Biochemistry week 11 Flashcards
What is carbohydrate and lipid oxidized to generate
- ATP
What is the primary energy carrier
ATP
Where does most energy production occurs through
Redox reactions in the mitochondria
What is ATP synthesis tightly coupled with
respiration
What does Gibbs free energy measure
- It measures the maximum energy obtainable from a reaction at constant temperature and pressure
What type of reactions produce ATP
Catabolic reactions
What is the structure of ATP
- Contains Adenine (base), ribose sugar, 3 phosphate groups
What is the name of the bonds between the phosphate groups
Phosphoanhydride bons
Name some common uses of ATP
- Active transport
-Biosynthetic reactions
What is the primary function of Mitochondria
Essential for aerobic metabolism
Where does glycolysis occur
- Cytoplasm
Where does fatty Acid oxidation and ATP production take place
- Mitochondria
What is the energy from the oxidation of reduced coenzymes used for
- To synthesize ATP through oxidative phosphorylation
What are the characteristics of the Outer mitochondrial membrane
- Contains enzymes and transport proteins
-Permeable to ions,small molecules and proteins
What are the characteristics of the Inner Mitochondrial Membrane
- Impermeable to most ioms and small molecules
-Contains transporters for selective molecule translocation
Where is the electron Transport chain embedded
- It is embedded in the inner mitochondrial membrane
What are the components of the ETC(what it includes)
It includes large protein complexes + 2 smaller components:
-Ubiquinone (co enzyme Q)
-Cytochrome C
Explain the mechanism of electron transfer
- Electrons move through a sequence of redox reactions
- The flow is the from molecules with negative reduction potentials to those with positive reduction potentials
Where are electrons donate from in the ETC
- By reduced nucleotide enzymes
What is the final electron acceptor
- where oxygen acts as the terminal electron acceptor, combining i=with electrons to form water
How does electrons loose energy in the ETC
- They loose energy at each step of the way
What drives proton transport
- Energy released from electron transfer drives proton transprt from the mitochondrial matrox to inermembrane space
What is involved in creating a proton gradient
- 3 proton pumps
What is the purpose of a proton gradient
- The gradient powers ATP synthesis in oxidative phosphorylation
What is the purpose of Electron shuttles
They allow the oxidation of cytosolic NADH without the physical transfer into the mitochondrion
Name 2 types of electron shuttles
-Glycerol -3-phosphate shuttle
-Malate - Aspartate shuttle
What is the mechanism of the glycerol -3-phosphate mechanism
-NADH reduces DHAP to G3P in the cytosol
-G3P is oxidized back to DHAP at the mitochondrial membrane, transferring electrons to FAD to form FADH2
- Elextrons enter the ETC via ubiquinone
What is a common use of the glycerol-3-phosphate shuttle
In skeletal muscles
What are common uses of the Malate-Aspartate shuttle
Heart and liver
Explain the mechanism for Malate-Aspartat shuttle
- Oxaloacetate is reduced to malate in the cytoplsm
-Malate crosses the inner mitochondrial membrane and it is reoxidized to oxaloacetate in the mitochondria
What is ATP synthesis in the mitochondria driven by
- The proton gradient during the oxidation of NADH and FADH2
Name the 3 major coenzymes
- NAD +
-FAD
-FMN
How are the 3 major coenzymes reduced
- Electrons are transferred from carbohydrates and fat reducing them
What is the reduced form of the 3 Major coenzymes
- NADH
-FADH2
FMNH2
What does NAD+ accept when being reduced
- Hydride ion with 1 proton and 2 electrons
What does FAD and FMN accept when being reduced
- 2 electrons and 2 protons
Name the 4 protein complexes that the ETC contains
complex 1 -NADH dehydrogenase
complex 2 - Succinate dehydrogenase
complex 3-cytochrome bc1
complex 4 -cytochrome C oxidase
What is the function of complex 1 (NADH dehydrogenase)
-Accepts electrons from NADH and trasfers them to FMN and to coQ
- Pumps 4 H+ (protons) into the intermembrane space
What is the function of the complex 2 (succinate dehydrogenase)
- Trasnfers electrons from FADH2, then to coA
What is the function of complex 3(cytochrom bc1)
Transfers electrons from coQ to cytochrome C
-Pumps 4 protons (H+ ions) across the inner mitochondrial membrane
What is the function of complex 4 (cytochrome c oxidase)
- Reduces oxygen to water using electrons from cytochrome c
- Pumps 2 H+ ions across the membrane
Explain the structure of ATP synthase and functions
- Composed of 2 domains
-F0 domain: forms an H+ channel
-F1 domain: Where ATP sythesis occurs
Explain how protons are pumped and what it creates
- The protons are pumped from the mitochondrial matrix to the intermembrane space at complexes 1,3,4. This creates:
-An electrical gradient
-A pH gradient
These combined drive ATP synthesis
Explain the process of ATP synthesis
-The H+ ions flow back into the matrix through the F0 channel
-This drives the rotation of the c-ring in the F0 domain
- Rotation causes a conformational change in the 3 beta subunits of the F1 domain , enabling:
-binding of ADP + pi
-Phosphorylation of ADP to ATP
-
What are the effects of uncouplers
- Increased respiration and heat productiom
Name 2 types of uncouplers
- uncoupling protein-1
-2,4 dinitrophenol
What is the function of uncouplers
- Distrupt the proton gradient by transporting proton back into the mitochondria wihtout passing through ATP synthease
