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Chapter 7:Cellular Respiration and Fermentation, - Coggle Diagram
Chapter 7:Cellular Respiration and Fermentation
Cellular Respiration
Process by which living cells obtain energy from organic molecules
Primary aim to make ATP and NADH
Aerobic respiration uses oxygen
O2 consumed and CO2 released
Primarily use glucose but other organic molecules also used
Stages of cellular respiration
Breakdown of Pyruvate
pyruvate is transported into the mitochondrial matrix
Broken down by pyruvate dehydrogenase
CO2 removed from each pyruvate
Remaining acetyl group attached to CoA to make acetyl CoA
Yield = 1 NADH for each pyruvate
Citric Acid Cycle
Metabolic cycle
Some molecules enter while others leave
Series of organic molecules regenerated in each cycle
Acetyl is removed from Acetyl CoA and attached to oxaloacetate to form citrate
Series of steps release 2 CO2, 1 ATP, 3 NADH, and 1 FADH2
the cycle happens twice therefore multiply by 2
Oxaloacetate is regenerated to start the cycle again
Glycolysis
can occur with or without oxygen
Steps identical in all living species
Ten steps in three phases
Cleavage
6 carbon molecules broken into two 3 carbon molecules of glyceraldehyde-3-phosphate
Energy liberation
Two glyceraldehyde-3-phosphate molecules broken down into two pyruvate molecules – produces 2 NADH and 4 ATP
Energy investment
2 ATP hydrolyzed to create fructose-1,6 bisphosphate
Net yield = 2 ATP
Oxidative phosphorylation
High energy electrons removed from NADH and FADH2 to make ATP
requires oxygen
involves electron transport chain
occurs by ATP synthase
inner mitochondrial membrane is relatively impermeable to H+
Protons can only pass through ATP synthase
Harnesses free energy to synthesize ATP from ADP
a rotary machine that makes ATP as it spins
Oxidation by ETC
Protein complexes and small organic molecules embedded in the inner mitochondrial membrane
Accept and donate electrons in a linear manner in a series of redox reactions
Movement of electrons generates an H+ electrochemical gradient (proton-motive force)
This provides energy for the next step –synthesizing ATP
Glucose metabolism
C6H12O6 + 6O2 → 6CO2 + 6H2O
metabolic pathways
Glycolysis
Breakdown of pyruvate
Citric acid cycle
Oxidative phosphorylation
Chemiosmosis
chemical synthesis of ATP as a result of pushing H + across a membrane
NADH oxidation makes most of the cell’s ATP
NADH oxidation creates the H+ electrochemical gradient used to synthesize ATP
Yield = up to 30-34 ATP molecules / glucose
rarely achieve maximal amount because
NADH also used in anabolic pathways
H+ gradient used for other purposes
Connections Among Carbohydrate, Protein, and Fat Metabolism
but they enter into glycolysis or citric acid cycle at different points
Utilizing the same pathways for breakdown increases efficiency
other molecules can also be used for energy: carbohydrates, proteins, fats
Metabolism can also be used to make molecules (Anabolism) chapter 4
Anaerobic Respiration and fermentation
For environments that lack oxygen or during oxygen deficient times
Two strategies
Produce ATP only via substrate-level phosphorylation
Use substance other than O2 as final electron acceptor in electron transport chain
Other acceptors like
nitrate (NO3-)
Also makes ATP via chemiosmosis even under aerobic conditions
Fermentation
breakdown of organic molecules without net oxidation
Many organisms can only use O2 as final electron acceptor, so under anaerobic conditions, they need a different way to produce ATP, like using glycolysis
Muscle cells solve problem by reducing pyruvate into lactate
But glycolysis uses up NAD+ and makes too much NADH under anaerobic conditions (dangerous situation)
Yeast solve problem by making ethanol
produces less ATP than oxidative phosphorylation