Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
1. Consider some questions about cell structure or function that you
would be interested in answering. Would the data required to answer
the question be easier to collect by working on an entire plant or
animal or on a population of cultured cells? What might be the
advantages and disadvantages of working on a whole organism
versus a cell culture?
Ans: The specific answer would depend on the question asked.
Advantages of working with a cell culture include the ability to study
a single cell type, ease of obtaining large numbers of cells, ability to
minimize number of unknown variables by using carefully controlled
in vitro conditions. The advantage of using a whole organism is that
information obtained is more meaningful in understanding the role
of the process in the overall activity of the organism. For example,
one might want to study glucose transport across the plasma
membrane of cultured liver cells in response to insulin, but the
results would not tell you much about the role of this process in
maintaining proper blood glucose levels.
Difficulty: Difficult
Section Reference:
1.2
2. Figure 1.3 shows an intestinal epithelial cell with large numbers of
microvilli. What is the advantage to the organism of having these
microvilli? What do you expect would happen to an individual that
lacked such microvilli as the result of an inherited mutation?
Ans: They greatly increase the surface area/volume ratio of the cell,
allowing much greater exchange between the cell and the lumen of
the intestine. Would be unable to absorb sufficient nutrients from
the lumen to survive.
Difficulty: Medium
Section Reference:
1.2
Page 1
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
3. The first human cells to be successfully cultured were derived from a
malignant tumor. Do you think this simply reflects the availability of
cancer cells, or might such cells be better subjects for cell culture?
Why?
Ans: Cancer cells grow in a much less controlled manner than normal
cells, which is why they continue to proliferate in the body. Cancer
cells tend to have fewer requirements for growth and are therefore
more readily cultured in diverse media than normal cells. Culturing
such cells was a logical first step in the development of culture
conditions.
Difficulty: Difficult
Section Reference:
1.2
4. The drawings of plant and animal cells in Figure 1.8b,c include certain
structures that are present in plant cells but absent in animal cells.
How do you think each of these structures affects the life of the
plant?
Ans: A major difference between plant and animal cells is the presence of
chloroplasts and their associated light harvesting molecules which
allow plants to convert light energy to ATP. Plant cells also typically
have large vacuoles that consist of fused membrane bound
organelles. In plants, vacuoles are often filled with water and help
maintain hydrostatic pressure or turgor.
Difficulty: Difficult
Section Reference:
1.3
Page 2
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
5. It was noted that cells possess receptors on their surface that allow
them to respond to specific stimuli. Many cells in the human body
possess receptors that allow them to bind specific hormones that
circulate in the blood. Why do you think these hormone receptors are
important? What would be the effect on the physiological activities of
the body if cells lacked these receptors, or if all cells had the same
receptors?
Ans: These receptors mark specific cells as targets for particular
hormones. Without such receptors, cells would not be able to bind a
specific hormone and thus would not be able to respond to it. If all
cells had the same receptors, hormones would not be able to
selectively activate specific target cells. All cells would become
potential targets.
Difficulty: Easy
Section Reference:
1.2
6. If you were to argue that viruses are living organisms, what features
of viral structure and function might you use in your argument?
Ans: That viruses contain genetic material; that they are capable of
producing more of themselves, albeit only inside a host cell; that
they contain complex biological macromolecules; that they evolve.
These are all important criteria of living organisms.
Difficulty: Difficult
Section Reference:
1.8
7. If we presume that activities within cells do occur in a manner
analogous to that shown in the Rube Goldberg cartoon of Figure 1.7,
how would this differ from a human activity, such as building a car on
an assembly line or shooting a free throw in a basketball game?
Ans: Activities in cells are not directed by agents with a conscious,
purposeful goal. Activities that occur in a cell must be directed and
regulated by mechanisms operating within the system.
Difficulty: Difficult
Section Reference:
1.2
Page 3
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
8. Unlike bacterial cells, the nucleus of a eukaryotic cell is bounded by a
double-layered membrane studded by complex pores. How do you
think this might affect traffic between the DNA and cytoplasm of a
eukaryotic cell compared to that of a prokaryotic cell?
Ans: The nuclear envelope that separates the nucleus and cytoplasm in a
eukaryotic cell provides the basis for regulating the movement of
substances between the two compartments. The DNA of a bacterial
cell is presumably much more accessible to cytoplasmic substances
than that of a eukaryotic cell.
Difficulty: Easy
Section Reference:
1.3
9. Examine the photograph of the ciliated protist in Figure 1.16 and
consider some of the activities in which this cell engages that a
muscle or nerve cell in your body does not.
Ans: Such as, the capture and uptake of other organisms, the sensing of
conditions in the external environment and making the appropriate
responses, the ability for locomotion. Most activities of this cell are
shared by a muscle or nerve cell.
Difficulty: Difficult
Section Reference:
1.5
10. Which type of cell would you expect to achieve the largest volume: a
highly flattened cell or a spherical cell? Why?
Ans: A highly flattened cell because it will have a much greater surface
area/volume ratio.
