Class 2- Fuel Metabolism Flashcards
What are the 3 dietary fuel sources?
Glucose, Fatty acids, amino acids
How to dietary fuels form ATP?
Glucose, fatty acids and amino acids loose an electron and Acetyl CoA is used to catalyze the TCA/Krebs Cycle which produces C02. Then the electron transport chain outputs ATP and H20 from O2 molecules.
What are the ways that cells use energy to do work?
Make things (synthetic work), move things like in transport (mechanical work), gather and force things like concentration gradients (concentration/electrical work), heat things like muscles when cold (thermal work)
What is true for Biochemistry but not in Chemistry about breaking bonds and energy?
In biochemistry we imprecisely say that breaking bonds releases energy. ===Breaking bond between 2 and 3rd phosphate groups of ATP releases energy that can be used to do cellular work===In chemistry we say breaking bonds requires energy
What is the total quantity of ATP in the body? What is the turn over?
There is 0.10 mol/L of ATP in the body. There is a lot of turn over in the body so levels seem low because it is being used so much
How much ATP is required each day?
100-150 mol/L of ATP are required daily which means that each ATP molecule is recycles 1000 to 1500 times per day. The human body turns over its own weight in ATP daily!
What is the structure of ATP?
RNA molecule with 3 phosphates (5 carbon sugar ribose, nitrogenous adenine base). ATP is made unstable by the three adjacent negative charges in its phosphate tail, which “want” very badly to get further away from each other. The bonds between the phosphate groups are called phosphoanhydride bonds, and you may hear them referred to as “high-energy” bonds.
Why are the phosphoanhydride bonds considered high-energy? How is ATP broken down?
ATP is broken during a hydrolysis (water-mediated breakdown) in a REVERSIBLE reaction. Breaking bonds to form ADP from ATP releases energy and converting ADP + pi to ATP requires energy
What is ATP used for versus ADP?
ATP: energy utilization (biosynthesis, detoxification, muscle contraction, active ion transport, thermogenesis)
ADP: energy production via oxidation of carbohydrates, lipids, proteins which releases O2, H20, Heat
Why is the regeneration of ATP important (ADP + Pi ==> ATP using energy)
Regeneration of ATP is important because cells tend to use up (hydrolyze) ATP molecules very quickly and rely on replacement ATP being constantly produced
How does ATP and ADP reflect energy consumption?
You can think of ATP and ADP as being sort of like the charged and uncharged forms of a rechargeable battery (as shown above). ATP, the charged battery, has energy that can be used to power cellular reactions. Once the energy has been used up, the uncharged battery (ADP) must be recharged before it can again be used as a power source. The ATP regeneration reaction is just the reverse of the hydrolysis reaction:
How is the energy released by ATP hydrolysis used to power other reactions in a cell?
In most cases, cells use a strategy called reaction coupling, in which an energetically favorable reaction (like ATP hydrolysis) is directly linked with an energetically unfavorable (endergonic) reaction. The linking often happens through a shared intermediate, meaning that a product of one reaction is “picked up” and used as a reactant in the second reaction.
When ATP is hydrolyzed (bond between second and third phosphate is broken) then energy is released because..
because the products of the reaction (ADP + phosphate) are more stable with lower bond energies than the reactants (ATP and water)
Why are the phosphoanhydride bonds in ATP so unstable?
their negative charged phosphate groups repel eachother and strain the bonds between them
How can ATP hydrolysis be coupled to other classes of cellular reactions? such as the shape changes of proteins that transport other molecules into or out of the cell.
t’s energetically unfavorable to move sodium (Na+) into, a typical cell, because this movement is against the concentration gradients of the ions. ATP provides energy for the transport of sodium and potassium by way of a membrane-embedded protein called the sodium-potassium pump (Na+/K+ pump).
How does glucose stimulate beta cells to release insulin?
- glucose goes through glycolysis, TCA cycle, oxidative phosphorylation which produces ATP
- There is an inhibition of K+ and K+ pumps close which decreases membrane potential
- This stimulates calcium channels to open to let calcium into the cell
- This triggers the release of insulin from the cell by exocytosis
How is the insulin receptor activated by insulin? What kind of receptor?
Receptor tyrosine with extra and intracellular components has insulin bind and forms active conformation
How does insulin target cells to take up glucose?
- insulin binds
- tyrosine receptor activated
- signaling molecules tell GLUT4 receptors not at the cell surface to translocate to surface
- glucose is taken into the cell
- glucose used for metabolism - glycolysis (ATP + pyruvate) and lipogenesis (lipids) – or storage (glycogenesis) to make glycogen
Storage: What is glycogenesis?
formation of glycogen from glucose (this happens in the liver when glucose levels are high after they are uptake into the cell when insulin triggers the receptors to the surface)
How is glucose used in adipose tissues and muscles?
glucose forms triglycerides in adipose tissue (connective tissue) and uses Acetyl CoA –> TCA cycle –> Co2 and ATP
How is glucose used in adipose tissues and muscles?
glucose forms triglycerides in adipose tissue (connective tissue) and uses Acetyl CoA –> TCA cycle –> Co2 and ATP
