Lecture 7 Flashcards
definition of metabolism, what it utilizes and creates
Series of chemical reactions to sustain and promote life :
- utilizes 4 main building blocks (macromolecules)
- catabolism into smaller molecules -> releases energy (ATP)
- anabolism to form the needed molecules -> requires energy
whar catalyzes metabolic pathways ?
specific enzymes !
structure of adenosine triphosphate
adenine + ribose + 3 phosphate groups (4 oxygens attached)
ATP hydrolysis : reaction equation, role of ATPase (in energy profile)
ATP + H2O -> ADP + POH + H+
Water does a nucleophilic attack on the last phosphate group. The ATPase (+ charges) keeps the - charges of the oxygens busy while water attacks.
This brings the activation energy down and allows reaction to happen.
cellular respiration : chemical reaction, name the 4 steps
glucose + 6O2 -> 6CO2 + 6H2O + energy (heat + 38 ATP)
1) glycolysis
2) pyruvate oxydation
3) krebs cycle (citric acid cycle)
4) oxydative phosphorylation (electron chain)
where do the 4 steps of the respiration happen ?
glycolysis -> cytosol
2 and 3 -> in mitochondrial matrix
4 -> on mitochondrial membrane
name two electron carriers
NAD+ -> NADH
FAD -> FADH2
glycolysis : two phases, intermediate step, net balance
1) investement phase : we use 2 ATP for 1 glucose
-> 2 molecules P-GAL (3 C each)
2) Payout phase : 2x 2ATP and NADH released, 2 pyruvates formed
glucose + 2NAD+ -> 2 pyruvates + 2ATP + 2NADH
pyruvate oxydation : what happens ? net balance
Pyruvate is cut in two -> first part is CO2 and second side binds to CoA to form acetyl-CoA.
1 pyruvate -> CO2 + NADH + acetyl-CoA (2 carbons)
krebs cycle : name the two molecules in the cycle, net balance, how many ATP from NADH and FADH2 ?
citric acid (6 carbons)
oxaloacetic acid (4 carbons)
net result : 4 ATP, 10 NADH, 2 FADH2
1 NADH -> 3 ATP
1 FADH2 -> 2 ATP
what happens in the electron transport chain ?
NADH and FADH2 bring electrons into protein complex -> electrons push protons out in intermembrane space -> electrochemical gradient -> protons go through complex V which drives ATP synthesis
how is the respiration pathway controlled ?
whatever molecule from downstream will inhibit pathway, and molecules from upstream are activators.
Ex : if too much ATP, process is slowed down
where do carbohydrates enter the cellular respiration pathway ?
ex : glycogen is degraded into glucose - 6 - phosphate, which enters in the first step (glycolysis)
proteins entering the pathway : first step in humans, what determines where they enter ?
First, amino group is removed (NH3), converted into urea and excreted in urine.
Chemical properties of each amino acid determines which intermediate they can be most easily converted into -> enter either in pyruvate, acetyl-CoA, or krebs cycle.
how do lipids enter the pathway ?
trigylcerides are broken into P-GAL (head of fat) and the long tail is broken every two carbons -> form Ac-CoA.
P-GAL -> glycolysis
Ac-CoA -> 3rd step
