Download RESPIRATION Production of ATP and CO2 by O2 and organic

RESPIRATION
Production of ATP and CO2 by O2 and organic molecules delivered through bloodstream
Living is work
E = capacity to do work
Two characteristics of living things:
- Use of E
- Organization
E required for these 2 characteristics comes from sun E captured in Photosynthesis
Autotrophs (Gr. Self feed) perform Photosynthesis
Heterotrophs (Gr. Other feed) rely on Autotrophic production
Metabolism: sum of reactions taking place in cells
Anabolism: building of larger molecules using E
Catabolism: breaking down larger molecules and releasing E
Aerobic: in the presence of O2, ½ O2 is final e- acceptor
Anaerobic: in the absence of O2
Oxidation: removal of eReduction: addition of eC6H12O6 +6O2  6CO2 + 6H2O + E (ATP + Heat)
This is typically how Respiration (and Photosynthesis) is represented
Oxidation of sugar, Reduction of molecular oxygen
But is a much simplified representation
“The process is complex and challenging to learn.”
The objective is an understanding of how cells use E stored in food to make ATP
ATP is a loaded spring (potential chemical E)
Release of this spring often results in Phosphorylation of compounds
ATP is generated in Respiration
Through a series of Oxidation – Reduction Reactions of large Organic Molecules
Aka redox
Occurs as organized Covalent C – H bonds are oxidized and their E captured
These bonds represent the “hilltop” as Respiration proceeds “downhill”
Toward very electronegative ½ O2
Respiration takes the E out of storage in these Covalent Bonds
In sugar, starch, glycogen, fat, protein
NAD+ is Respiratory Electron Carrier
Reduced NADH results from addition of 2 e- and 1 H+
Contains nearly all the energy from the original organic molecule bond
Key: Ea keeps us from burning up
Without it, all these reactions would occur spontaneously
Exergonic, releases E, negative delta G
Consider burning a tank of gas all at once
e- carriers and stepwise oxidation capture this E in an organized fashion
Remember organization requires E
Respiration has Three Major Steps
1) Glycolysis
In cytoplasm
Breaking Organic Molecule into 2 3-Carbon Pyruvate molecules
Produces 2 NADH and 2 ATP
This is NET; Remember Ea, Costs 2 ATP to overcome and 4 ATP formed
NO CO2 released
2a) Prep Reaction carries Pyruvate into Mitochondrion, oxidized to Acetyl CoA
ACoA is an Unstable Two Carbon Compound
CO2 is released
Happens Twice because Two Pyruvates produced
2)
Krebs Cycle (Hans Krebs, 1930’s)
Occurs in Mitochondrial Matrix
Aka TCA Cycle, Citric Acid Cycle
Occurs Twice, Once for each AcoA produced above
Produces 2 CO2, 3 NADH, 1 FADH2, 1 ATP
PER CYCLE
Substrate Level Phosphorylation
Direct formation of ATP by transfer of P group from intermediate substrat
3) Electron Transport Chain
Occurs on Cristae
Pair of High E e- from NADH are carried “downhill” through path in Redox
Produces 5 ATP
3 from NADH
2 from FADH2
Because it enters chain “lower”
Oxidative Phosphorylation: ATP production in presence of O2
O2 as terminal e- acceptor:
e- from 2 NADH reduce 1 O2 to 2H2O
Chemiosmosis
Production of Steep Electrochemical Gradient with Proton Pump
H+ produced during e- Transport are moved from inner membrane of cristae
To intermembrane space, creating gradient
Produces bulk of Aerobic Respiration ATP
So, anaerobic respiration not nearly as efficient
ATP Bookkeeping: bear in mind that these are rounded figures
39% efficiency
yea! That’s Aerobic Respiration
Fermentation
Anaerobic respiration
Pyruvate from Glycolysis
Oxygen debt, can’t remove lactate as fast as it’s produced, delta pH
2% efficiency
Other Respiratory Substrates
Glucose was our example
Fat  Glycerol + 3 Fatty Acids
Glycerol (3 C cmpd) can enter Glycolysis
FA can be broken down into ACoA and enter Krebs Cycle
Proteins can be catabolized and enter Respiration at various points
Must be broken down into AA, and then deaminated
Amine (N) group removed
Anabolism
Respiratory substrates and products can be used to form Macromolecules
Glycerol  fat
Amino acids  protein
(Essential AA cannot be produced by humans)