Chapter 5 Homework Part I.
Starts on page 83
Name: ____________________________________________
1. What type of macromolecule stores the most energy?
lipids
2. How many ATP molecules does it take per second to power an active muscle
cell?
10 million
3. What is the evolutionary reason for the feeling of hunger?
To remind us that it is time for a “fuel stop.” Cellular processes take energy to
function.
4. We can trace the energy stored in all of our food to the sun.
5. Describe what producers and consumers are in terms of energy.
Producers are organisms which convert the energy from the sun (or inorganic
molecules) into usable chemical energy (stored in food molecules).
Consumers obtain food by eating other organisms.
6. What do consumers (including ourselves) obtain from food besides energy?
Important raw materials to build our cells and tissues.
7. What is cellular respiration? What organelle does it take place in (in
eukaryotic cells)?
mitochondria
8. Sketch figure 5.3
See book
9. Briefly describe the following terms:
a. Energy The capacity to perform work
b.
c. Work ---Work moves things in directions in which they would otherwise
not be moved.
d. Kinetic energy –the energy of motion
e. Potential energy-=-energy that an object has because of itrs location or
arrangement.
f. The principle of conservation of energy
It is not possible to create or destroy energy.
g. Heat the random motion of atoms and molecules
h. Entropy a measure of disorder or randomness
i.
Chemical energy Energy stored in the chemical bonds of molecules.
10. What do carbohydrates, fats, and gasoline have in common? They are
especially rich in chemical energy (a special form of potential energy).
11. How do living cells and automobile engines make chemical energy stored in
molecules available for work?
The organic molecules are broken into smaller waste molecules that have
much less chemical energy. In other words, the energy stored in the chemical
bonds is released in chemical reactions in which the molecules are broken
into smaller molecules.
12. What is a calorie? The amount of energy that raises the temperature of 1 gram
of water by 1 degree Celsius.
13. A food Calorie (capital C) is actually a kilocalorie.
14. ATP provides the chemical energy for cellular work.
15. ATP stands for:
Adenosine tri-phosphate
16. Sketch figure 5.7
17. Why is there so much potential energy stored in the outmost bond between
the phosphate groups in the ATP molecule?
Each phosphate group is negatively charged, and the negative charges repel
each other, leading to potential energy.
18. How does ATP cause muscle cells to contract?
ATP transfers phosphate groups to special motor proteins. The proteins
change their shape, causing the muscle cells to contract.
19. Write specific examples of the following types of work conducted by your cells
a. Mechanical work
Movement of cells. Movement of cilia
b. Transport work
The transmission of signals in brain cells
c. Chemical work
The synthesis of large molecules (such as linking amino acids to build
a protein)
20. How is ATP recycled?
A phosphate group is reattached to ADP (adenosine di-phosphate), and
energy is stored in the resulting ATP molecule. This process is mediated by
enzymes.
21. Cellular respiration is aerobic, in other words it requires oxygen.
22. How is breathing related to cellular respiration? (We often use respiration
and breathing synonymously in every day language).
We take in oxygen gas when we breathe, and oxygen gas is a reactant of
aerobic respiration. We release carbon dioxide when we exhale. Carbon
dioxide is a product of cellular respiration.
23. Write the respiration equation here:
C6H12O6 + 6O2  6H2O + 6CO2
24. How many ATP molecules are produced for each glucose molecule consumed
in cellular respiration?
36-38 ATP molecules (Net) for every glucose molecule
25. A. What are Redox reactions? What is redox short for?
Chemical reactions that transfer electrons from one substance to another.
Oxidation-reduction reactions
b. What is oxidation? What is oxidized during respiration?
When a substance loses electrons. Glucose.
c. What is reduction? What is reduced during respiration?
When a substance accepts electrons. Oxygen.
d. Which atom is a stronger “electron grabber” than almost any other type
of atom?
oxygen
26. In the following redox reaction, which compound is oxidized and which is
reduced?
C4H6O5 + NAD+ (oxidized)  C4H4O5 + NADH (reduced) + H+
27. During the fall of an electron heat and light is released.
28. What molecule provides an intermediary step for electrons in the electron
transport chain from glucose to oxygen?
NAD+ (reduced to NADH)
29. What is metabolism?
The general term for all the chemical processes that occur in cells.
30. What is a metabolic pathway?
A series of chemical reactions.
31. A. How many reactions are involved in cellular respiration?
More than a dozen
B. Each of these reactions is catalyzed by a specific enzyme.
32. Summarize each step of cellular respiration (include specifically which
molecules are involved and what happens to them at each step.
A. Glycolysis
Glucose is split into two molecules of a compound called pyruvic acid.
Pyruvic acid donates electrons to NAD+, which is reduced to NADH. This
process takes place in the cytosol.
B. The Krebs Cycle
Pyruvic acid is converted to acetic acid. It enters the Krebs cycle in the
form of acetyl-CoA (acetic acid bonded to a carrier molecule called
coenzyme A). The acetic acid molecule is broken all the way down to
carbon dioxide, which allows the rest of the stored energy in glucose to be
extracted. The products of this step of the reaction are ATP, NADH, and
FADH2. NADH and FADH2 are electron carriers. This process takes place
in the fluid within the mitochondria.
C. Electron Transport
Electrons captured from food by NADH “fall” down electron transport
chains (from electron acceptor molecule to electron acceptor molecule)
to oxygen, the final electron acceptor molecule. This allows the transport
of H+ ions to be pumped across the membrane. When the H+ ions rush
back through ATP synthase complexes ADP is regenerated to ATP. This
process takes place in the proteins embedded in the membrane of the
mitochondria.
33. What is ATP synthase?
Miniature machines constructed from several proteins which make up the
machinery of the electron transport chain.
34. What is the potential energy source that directly drives ATP production by
ATP synthase?
The concentration gradient of the H+ ions being in a higher concentration
outside of the membrane than inside of the membrane.
35. How do carbon monoxide and cyanide poison the body at the molecular level?
Disrupting electron transport in the mitochondria.
36. Name some other types of food molecules which the body can use for food
other than glucose.
Polysaccharides, fats, and proteins.
37. Using figure 5.20, summarize how many ATP molecules are produced in each
step of the cellular respiration reaction, and where in the cell each reaction
occurs.
Glycolysis 2 ATP
Krebs cycle 2 ATP
Electron transport about 34 ATP
38. Based on the cellular location of the steps of the cellular respiration reaction
(#37), which part of the reaction do you expect prokaryotic organisms to be
able to perform?
Glycolysis