Difficulty: Medium
Section Reference:
1.3
Page 4
1. Consider some questions about cell structure or function that you
would be interested in answering. Would the data required to answer
the question be easier to collect by working on an entire plant or
animal or on a population of cultured cells? What might be the
advantages and disadvantages of working on a whole organism
versus a cell culture?
Ans: The specific answer would depend on the question asked.
Advantages of working with a cell culture include the ability to study
a single cell type, ease of obtaining large numbers of cells, ability to
minimize number of unknown variables by using carefully controlled
in vitro conditions. The advantage of using a whole organism is that
information obtained is more meaningful in understanding the role
of the process in the overall activity of the organism. For example,
one might want to study glucose transport across the plasma
membrane of cultured liver cells in response to insulin, but the
results would not tell you much about the role of this process in
maintaining proper blood glucose levels.
Difficulty: Difficult
Section Reference:
1.2
2. Figure 1.3 shows an intestinal epithelial cell with large numbers of
microvilli. What is the advantage to the organism of having these
microvilli? What do you expect would happen to an individual that
lacked such microvilli as the result of an inherited mutation?
Ans: They greatly increase the surface area/volume ratio of the cell,
allowing much greater exchange between the cell and the lumen of
the intestine. Would be unable to absorb sufficient nutrients from
the lumen to survive.
Difficulty: Medium
Section Reference:
1.2
Page 1
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
3. The first human cells to be successfully cultured were derived from a
malignant tumor. Do you think this simply reflects the availability of
cancer cells, or might such cells be better subjects for cell culture?
Why?
Ans: Cancer cells grow in a much less controlled manner than normal
cells, which is why they continue to proliferate in the body. Cancer
cells tend to have fewer requirements for growth and are therefore
more readily cultured in diverse media than normal cells. Culturing
such cells was a logical first step in the development of culture
conditions.
Difficulty: Difficult
Section Reference:
1.2
4. The drawings of plant and animal cells in Figure 1.8b,c include certain
structures that are present in plant cells but absent in animal cells.
How do you think each of these structures affects the life of the
plant?
Ans: A major difference between plant and animal cells is the presence of
chloroplasts and their associated light harvesting molecules which
allow plants to convert light energy to ATP. Plant cells also typically
have large vacuoles that consist of fused membrane bound
organelles. In plants, vacuoles are often filled with water and help
maintain hydrostatic pressure or turgor.
Difficulty: Difficult
Section Reference:
1.3
Page 2
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
5. It was noted that cells possess receptors on their surface that allow
them to respond to specific stimuli. Many cells in the human body
possess receptors that allow them to bind specific hormones that
circulate in the blood. Why do you think these hormone receptors are
important? What would be the effect on the physiological activities of
the body if cells lacked these receptors, or if all cells had the same
receptors?
Ans: These receptors mark specific cells as targets for particular
hormones. Without such receptors, cells would not be able to bind a
specific hormone and thus would not be able to respond to it. If all
cells had the same receptors, hormones would not be able to
selectively activate specific target cells. All cells would become
potential targets.
Difficulty: Easy
Section Reference:
1.2
6. If you were to argue that viruses are living organisms, what features
of viral structure and function might you use in your argument?
Ans: That viruses contain genetic material; that they are capable of
producing more of themselves, albeit only inside a host cell; that
they contain complex biological macromolecules; that they evolve.
These are all important criteria of living organisms.
Difficulty: Difficult
Section Reference:
1.8
7. If we presume that activities within cells do occur in a manner
analogous to that shown in the Rube Goldberg cartoon of Figure 1.7,
how would this differ from a human activity, such as building a car on
an assembly line or shooting a free throw in a basketball game?
Ans: Activities in cells are not directed by agents with a conscious,
purposeful goal. Activities that occur in a cell must be directed and
regulated by mechanisms operating within the system.
Difficulty: Difficult
Section Reference:
1.2
Page 3
, Chapter 01: Analytic Questions, Introduction to the Study of Cell and Molecular Biology
8. Unlike bacterial cells, the nucleus of a eukaryotic cell is bounded by a
double-layered membrane studded by complex pores. How do you
think this might affect traffic between the DNA and cytoplasm of a
eukaryotic cell compared to that of a prokaryotic cell?
Ans: The nuclear envelope that separates the nucleus and cytoplasm in a
eukaryotic cell provides the basis for regulating the movement of
substances between the two compartments. The DNA of a bacterial
cell is presumably much more accessible to cytoplasmic substances
than that of a eukaryotic cell.
Difficulty: Easy
Section Reference:
1.3
9. Examine the photograph of the ciliated protist in Figure 1.16 and
consider some of the activities in which this cell engages that a
muscle or nerve cell in your body does not.
Ans: Such as, the capture and uptake of other organisms, the sensing of
conditions in the external environment and making the appropriate
responses, the ability for locomotion. Most activities of this cell are
shared by a muscle or nerve cell.
Difficulty: Difficult
Section Reference:
1.5
10. Which type of cell would you expect to achieve the largest volume: a
highly flattened cell or a spherical cell? Why?
Ans: A highly flattened cell because it will have a much greater surface
area/volume ratio.
Difficulty: Medium
Section Reference:
1.3
Page 4
