SI Worksheet #4 (chapter 9)
BY123
Meeting: 6/24/15 @ 1pm in EB 132
1. Fill in the table based on one glucose molecule
Net Production Total ATP
produced/
ATP
invested
Glycolysis
ATP __2___
4/2
NADH __2__
FADH___0____
Pyruvate
__2___
H2o ___2____
Pyruvate
ATP __0___
0/0
Processing
NADH _2___
FADH___0___
CO2 ___2_____
Citric Acid Cycle
aka the Krebs’s
Cycle
ATP __2___
NADH _6___
FADH___2___
CO2 ___4_____
ETC/Chemiosmosis ATP __32___
Utilized
_6___NADH
and _2__FADH
Substrate level
Where does
or oxidative
this occur?
phosphorylation
Aerobic
or
anaerobia
Substrate
Cytosol
anaerobic
Substrate
In eukaryotes aerobic
–
mitochondria
Prokaryotescytosol
Mitochondrial aerobic
matrix
2/0
substrate
32/0
Oxidative
Inner
membrane of
the
mitochondria
aka cristae
aerobic
2. We know now that about 25 ATP actually produced in cellular respiration? Why? Not
completely efficient. Lost as heat
3. Give an example of negative feedback in Cellular respiration? What is the main regulation
mechanism?
a. Increase in pyruvate slows the process down./ ATP content, if it’s high process will
slow
4. Where does each macromolecule (protein, lipid, carb) enter the process of cell respiration?
5. What is fermentation? What is produced? When is this mechanism utilized? Fermentation is
utilized when conditions are anaerobic (No oxygen is available). Fermentation allows
continuous generation of ATP by substrate level phosphorylation by extending glycolysis. It
uses pyruvate as an election acceptor for NADH and pyruvate. 2 net ATP are produced
though glycolysis and fermentation allows the recycling of NADH by shifting the electron to
pyruvate to continue ATP production.
6. What is the difference between aerobic respiration and fermentation? Both generate ATP
without Oxygen. Anaerobic fermentation utilized the ETC with an electronegative molecule
other than oxygen. Fermentation does not.
7. What is Chemiosmosis, how does it relate to the ETC – because of the great buildup of H+
protons outside the complexes and the low concentration of H+ ions inside the complexes
this sets up an electro chemical gradient… The H+ that were sent outside desperately want
to get to an area with a lower H+ concentration. In order to do this they must come back in
through a complex known as the ATP synthase… The movement of H+ through the ATP
synthase results in the creation of ATP. These ATP are made by OXIDATIVE
PHOSPHORYLATION.
8. What is the energy “currency” for the cell? How is this molecule used?
ATP is the energy “currency for the cell. ATP can by hydrolyzed to produce ADP, inorganic
phosphate, and energy. Energy can then be captured from catabolic pathways and used to
reform ATP from ADP and inorganic phosphate.
9. Enzymes act as a biological __catalysts__. What does this mean?
Being a biological catalysts means that an enzyme is a chemical agent that helps to speed up
a reaction without being consumed by the reaction. They speed up the reaction by lowering
the activation energy.
10. What are the ways that the active site of an enzyme lower the activation energy?
The active site of an enzyme lowers the activation energy by orienting the substrate to a
position that will allow it to react easier, by straining bonds which must be broken during
the reaction, by providing a favorable microenvironment, and by forming brief covalent
bonds with the substrate.
11. What is a cofactor? What is a coenzyme?
A cofactor is a non-protein enzyme helper, often inorganic ions. A coenzyme is a cofactor
that is an organic molecule, often a vitamin.
12. Why are catabolic and anabolic pathways often coupled in a cell?
The free energy released from one pathway is used to drive the other pathway.
13. List and describe the three types of major catabolic processes.
The three major catabolic processes are fermentation, anaerobic respiration, and aerobic
respiration. Fermentation is the partial breakdown of sugars or other organic fuel without
the use of O2 or another electronegative molecule. In fermentation, an organic molecule
typically acts as the final electron acceptor. Anaerobic respiration harvests chemical energy
without oxygen. Anaerobic respiration will use another electronegative molecule like SO42or NO3-. Aerobic respiration uses oxygen as the final electron receptor. Both aerobic and
anaerobic respiration are considered cellular respiration.
14. What is being oxidized and reduced in the following equation? What is the oxidizing agent,
and what is the reducing agent?
Mg + 2 Cl → Mg2+ + 2 ClMg is giving electrons to Cl. Therefore, Mg is being oxidized and is the reducing agent. Cl is
accepting electrons from Mg. Therefore, Cl is being reduced and is the oxidizing agent.
a. What is the equation for cellular respiration? What is being oxidized, and what is being
reduced? I have posted a video link that helps to connect the chemistry and biological
perspectives of oxidation and reduction. Worth the watch.
https://www.khanacademy.org/science/biology/cellular-molecular-biology/cellularrespiration/v/oxidation-and-reduction-in-cellular-respiration
15.
16.
17.
18.
C6H12O6 + 6 O2 → 6 H2O + 6 CO2
C6H12O6 is being oxidized and is the reducing agent. O2 is being reduced and is the
oxidizing agent.
Why is cellular respiration a step-wise process instead of occurring all at once?
If the reaction was uncontrolled, then it would be impossible for our cells to capture all of
the energy that is released during the breakdown of organic molecules. By releasing the
energy slowly, cell can use substrate-level phosphorylation and electron acceptors to extract
more of the energy, making the process more efficient.
What are the two main oxidizing agents in cellular respiration? What is the oxidized form
and reduced form of these oxidizing agents?
The two main oxidizing agents used in cellular respiration are NAD+ and FADH. These
molecules function in much of the same way. During the reaction, two protons and two
electrons, so two H atoms, are produced. FADH and NAD+ capture one proton and both
electrons, which are then carried into the electron transport chain to produce ATP. The
oxidized form of these compounds are NAD+ and FADH. This is the form they are in before
they accept electrons. After they accept electrons, they are turned into their reduced forms
which are NADH and FADH2.
What are the two types of fermentation? Explain both.
The two types of fermentation are lactic acid fermentation and alcohol fermentation. In
both reactions, glycolysis proceeds as usual producing pyruvate. In lactic acid fermentation,
pyruvate directly accepts the electrons from NADH and forms lactate. In alcohol
fermentation, CO2 comes out of pyruvate, forming acetaldehyde. Acetaldehyde then
accepts the electrons forming alcohol.
What are the 3 things metabolism does?
a. Growth/reproduction
b. Maintain structures
c. Respond to environment
19. How are cellular respiration and photosynthesis related?
Follow the link for the answer to the question.
https://www.ck12.org/life-science/Connecting-Cellular-Respiration-and-Photosynthesis-inLife-Science/lesson/Connecting-Cellular-Respiration-andPhotosynthesis/?referrer=featured_content
This are just some reference charts that made be useful to you.
SLP
Ox. Phos
Glycolysis
2 ATP Net
2 NADH
1 NADH = 2.5 ATP eq.
1 FADH2 = 1.5 ATP eq.
Ox of Pyruvate
0 ATP
2 NADH
Citric Cycle
2 ATP total
6 NADH & 2 FADH2
4 ATP from SLP
10 NADH x 2.5 ATP eq. = 25 ATP
2 FADH2 x 1.5 ATP eq. = 3 ATP
4 ATP from SLP + 28 ATP from Ox. Phos = 32 ATP