Chapter 9 Flashcards
Energy enters an ecosystem as ____ and exits as ______
sunlight; heat
What releases the energy stored in glucose during cellular respiration? What is this released energy used for?
- The transfer of electrons
- Used to synthesize ATP
Cellular respiration is a ______ reaction
exergonic
Redox reaction
Reaction with transfer of electrons between reactants
Oxidation
A substances loses electrons and is oxidized
Reduction
A substance gains electrons and is reduced.
In this equation: Na + Cl = Na+ + Cl- Which is oxidized and which is reduced?
-Na is oxidized, Cl is reduced
Remember that Na loses electrons, and therefore has more protons. It has a positive charge. Cl gains electrons and has less protons that electrons. Its charge is reduced to negative.
Reducing agent
Electron donor; this would be the substance that is oxidized
Oxidizing agent
Electron receptor; this would be the substance that is reduced
Some redox reactions do not transfer electrons but change _______
electron sharing in covalent bonds
In cellular respiration, which is oxidized and which is reduced?
- Glucose is oxidized
- Oxygen is reduced
In a molecule of H2O, which atom is reduced?
Oxygen is reduced as electrons of covalent bonds tend to gravitate towards it more
Oxidation of glucose transfers electrons to a ____ free energy level
Lower; they lose potential energy along the way
What is NAD+
An electron carrier coenzyme
NAD+ functions as a _____ agent during cellular respiration
Oxidizing
-Remember that NAD+ receives electrons, therefore it is reduced. So, it is an oxidizing agent.
What does NADH represent?
Stored energy that is tapped to synthesize ATP
What electron transfer is coupled with the reduction of NAD+?
The oxidation of glucose
(Dehydrogenase enzymes remove 2 hydrogen atoms from glucose, thus oxidizing it, and then delivers 2 electrons and 1 proton to NAD+)
What do dehydrogenase enzymes do?
Oxidize glucose by removing 2 hydrogen atoms and delivers it to NAD+
The Electron Transport Chain passes electrons down the chain until it meets _____, which is the stable and electron acceptor
O2
The energy yielded from which process is used to generate ATP?
Electron Transport Chain
Which process generates the most ATP and why?
Oxidative phosphorylation and because it is powered by redox reactions
Which 2 processes generate the least ATP and why?
Glycolysis and Citric Acid Cycle because it is fueled by substrate-level phosphorylation
What is substrate-level phosphorylation?
Transfer of phosphate group from organic substrate to ADP
Glycolysis breaks glucose into __(number)__ molecules of _____
2 molecules of pyruvate
Where does glycolysis occur and what are its phases?
In cytoplasm, energy investment phase and energy payoff phase
What are the products of glycolysis?
-2 pyruvate and 2 H2O, 2 ATP, 2 NADH and 2 H+
The 2 ATP is produced by substrate-level phosphorylation and the NAD+ is reduced to NADH
What does the Citric Acid Cycle ultimately do?
Completely oxidizes glucose in the presence of oxygen
What happens before Krebs cycle begins and after glycolysis?
Carbon is lost as carbon dioxide, 2-carbon molecule combines with CoA to form acetyl CoA
What is the final electron acceptor in oxidative phosphorylation?
Oxygen
More H+ ions = _____ pH
Lower
The electron transport chain sends H+ from where to where?
Matrix to intermembrane space
How does the exergonic flow of H+ ions create ATP?
Catabolic pathway of H+ across membrane through ATP synthase conforms ADP and phosphate group
What is chemiosmosis?
Use of energy in an H+ gradient to drive work
What are the types of fermentation? What happens in these?
- Alcohol: CO2 released from pyruvate, then that is oxidized. Ethanol is final.
- Lactic: Pyruvate oxidized right away, creating lactate
Obligate anaerobe
Carry out fermentation and cannot survive in O2
What three organic molecules are often utilized to make ATP by cellular respiration?
Proteins, fats, carbohydrates
Why don’t cells catabolize carbon dioxide?
CO2 is already completely oxidized
