Lecture 6 Cellular Metabolism Flashcards
Glucose
high energy molecule that we start with
primary substrate(monomer) for cellular respiration
required by brain and CNS
ATP
the energy currency molecule
energy contained in phosphate group
Pyruvate
end product of glycolysis
branch point between aerobic and anaerobic metabolism
glucose split into two = pyruvate
Lactate
end product of anaerobic metabolism
Acetyl CoA
the 2 carbon shuttle
a key intermediate in aerobic metabolism
NAD+
oxidized coenzyme (also FAD) lost its electrons, low energy form
NADH
reduced coenzyme (also FADH2) carrier of 2 high energy electrons
O2
the final electron acceptor in aerobic metabolism
CO2
end product of aerobic metabolism
H20
other end product of aerobic metabolism
Oxidation of glucose
glucose + 6 02 –> 6CO2 + 6H20 + energy ->ATP,Heat
Cellular respiration
metabolism of substrates to release energy to form ATP
Hexokinase
adds phosphate group to glucose
phosphofructokinase
adds phosphate to fructose making it have 2 phosphates major regulatory enzyme
Glycolysis
partial breakdown of glucose to pyruvate. glucose -> 2 pyruvate
occurs in cytosol
multi step pathway
Energy investment step in glycolysis
adds 2 high energy phosphates from ATP
input 2 ATP
Cleavage step in glycolysis
splits 6C sugar into two 3C molecules
Energy capture step in glycolysis
yield 2 NADH and 2 ATP
NADH in glycolysis
each carries two high energy electrons
NAD+ + 2H (oxidized) –> NADH + H+ (reduced)
Aerobic metabolism
pyruvate goes to transition step and then CAC in the mitochondria
NADH donates electrons to the ETC
Requires oxygen
Glycolysis aerobic metabolism net yield and product
yield: 2 ATP and 2 NADH per glucose
Product: 2 Pyruvate
Anaerobic metabolism
pyruvate is converted to lactate via the lactic acid pathway in the cytosol
NADH is converted back to NAD+ needed to continue glycolysis
oxygen is being reduced while NADH is being oxidized
Glycolysis anaerobic metabolism net yield and product
Yield: 2 ATP per glucose
Product: 2 lactate + 2H+
Transition step form glycolysis to the Citric Acid Cycle
yield: 1 NADH
product: 1 CO2
acetyl CoA is a key intermediate which transfers 2C units to the Citric Acid Cycle
Citric Acid Cycle
occurs in matrix of mitochondria
First step: 2C unit from acetyl CoA combines w/ oxaloacetate(4C) to form citrate (6C)
Second Step: citrate is oxidized back to oxaloacetate
2 Carbon atoms are fully oxidized to form 2 CO2 molecules
Net yield and product of Citric Acid Cycle
yield: 3 NADH + 1 FADH2 + 1 ATP
Product: 2 CO2
Electrons in the Citric Acid Cycle
high energy electrons are transferred to NADH and FADH2 and carried to the ETC
ETC
electron carrier proteins are located in the INNER membrane of the mitochondria
3 major protein complexes (1,3,4)
NADH and FADH2 donate high enery electrons to the ETC
electrons move downhill through ETC release energy for ATP production
02 is the final electron acceptor
cytochromes
iron-containing proteins in the ETC
ATP synthesis
flow of H+
Chemiostatic coupling mechanism:
ETC complexes act as H+ pumps
H+ is pumped uphill from the matrix into the intermembrane space containing high [H+]
H+ moves back downhill through the ATP synthase in the inner membrane
ATP synthase phosphorylates ADP to ATP
Complete oxidation of glucose yield and product
yield: about 30 ATP per glucose
End product: 6 CO2 + 6 H20
