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Chapter 7 Cellular respiration, 4)Oxidative Phosphorylation, 3)Citric…
Chapter 7
Cellular respiration
The way cell obtain energy from organic molecules
uses glucose primarly + O2
1)glycolysis
3 phases and 10 steps
Cleavage (4-5)
Energy liberation (6-10)
in Cytosol
2)Breakdown of Pyruvate
Pyruvate enter mitochondrial matrix
Enter by:
channel in outer membrane
H+/pyruvate symporter in inner membrane
Pyruvate (via pyruvate dehydrogenase) ---------> acetyl group(transferred later to acetyl CoA)+co2
For 1 Glucose:
Use: 2 pyruvates
produce: 2 NADH
in: mitochondrial matrix.
carbohydrates, proteins and fats can be used.
enters: into step 1 or 3.
If environment Lacks O2:
Two strategies:
2)Fermentation
Make ATP via substrate-level phosphorylation only.
Problem: make a lot of NADH under anaerobic conditions (dangerous).
Solution:
Muscle cell: reduce pyruvate to lactate
Yeast: making ethanol.
breakdown of organic molecules.
Produce: 2ATP
Less than oxidative phosphorylation.
1)Anaerobic respiration
In ETC:
instead of using O2 as final e- acceptor.
use other substance
EXP: E.coli uses NO3-.
4)Oxidative Phosphorylation
make ATP by removing high energy electrons from: NADH, FADH2. (ETC)---> result in H+ electrochemical gradient.
NEED 02
Occur by: ATP synthase (a rotary machine= make ATP as it spin)
H+ move down its concentration gradient through it (because innner mitochondrial membrane is impermeable to H+)
Convert energy
from motive force of H+ gradient------> chemical bond in ATP
accepting and donating e- is a series of: Redox reactions.
in: mitochondria inner membrane.
on slide 17/all pump H+ into intermembrane space except: Succinate reductase, Ubiquinone and Cytochrome C.
NADH oxidation
Yield: 30-34 ATP
rarely achive maximal amount because:
anabolic pathways uses NADH
H+ gradient used for other perposes.
3)Citric Acid Cycle (Kerbs cycle)
Acetyl from acetyl CoA+ oxaloacetate -------> citrate.
oxaloacetate regenerated to enter the cycle again.
For 1 Glucose:
2 acetyl CoA enter
produce: 2 ATP, 2 FADH2, 4CO2, 6NADH
in: mitochondrial matrix
Energy investment (steps1-3)
Use 2ATP
Produce: 4ATP, 2NADH
NET yield: 2ATP
Glucose ------ 2Pyruvates ------- 2-----