Everyone knows that energy is essential for sustaining life. How can you define energy in life? Have ever thought about ways of how carbohydrates like glucose from your diet can be used for extracting energy? A scientific field that focuses on energy production and flow though living cells and organisms is called bioenergetics. Energy metabolism covers various biochemical ways of energy transformation and regulatory mechanisms of over thousands chemical reactions. Without fine control of those metabolic processes, cells and organisms cannot maintain activities linked to life. This 7 week-course will give you a clear introduction to the basic fundamentals of energy metabolism. We will first establish the concept of energy metabolism and subsequently examine biochemical steps involved in energy production from glucose oxdiation as well as glucose synthesis via photosynthesis. We will also learn about metabolic reactions related to fat as well as regulatory actions among different organs. Finally, dysregulated energy metabolism in pathological conditions such as diabetes and cancer will be discussed. Everyone knows that energy is essential for sustaining life. How can you define energy in life? Have ever thought about ways of how carbohydrates like glucose from your diet can be used for extracting energy? A scientific field that focuses on energy production and flow though living cells and organisms is called bioenergetics. Energy metabolism covers various biochemical ways of energy transformation and regulation of thousands of chemical reactions. Without fine regulation of those metabolic processes, cells and organisms cannot maintain activities linked to life. This 7 week-course will give you a clear introduction to the basic fundamentals of energy metabolism. We will first establish the concept of energy metabolism and subsequently examine biochemical processes involved in energy production as well as photosynthesis. We will also learn about metabolic reactions related to fa as well as regulatory actions among different organs. Finally, dysregulated energy metabolism in pathological conditions such as diabetes and cancer will be discussed.
1. Metabolic responses to starvation
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Do curso por Korea Advanced Institute of Science and Technology
Biochemical Principles of Energy Metabolism
19 classificações
Korea Advanced Institute of Science and Technology
19 classificações
Na lição
Module 7: Energy Homeostasis in your body
Conheça os instrutores
Seyun KimAssistant Professor
Department of Biological Sciences
[MUSIC]
>> Hello, everyone.
Welcome back to my Coursera class,
Biochemical Principles of Energy Metabolism.
So this is week seven, the final week of this class.
So I'm going to introduce six different topics.
So in the beginning, it's about metabolic response to starvation condition and
the second one is about stress hormone dependent metabolic action.
And the third one is about biochemical events
taking place in response to exercise.
And with four, it's about ethanol metabolism.
What is the metabolic consequences after the ethanol alcohol consumption and
the session five is about cancer cell specific energy metabolism.
And finally, session seven includes the importance of gut microbiota and
their actions in the regulation of bioenergetics.
Let me begin with the changes of biofuels during starvation in the first session.
That's what first session is about starvation dependent metabolic processes.
So we're looking at plasma levels on the Y-axis and
the days of starvation on the X-axis.
So as I explained, glucose is the primary vital
nutrient energy source for many peripheral cells and tissues.
So like brain and heart muscle cells.
So in the very beginning around six millimolar glucose maintain and
it is gradually reduced across the, a chronic starvation situation.
And when the carbohydrate consumption is significantly reduced
across the starvation even though many metabolic systems
are trying to back up and trying to maintain blood glucose level
at reasonable amount of levels, but it is very demanding.
So instead, fats are degraded from adipose tissue and they are released.
So fatty acids levels are gradually increased,
because fatty acids are readily available a second class nutrients.
So they are degraded from adipose stored triacid glycerols and released.
And on top of those two glucose and fatty acids, very interestingly,
the third class of biofuels are coming up.
They are called ketone body.
A collection of very unique biochemical metabolites.
So ketone bodies are produced and
then are released into circulatory system.
So the main concept of this first session is about ketone body formation.
So what is ketone body?
So ketone bodies are very interesting metabolic products and
these ketone bodies produced from fatty acid beta-oxidation in the very beginning.
But ultimately, they are produced through the ketogenic biochemical
enzymatic reactions and this ketogenesis occurs in the liver.
So hepatocyte synthesize ketone bodies out of fatty acids.
So ketone bodies become very, very important fuel sources in particular for
brain and hearts in response to chronic starvation condition.
And secondly, again, the liver cells can break down amino acids,
protein breakdown so-called proteolysis and
those amino acids are utilized to drive gluconeogenesis.
So many amino acids can be catabolized into metabolic
intermediates essential for gluconeogenesis to produce and
then release glucose from the liver cells to the system.
And ultimately, peripheral tissues.
So ketone bodies and ketogenesis.
So there are three types of ketone bodies available,
acetoacetate, beta-hydroxybutyrate and acetone.
Again, they are produced from the liver by using the fatty
acids as substrate under the chronic starvation condition
as well as medical situations like the diabetis mellitus.
And those ketone bodies are utilized by other tissues,
in particular brain and heart and muscle cells.
They are very ready to utilize ketone bodies to drive our ATP synthesis.
So two molecules of acetyl-CoA.
Those acetyl-CoA can be produced from fatty acid of beta oxidation and
they are condensed and then more acetyl-CoA required.
And finally, the intermediate
beta-hydroxy-beta-methylglutaryl-CoA enzyme and
they can be split into acetate or acetone and hydroxybutyrate.
In particular, acetone, this molecule is not required for
a further energy ATP synthesis.
Simply it's created in the urine.
However, those two, acetoacetate and beta-hydroxybutyrate.
Once they are released from liver cells throughout this ketogenic
metabolic reaction.
And finally, imported into our brain cells and heart cells and
they are being utilized to synthesize acetyl-CoA back to acetyl-CoA.
And those acetyl-CoA are fully oxidized throughout
the chronic acetyl cycle and acetyl-phospho formation.
That is the ketogenesis.
So in particular in the context of ketogenesis, I want to emphasize
the importance of medical condition called the diabetic ketoacidosis.
So this is very detrimental situation like life-threatening
complication caused from the diabetes.
So this situation means like extremely high levels of
ketone bodies produced and detected in the diabetic patient.
So situations like this.
So in the absence of insulin or under the insulin resistance situation.
So liver cells cannot efficiently uptake glucose and
rather release glucose through the gluconeogenesis.
And in particular, so one of key intermediates for
gluconeogenesis is oxaloacetate.
And oxaloacetate is also very important to drive the TCA cycle in the mitochondria.
So the situation's like this.
So under the huge or active fatty acid degradation in
the liver from the diabetic patient.
I mean, the more like the terminal stage of diabetic patient.
So acetyl-CoA levels will be increased.
But the thing is because of the depletion of oxaloacetates within the liver,
acetyl-CoA cannot be used to going to the TCA cycle and
rather this acetyl-CoA are used for
massive ketogenic programs like ketogenesis.
So finally, those of ketone bodies are released into
the circulatory system and blood pH rapidly drops.
So acidosis become acidic, because the ketone bodies are acids.
So because of this, a huge amount of ketone bodies.
So finally, patient can undergo coma and
more like death if appropriately untreated.
So this is one of the important aspects of ketogenesis,
regulation of ketogenesis, in particular in the context of diabetes.
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