7.1 Flashcards
Define autotrophs
Produced their own organic molecules through photosynthesis
Define heterotrophs
Live on organic compounds produced by other organisms
Explain oxidation reactions
loss of electrons
Explain reduction reactions
gain of electrons
Explain dehydrogenation reactions
lost electrons are accompanied by protons
Define cellular respiration
- Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
- The fuel is oxidized and ultimately the final acceptor is reduced
Explain the role of NAD+ in cellular respiration
- Electrons from organic compounds are usually first transferred to Nicotinamide adenosine dinucleotide (NAD+)
NAD+ accepts 2 electrons and 1 proton to become NADH - NADH passes the electrons to the electron transport chain
- The electron transport chain passes electrons in a series of steps instead of one explosive reaction
- Oxygen pulls electrons down the chain in an energy-yielding tumble
- The energy yielded is used to regenerate ATP
Differentiate fermentation
Absence of oxygen
only uses glycolysis
Final electron acceptor
* Organic molecule
Pyruvate is reduced in order to oxidize NADH back to NAD+
Differentiate aerobic respiration
Presence of oxygen
Final electron acceptor
* Oxygen
Produces significant amount of ATP
Pyruvate is oxidized to acetyl-Co A which enters the citric acid cycle
Differentiate anerobic respiration
Absence of oxygen
Final electron acceptor is an inorganic molecule other than oxygen
Identify the two mechanisms cells use to make ATP
- Substrate-level phosphorylation
- Oxidative phosphorylation
what is substrate-level phosphorylation
Transfer phosphate group directly to ADP
Glycolysis
what is oxidative phosphorylation
ATP synthase uses energy from a proton gradient
Electron transport chain and chemiosmosis
Identify the four stages of cellular respiration
- Glycolysis
Converts glucose to 2 pyruvate molecules - Pyruvate oxidation
Pyruvate is oxidized in the presence of oxygen - Citric acid cycle
oxidize acetyl coA to CO2 - Electron transport chain & chemiosmosis
Identify where in the cell glycolysis occurs
cytoplasm
List the three major phases of glycolysis
- priming reaction
- energy investment - cleavage
- sugar splitting step - oxidation and ATP formation
- energy payoff phase
Describe the process of glycolysis
- “sugar splitting” converts glucose to two molecules of pyruvate
- 10-step biochemical pathway
- Takes place in cytoplasm and has 3 major phases
- Occurs whether or not oxygen is present
- Net production of 2 ATP and 2NADH molecules
Calculate the energy yield from glycolysis
2 ATP
2 NADH
Contrast how NADH is recycled in aerobic respiration
NADH is oxidized by the electron transport chain using oxygen as final electron acceptor
* Electrons are transferred through a series of membrane carriers, ultimately reducing oxygen and forming water
* Occurs in mitochondria
Produces significant amount of ATP
Contrast how NADH is recycled fermentation
Pyruvate is reduced, oxidizing NADH in the absence of oxygen
* Organic molecule is the final electron acceptor
* May be acetaldehyde in ethanolic fermentation (yeast) or when pyruvate itself is directly reduced producing lactate
Explain the fate of pyruvate in aerobic respiration
when oxygen is available
o Starts with oxidation of pyruvate to produce acetyl-CoA which enters the citric acid cycle
Explain the fate of pyruvate in fermentation
when oxygen is unavailable
o Reduces pyruvate to oxidize NADH back to NAD+
Identify where in the cell pyruvate oxidation occurs
mitochondria
Identify where in the cell citric acid cycle occurs
matrix of mitochondria
Identify where in the cell electron transport chain occurs
inner mitochondrial membrane
Describe how pyruvate oxidation links glycolysis with the citric acid cycle
Glycolysis creates pyruvate which creates acetyl-CoA (in the presence of oxygen) which the citric acid cycle can then use in the mitochondria to create energy
Name the complex that catalyzes pyruvate oxidation
pyruvate dehydrogenase
Identify the products of pyruvate oxidation
- 1 CO2
- 1 NADH
- 1 Acetyl-CoA
- multiply by 2 for per glucose molecule
