BCH 403 Exam 2-Questions With 100% Verified
Answers.
What are the functions of the 3 subunits of the PDH complex? - ✔✔E1 and E2
convert pyruvate into Acetyl-CoA
E3 specifically resets the coenzymes
What happens during decarboxylation in the PDH mechanism? - ✔✔TPP in E1
deprotonates and the now negative carbon attacks the carbon in pyruvate this causes a cleavage
event on pyruvate and leaves a 2 carbon group attached to the TPP
What happens during the Reduction and Transacetylation step in the PDH mechanism? -
✔✔The carbanion attacks the disulfide bond in lipoamide (LA) causing a cleavage event
that regenerates TPP and leaves the 2 carbon group bound to LA
What happens during the repositioning step in the PDH mechanism? - ✔✔The arms of
LA reposition the 2 carbon group in order to get in proper orientation for the next step
What happens during transthiolation step in the PDH mechanism? - ✔✔The free floating CoA
cleaves the acetyl off of the lipoamide forming the product Acetyl-CoA and leaves one of the
LA arms protonated - which needs to be in the disulfide bond state
What happens during the re-oxidation step of the PDH mechanism? - ✔✔The long
swinging arms of LA come down to E3/FAD to become oxidized and regenerated the FAD
prosthetic groups becomes reduced
, What happens during reoxidation of FAD in the PDH complex? - ✔✔The free floating NAD
enzyme oxidizes the FAD regenerating the PDH complex allowing the next cycle to begin
What are the 2 floating enzymes in the PDH mechanism? - ✔✔NAD+ and CoA
What are the prosthetic groups in the PDH mechanism? - ✔✔TPP (bound to E1)
LA (bound to E2)
FAD (bound to E3)
What are major components of biological membranes? - ✔✔Phospholipid Bilayer,
Proteins (glycoproteins, integral membrane protein, peripheral membrane protein)
carbohydrates
What is a lipid? - ✔✔Any substance that is soluble in a non-polar solvent and is essentially
insoluble in water
What is the major characteristic of BIOLOGICAL lipids? - ✔✔Largely hydrophobic
and amphipathic
Hydrophilic head and hydrophobic tail that have different properties
What does this fatty acid nomenclature explain?
18:2∆9,12 - ✔✔18 total carbons
2 double bonds in the hydrocarbon tail
9 and 12 are the positions of the double bond starting with Carbon 1 being closest to
the hydrophilic reason
What is a key point in the number of Carbons in a hydrophobic tail? - ✔✔There is always
an even number of Carbons - enzymes that make fatty acids add carbons on 2 at a time
Answers.
What are the functions of the 3 subunits of the PDH complex? - ✔✔E1 and E2
convert pyruvate into Acetyl-CoA
E3 specifically resets the coenzymes
What happens during decarboxylation in the PDH mechanism? - ✔✔TPP in E1
deprotonates and the now negative carbon attacks the carbon in pyruvate this causes a cleavage
event on pyruvate and leaves a 2 carbon group attached to the TPP
What happens during the Reduction and Transacetylation step in the PDH mechanism? -
✔✔The carbanion attacks the disulfide bond in lipoamide (LA) causing a cleavage event
that regenerates TPP and leaves the 2 carbon group bound to LA
What happens during the repositioning step in the PDH mechanism? - ✔✔The arms of
LA reposition the 2 carbon group in order to get in proper orientation for the next step
What happens during transthiolation step in the PDH mechanism? - ✔✔The free floating CoA
cleaves the acetyl off of the lipoamide forming the product Acetyl-CoA and leaves one of the
LA arms protonated - which needs to be in the disulfide bond state
What happens during the re-oxidation step of the PDH mechanism? - ✔✔The long
swinging arms of LA come down to E3/FAD to become oxidized and regenerated the FAD
prosthetic groups becomes reduced
, What happens during reoxidation of FAD in the PDH complex? - ✔✔The free floating NAD
enzyme oxidizes the FAD regenerating the PDH complex allowing the next cycle to begin
What are the 2 floating enzymes in the PDH mechanism? - ✔✔NAD+ and CoA
What are the prosthetic groups in the PDH mechanism? - ✔✔TPP (bound to E1)
LA (bound to E2)
FAD (bound to E3)
What are major components of biological membranes? - ✔✔Phospholipid Bilayer,
Proteins (glycoproteins, integral membrane protein, peripheral membrane protein)
carbohydrates
What is a lipid? - ✔✔Any substance that is soluble in a non-polar solvent and is essentially
insoluble in water
What is the major characteristic of BIOLOGICAL lipids? - ✔✔Largely hydrophobic
and amphipathic
Hydrophilic head and hydrophobic tail that have different properties
What does this fatty acid nomenclature explain?
18:2∆9,12 - ✔✔18 total carbons
2 double bonds in the hydrocarbon tail
9 and 12 are the positions of the double bond starting with Carbon 1 being closest to
the hydrophilic reason
What is a key point in the number of Carbons in a hydrophobic tail? - ✔✔There is always
an even number of Carbons - enzymes that make fatty acids add carbons on 2 at a time
