Download Name Cellular Respiration Use Chapter 7 of your book to complete

Name ____________________________________
Cellular Respiration
Use Chapter 7 of your book to complete this packet.
Harvesting Chemical Energy
1. The energy stored in organic compounds such as glucose must be released by cellular
respiration so that the energy can be used by cells to do work. In what form is the energy
made available to cells?
2. Write the equation for cellular respiration.
3. Cellular respiration can be divided into two stages. Briefly summarize what each stage
accomplishes:
a. Glycolysis
b. Aerobic respiration
4. What does aerobic mean?
5. In which stage of cellular respiration is most of the ATP created?
6. What role does NADH play is cellular respiration?
Glycolysis
7. List the three things that are produced by glycolysis of one molecule of glucose:
8. Why is it necessary to talk about a “net yield” of ATP from glycolysis?
Fermentation
9. Under what conditions does fermentation occur? Will it ever happen in animal cells?
10. What is the point of fermentation?
11. How many molecules of ATP does fermentation produce from the pyruvic acid produced
from one molecule of glucose?
12. What are the two forms of fermentation? What kinds of organisms do which form?
13. What products have humans learned to create from each type of fermentation?
Efficiency of Glycolysis
14. What unit is used to describe the energy available in a molecule?
15. How much energy is available in a molecule of glucose?
16. How good is glycolysis in terms of releasing the available energy?
17. After glycolysis, where is most of the remaining energy that was originally present in the
starting molecule of glucose?
Aerobic Respiration
18. When pyruvic acid enters the mitochondrion, it reacts with coenzyme A to form acetyl CoA
which can then enter the Krebs cycle. What else is produced by this reaction? What
becomes of each of these other products?
19. The set of chemical reactions known as the Krebs cycle takes place in the mitochondrial
matrix. Why do we call these reactions a cycle?
20. Acetyl CoA (with 2 Carbons) reacts with oxaloacetic acid (4 Carbons) to form citric acid
(with 6 carbons). What do the remaining reactions do with the carbons from acetyl CoA?
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21. What else is produced by the Krebs cycle (three different molecules)?
22. How many “turns” of the Krebs cycle are required to deal with the products of one starting
molecule of glucose?
23. By the end of the Krebs cycle, how many molecules of ATP (net gain) have been produced?
NADH?
FADH2?
Electron Transport Chain and Chemiosmosis
24. The electron transport chain (ETC) takes place in the mitochondrial inner membrane, the
folds of which are called cristae. The membrane contains many special proteins that can
accept electrons from NADH and FADH2 in the matrix, and can pass these electrons along
(transport them!) to other molecules in the membrane. What else is lost from NADH and
FADH2?
What low energy molecules are produced?
25. As the electrons are passed along the ETC, they gradually lose energy. Some of this energy
is used to actively transport what?
What is accomplished by this pumping?
26. Hydrogen ions (protons) are allowed to flow back to the matrix across the membrane through
a special protein channel. What is this channel and what is made as the electrons flow
through it?
27. What molecule finally accepts the electrons once their energy has been depleted?
H+ ions are also accepted and a stable, low energy molecule is produced. What is this
molecule?
28. As a result of gradually releasing the electrons and pumping protons (ETC and
chemiosmosis), how many molecules of ATP may possibly be created?
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29. Count ‘em up! How molecules of ATP in total may be produced from the complete
processing of one molecule of glucose? Why is the actual total typically lower?
Efficiency of cellular respiration
30. Compare the efficiency of aerobic respiration with that of glycolysis.
A Summary of Cellular Respiration
31. Draw a sketch of a mitochondrion and label the cristae (inner mitochondrial membrane) and
the matrix. Show 1) where glycolysis happens, and what products result, 2) draw arrows to
show where the products of glycolysis are used, 3) how many ATP can be produced in each
respiratory process, 4) where CO2 is produced, 5) where oxygen is produced and 6) where
H2O is produced. Also show where the electron carriers NADH and FADH2 are produced in
the mitochondrion and where they are used. Show what happens to the oxidized (low energy
forms) of these molecules.
Time to think!
32. If O2 were not available, the ETC would stop. Why?
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33. Why would the absence of O2 ultimately result in a halt of glycolysis, an anaerobic process?
(Hint: you have created a reduced electron carrier but you can’t oxidize it.)
34. Without O2, pyruvic acid does not enter the mitochondrion, but stays in the cytoplasm. What
happens to it to ensure that at least glycolysis can continue to produce some ATP from
available glucose?
35. A terrarium is a totally enclosed container, usually of glass, that contains soil and living
plants. Once the plants are set in the soil, they are watered and the cover is set in place. The
terrarium just needs light and the plants will grow for many months without access to
additional air or water. Explain.
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