoupling Protein 1), found in the inner mitochondrial membrane of brown adipose tissue (BAT), plays a critical role in thermogenesis. Instead of ATP production, UCP1 allows H+ ions to flow back into the mitochondrial matrix without passing through ATP synthase, thus uncoupling the electron transport chain from oxidative phosphorylation. This process dissipates the proton gradient as heat. Activation of UCP1 is stimulated by fatty acids, which are released in response to hormonal signals (e.g., norepinephrine) when the body needs to increase heat production
How is CREB activated and what does it do?
Activated by PKA, CREB binds to a transcription element to alter gene expression
How does adipose tissue creation affect fatty acid absorption?
Adipose tissue facilitates fatty acid (FA) absorption and storage, primarily as triacylglycerols (TGs). When fatty acids enter adipocytes, they are converted into TGs through a process called esterification. This process involves the attachment of fatty acids to a glycerol backbone, forming a neutral fat molecule. The increased synthesis and storage of TGs in adipose tissue serve as an efficient way to store energy, as TGs are energy-dense and can be mobilized during periods of energy demand. Hormones like insulin promote FA uptake and TG synthesis in adipocytes, while other hormones such as epinephrine stimulate the breakdown of TGs (lipolysis) to release fatty acids
What are the Km characteristics of GLUT1, GLUT3, and GLUT2 transporters?
GLUT1 and GLUT3 have low Km, while GLUT2 has a high Km
Which glucose transporters are insulin responsive?
GLUT4 and HKII
What promotes gluconeogenesis in the liver during fasting?
Cortisol and glycogen
Which hormone is released when glucose continues to drop and what subsequent actions occur?
Adrenaline targets the liver, which then uses glycerol and fatty acids
Why are keto bodies used during starvation?
Reduce glucose requirement
How does adrenaline affect perilipin and the TG droplet?
Adrenaline phosphorylates perilipin coating, uncovering the TG droplet
How does insulin affect PFK2 activity?
Insulin dephosphorylates F-6-P to PFK2, activating it
What stimulates pyruvate dehydrogenase?
ADP and AMP
How does insulin stimulate glycogenesis?
Insulin activates phosphoprotein phosphatases to remove phosphates from GSB to GSA
Name four hormones that contribute to gluconeogenesis.
Glucagon, cortisol, thyroid hormone, and growth hormone
What activates the G-coupled receptor?
GTP
Besides glycerol and AA, what is another non-carbohydrate molecule used for making glucose?
Lactic acid
Which enzyme controls the conversion of pyruvate to oxaloacetate?
Pyruvate carboxylase
What enzyme removes phosphate to remain glucose?
Glucose-6-phosphatase
What enzyme catalyzes the reaction of ammonium with CO2?
Carbamoyl phosphate synthetase 1
