BIO 353 LATEST 2026 EXAM QUESTIONS AND ANSWERS
GRADED A+
✔✔Compare your responses to the correct responses below. Consider the phases of
the cell cycle listed below. Can a cancerous cell go through the cell cycle in these
different phases of the cell cycle? - ✔✔Interphase Spherical: Yes Interphase Pancake-
Shaped: Yes
G1 Phase Spherical: Yes
G1 Phase Pancake-Shaped: Yes
G2 Phase Spherical: Yes
G2 Phase Pancake-Shaped: Yes
S Phase Spherical: Yes
S Phase Pancake-Shaped: Yes
✔✔Why would a pharmaceutical company want to use a cell line rather than a primary
culture or a secondary culture? - ✔✔If a researcher or pharmaceutical company were
studying the effects of a drug that would lower cholesterol production in the liver (i.e.,
LDL, often referred to as bad cholesterol), then ideally the researcher/pharmaceutical
company would want to be studying liver cells (cell type name, hepatocytes). When a
cell line is made from a single hepatocyte cell (with conditioned medium), then for a
period of time the phenotype (based on differential gene expression) will be that of
hepatocytes. A primary or secondary culture would have a mixed population of cells that
could include skeletal muscle cells, fibroblasts, macrophages and other white blood
cells. Results from studies of drugs on this mixed population of cells types would not
produce meaningful results.
✔✔Human cells are kept at 37°C. Do you think a change to the temperature by 3°C
would be more hazardous to the cell line if it were added, or subtracted? In other words,
is a temperature of 40°C or 34°C more likely to result in detrimental effects? - ✔✔40°C
is a more dangerous temperature for cells. Cells can be cooled without suffering
appreciable damage - in fact, cells are often frozen for long-term storage and re-
animated when needed. Enough thermal energy, however, will permanently denature
the enzymes and other cellular proteins resulting in cell death.
✔✔Why would the evolutionary timeline of the eukaryotic cell require a loss of the cell
wall before the process of endosymbiosis? - ✔✔Engulfing another organism by
phagocytosis is not possible with a cell wall.
✔✔Describe how cholesterol protects the lipid bilayer from freezing. - ✔✔Cholesterol
depresses the freezing point of the lipids by keeping the fatty acid tails shifting around
the cholesterol as they try to shift from the liquid crystal to gel state when the external
temperature is lowered.
✔✔Phospholipids are amphipathic. What does this mean? - ✔✔Amphipathic molecules
have hydrophobic and hydrophilic regions within the same molecule.
, ✔✔There is a long chain of amino acids with long sections that are mostly polar,
alternating with long sections that are nonpolar. How would this chain be organized if it
were destined to become a transmembrane protein? A cytoplasmic protein? - ✔✔In a
transmembrane protein, the hydrophobic portions would be localized to interact with the
hydrophobic portion of the membrane (i.e. the hydrophobic tails of the lipids) in the
exterior of the protein, while the hydrophilic portions would interact with the portions of
the membrane exposed to the aqueous environment and the head groups of the lipid. In
cytoplasmic proteins (i.e. proteins exposed to the aqueous environment of the cell), the
polar amino acids would be on the exterior of the protein. Here, the hydrogen bonding
and charge interactions are taking place with the aqueous cytoplasm, and the nonpolar
portions are sequestered to the center of the protein.
✔✔Explain gated transport for a transmembrane protein. - ✔✔Gated transport involves
protein channels that selectively open when stimulated by a ligand in the case of ligand-
gated channels, or a voltage threshold in the case of voltage-gated channels.
✔✔Describe the size and shape of an actin filament. - ✔✔Actin filaments have diameter
of 7 nm and can be various lengths in the cell, depending on the number of monomers
present in the linear array of actin filaments. The monomers are proteins that have a
globular/dumbbell shape. The monomer has a molecular weight of 42 kD and is
composed of 375 amino acids.
✔✔Describe how the presence of ATP contributes to actin filament assembly and
polarity. - ✔✔When ATP is present in the monomer, the monomer has a conformation
that promotes its self-assembly into an actin filament, assuming the monomer
concentration is high enough.
