Chapter 9 - cellular Respiration Flashcards
what is fermentation?
partial degradation of sugars or other organic fuel that occurs without the use of oxygen
glycolysis
initial/partial breakdown of glucose (regardless of O2)
what is aerobic respiration?
consumes organic molecules and O2 (final electron acceptor) to yield ATP via the electron transport chain (very efficient!)
Glucose →(glycolysis) → pyruvate → acetyl CoA
what is anaerobic respiration?
similar to aerobic respiration but instead of O2, another inorganic molecules (such as NO3, SO3, or CO2) is used as the final electron acceptor (less efficient than O2 but better than fermentation)
produces a limited amount of ATP (no ETC)
how is NADH formed?
2 hydrogen atoms and 2 e- are taken from glucose/food
1 hydrogen atom, 2 e- are bonded to NAD+
how is NADH formed in cellular respiration?
1) hydrogen that reacts with oxygen is derived from an organic molecule, not H2
2) electron transport chain is used to break the fall of the electrons to oxygen into several steps
what is the electron transport chain?
it consists of a number of molecules mostly proteins, built into the inner membrane of the mitochondria of eukaryotic cells
electrons removed from glucose are shuttled by NAHD to the higher energy end of the ETC and at the lower energy end O2 captures these electrons along with H+, forming water
exergonic rxn
what is the path of an electron during cellular respiration?
glucose –> NADH –> ETC –> oxygen
what are the stages of cellular respiration?
1) glycolysis
2) pyruvate oxidation/citric acid cycle
3) oxidative phosphorylation
where does glycolysis occur?
cytosol
breaks down glucose into two molecules of pyruvate
pyruvate then enters the mitochondrion and is oxidized to a acetyl CoA
acetyl CoA enters citric acid cycle where the breakdown of glucose to CO2 is competed
(in prokaryotic cells this happens in the cytosol too)
what is oxidative phosphorylation?
th energy released at each step of the chain in the formation of NADH and then the ETC and formation of water is stored in a form the mitochondria can use to make ATP from ADP - this mode of ATP synthesis is called oxidative phosphorylation because it is powered by the red reaction of the electron transport chain
what is substrate level phosphorylation?
when ATP is directly formed in a few reactions of glycolysiss and the citric acid cycle when an enzyme transfers a phosphate group from a substrate to ADP
substrate = m-c generated as intermediate during catabolism of glucose
glycolysis
- can occur with or without oxygen!
- no CO2 released, # of carbon is conserved!
- substrate-level phosphorylation
- energy investment phase (-2ATP) and energy payoff phase (+4ATP, +4NADH)
- net: 2 ATP, 2 NADH/glucose
glucose –> 2pyruvate + 2H2O
if O2 is present, pyruvate oxidation, citric acid cycle, and oxidative phosphorylation can happen`
what is pyruvate oxidation?
1) pyruvate enters mitochondria via active transport on carrier protein
2) carboxyl group of pyruvate turns into CO2
3) NAD+ –> NADH
4) Acetyl CoA (goes into Krebb’s)
exergonic reactiion
occurs in mitochondria
what is the citric acid cycle?
net/glucose: 6NADH, 2FADH2, 2ATP, 4CO2 released
occurs in the presence of O2 happens in mitochondrial matrix All carbons from glucose are lost as CO2 acetyl CoA enters Krebb's cycle ATP made through substrate-level phosphorylation