Cellular Respiration and Fermentation Chap 7

Fermentation

a catabolic process that is the partial degradation of sugars/organic fuel without the use of oxygen

Aerobic respiration

catabolic pathway that’s most efficient, consumption of organic fuel and oxygen

Anaerobic respiration

prokaryotes use not oxygen to harvest chemical energy

Organ compounds + Oxygen → Co2 + H2O + energy

aerobic respiration

Redox Reactions

electron transfers from one reactant to another (oxidation reduction reactions)

Loss of electrons from one substance to another

oxidation

Addition of electrons to another substance 

reduction

From the formula Na + Cl to Na+ + Cl- what becomes oxidized

the Na to Na+

From the formula Na + Cl to Na+ + Cl- what becomes reduced

the Cl to Cl-

Reducing donor

the electron donor

Oxidizing agent

the acceptor

Electron shifts from less electronegative atom to more electronegative which makes the electon

makes the electron lose potential energy

What in the equation becomes oxidized C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

C6H12O6 to 6CO2

What in the equation becomes reduced C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

6O2 to 6H2O

Oxidation of glucose transfers electrons to a

lower energy state which then liberates energy to become available for ATP synthesis

Fuels w/ multiple C-H bonds oxidize into 

C-O bonds

Glucose is broken into key steps, electrons are stripped from the glucose and travel with a hydrogen atom, which is first passed to an electron carrier

electron carrier, the coenzyme NAD+

Oxidized and reduced nicotinamide adenine dinucleotide

Oxidized = NAD+

Reduced = NADH

Removes hydrogen atoms from substrate to oxidize it, delivering the 2 electrons and 1 proton to NAD+ to form NADH

The role of dehydrogenase

What happens to the other proton during the formation of NADH

it is released into the surrounding solution

Electrons _____ potential energy when transferred from _____ to ___

lose, glucose, NAD+

Electron Transport Chain

molecules (mostly proteins) that transport electrons from donors to acceptors via redox reactions

Electrons transfer from _____ to ____ as an exergonic reaction

NADH to oxygen

After transfer NADH to oxygen what happens to the electrons

electrons cascade from one carrier molecule to the next (w/ redox reactions), losing energy ea time until they reach oxygen

ETC Electrons transfer from

glucose to NAD+ to NADH to oxygen

3 (4) Metabolic stages of Cellular Respiration

Glycolysis, Pyruvate oxidation, Krebs, Oxidative phosphorylation

Glycolysis simplified

breakdown of glucose into 2 pyruvate

Citric Acid Cycle simplified

breakdown of glucose to carbon completed. ETC which combines e- at the end to O2 and H+ to make water

Oxidative phosphorylation simplified

energy released fr ETC use to make ATP (fr ADP) these are redox reactions of ETC, adding inorganic phosphate to ADP

Chemiosmosis simplified

oxidative phosphorylation and ETC

Substrate phosphorylation

ATP synthesis occurs when enzyme transfers phosphate group from phosphate to ADP

Total Output of ATP

32

Glycolysis step 1

splitting 6 carbon sugar into two 3 carbon pyruvate via oxidation

Net production of glycolysis

2 ATP, 2 Pyruvate, 2 NADH

Glycolysis can occur even

even without oxygen

If o2 is present in glycoloysis

pyruvate and NADH can be used by other steps of cellular respiration

Where does glycolysis take place

the cytosol

After the pyruvate enters the mitochondria

Co2 is removed and NAD → NADH, formation of acetyl CoA

Basic Kreb Cycle

2 Co2 are oxidized leaving Carbon to combine w/ more carbon at citrate. Cycle is the decomposition of citrate to oxaolacetate

Net product of Krebs Cycle

6 NADH, 2 FADH2, 2 ATP

ETC location

embedded in the inner membrane of the mitochondria

Prosthetic groups

tightly bounded to the protein complexes, nonprotein components that are essential for catalytic functions

Complex I

electrons from glucose by NAD are transferred from NADH to first molecule of ETC in complex I, passes the electron to ubiquinone

Cytochromes

electron carries between ubiquinone and oxygen

Another source for electrons for ETC

FADH2

FADH enters ETC via 

Complex II

Chemiosmosis

The breaking down of free energy into smaller steps

ATP synthase

makes ATP from ADP + inorganic phosphate, uses existing ion gradient to power ATP synthesis

NADH and FADH2 shuttle e- into 4 complexes and 2 electron carrier (ubiquinone and cyt C) they pump protons into intermembrane space

Electron transport chain function

Protons flow down the gradient via ATP synthase and forms ATP

Chemiosmosis function

Proton motive force

force that drives H+ across membrane through H+ channels provided by ATP synthase

Energy flow sequence

glucose → NADH → ETC → proton motive force → ATP

2 mechanisms for ATP generation without oxygen

fermentation and anaerobic respiration

ETC is used in _____ but not blank

Anaerobic respiration and not fermentation

instead of O2 catching electrons in ETC and the by product is H2O

in anaerobic respiration the catcher is So4 and the by product is Hs2

Fermentation

continuous supply of NAD (recycled NADH) in substrate level glycolysis that accepts electrons and turns it into pyruvate

Alcohol fermentation

release of CO2 fr pyruvate → acetadehyde

Acetadehyde is reduced by NADH to ethanol

Lactic acid

pyruvate reduced to NADh to form lactic

White muscle provides fast but

inefficient ATP production

Difference within the three alt pathways of respiration

Fermentation and anaerobic respiration changes final electron acceptor, produces different amounts of ATP

Obligate anaerobes

carry out only fermentation and anaerobic respiration

Facultative anaerobes

make enough ATP to survive using fermentation or respiration

Beta oxidation

breaks down carbons into 2-carbon fragments that enter krebs as CoA