✔✔The primitive protoprokaryote likely acquired motility before it lost the cell wall. -
✔✔False
✔✔The medium in the primary explant contains PBS made 0.5 % with trypsin and 3mM
with MgCl2. - ✔✔True
✔✔In primary culture all cells survive. - ✔✔False
✔✔Peroxisomes likely originated from the endomembrane system. - ✔✔True
✔✔Of the following select the 3 most crucial ions required for maintaining proper
osmolarity and membrane potential. - ✔✔Chloride ions
Sodium ions
Potassium ions
✔✔Contact inhibition is a subset of - ✔✔anchorage dependence for growth
GRADED A+
✔✔Compare your responses to the correct responses below. Consider the phases of
the cell cycle listed below. Can a cancerous cell go through the cell cycle in these
different phases of the cell cycle? - ✔✔Interphase Spherical: Yes Interphase Pancake-
Shaped: Yes
G1 Phase Spherical: Yes
G1 Phase Pancake-Shaped: Yes
G2 Phase Spherical: Yes
G2 Phase Pancake-Shaped: Yes
S Phase Spherical: Yes
S Phase Pancake-Shaped: Yes
✔✔Why would a pharmaceutical company want to use a cell line rather than a primary
culture or a secondary culture? - ✔✔If a researcher or pharmaceutical company were
studying the effects of a drug that would lower cholesterol production in the liver (i.e.,
LDL, often referred to as bad cholesterol), then ideally the researcher/pharmaceutical
company would want to be studying liver cells (cell type name, hepatocytes). When a
cell line is made from a single hepatocyte cell (with conditioned medium), then for a
period of time the phenotype (based on differential gene expression) will be that of
hepatocytes. A primary or secondary culture would have a mixed population of cells that
could include skeletal muscle cells, fibroblasts, macrophages and other white blood
cells. Results from studies of drugs on this mixed population of cells types would not
produce meaningful results.
✔✔Human cells are kept at 37°C. Do you think a change to the temperature by 3°C
would be more hazardous to the cell line if it were added, or subtracted? In other words,
is a temperature of 40°C or 34°C more likely to result in detrimental effects? - ✔✔40°C
is a more dangerous temperature for cells. Cells can be cooled without suffering
appreciable damage - in fact, cells are often frozen for long-term storage and re-
animated when needed. Enough thermal energy, however, will permanently denature
the enzymes and other cellular proteins resulting in cell death.
✔✔Why would the evolutionary timeline of the eukaryotic cell require a loss of the cell
wall before the process of endosymbiosis? - ✔✔Engulfing another organism by
phagocytosis is not possible with a cell wall.
✔✔Describe how cholesterol protects the lipid bilayer from freezing. - ✔✔Cholesterol
depresses the freezing point of the lipids by keeping the fatty acid tails shifting around
the cholesterol as they try to shift from the liquid crystal to gel state when the external
temperature is lowered.
✔✔Phospholipids are amphipathic. What does this mean? - ✔✔Amphipathic molecules
have hydrophobic and hydrophilic regions within the same molecule.
, ✔✔There is a long chain of amino acids with long sections that are mostly polar,
alternating with long sections that are nonpolar. How would this chain be organized if it
were destined to become a transmembrane protein? A cytoplasmic protein? - ✔✔In a
transmembrane protein, the hydrophobic portions would be localized to interact with the
hydrophobic portion of the membrane (i.e. the hydrophobic tails of the lipids) in the
exterior of the protein, while the hydrophilic portions would interact with the portions of
the membrane exposed to the aqueous environment and the head groups of the lipid. In
cytoplasmic proteins (i.e. proteins exposed to the aqueous environment of the cell), the
polar amino acids would be on the exterior of the protein. Here, the hydrogen bonding
and charge interactions are taking place with the aqueous cytoplasm, and the nonpolar
portions are sequestered to the center of the protein.
✔✔Explain gated transport for a transmembrane protein. - ✔✔Gated transport involves
protein channels that selectively open when stimulated by a ligand in the case of ligand-
gated channels, or a voltage threshold in the case of voltage-gated channels.
✔✔Describe the size and shape of an actin filament. - ✔✔Actin filaments have diameter
of 7 nm and can be various lengths in the cell, depending on the number of monomers
present in the linear array of actin filaments. The monomers are proteins that have a
globular/dumbbell shape. The monomer has a molecular weight of 42 kD and is
composed of 375 amino acids.
✔✔Describe how the presence of ATP contributes to actin filament assembly and
polarity. - ✔✔When ATP is present in the monomer, the monomer has a conformation
that promotes its self-assembly into an actin filament, assuming the monomer
concentration is high enough.
✔✔The primitive protoprokaryote likely acquired motility before it lost the cell wall. -
✔✔False
✔✔The medium in the primary explant contains PBS made 0.5 % with trypsin and 3mM
with MgCl2. - ✔✔True
✔✔In primary culture all cells survive. - ✔✔False
✔✔Peroxisomes likely originated from the endomembrane system. - ✔✔True
✔✔Of the following select the 3 most crucial ions required for maintaining proper
osmolarity and membrane potential. - ✔✔Chloride ions
Sodium ions
Potassium ions
✔✔Contact inhibition is a subset of - ✔✔anchorage dependence for growth
