Bio 272 Exam 4 Questions and Answers
What is the central goal of the cell cycle? - Correct Answers -to duplicate contents,
divide into 2, and faithfully pass on genetic information to the next generation
What overarching things is the cell cycle essential for? - Correct Answers -reproduction,
growth and development, tissue maintenance (cells need to keep turning over to
maintain homeostasis), tissue repair
What does misregulation of cell division cause? - Correct Answers -birth defects and
miscarriages
What is the hemidesmosome transmembrane adhesion protein? - Correct Answers -
specialized Integrin
What is the hemidesmosome intracellular cytoskeletal attachment? - Correct Answers -
keratin IF
What generates tensile strength in epithelial cells? - Correct Answers -keratin IFs
anchored to desmosomes and hemidesmsomes
function of hemidesmosomes - Correct Answers -anchor keratin IFs to the basal lamina
What binds to the basal lamina on the outside of the cell? - Correct Answers -
specialized integrins
What does misregulation of the cell cycle/cytokinesis cause? - Correct Answers -cancer
What are some examples of non-dividing cells? - Correct Answers -neurons, muscle
cells, other terminally differentiated cells
What are some examples of cells that divide? - Correct Answers -stem cells,
intestinal/skin/other epithelial cells, blood cells
How long is the typical human cell cycle, and how long do cells spend in each phase? -
Correct Answers -24 hours -- 23 hours in interphase, 1 hour in mitosis
purpose of G1 and G2 phases - Correct Answers -allow cells to grow and double the
mass of its proteins and organelles so that they are doubled and ready to divide
,purpose of S phase - Correct Answers -duplication of DNA
purpose of M phase - Correct Answers -- mitosis = nuclear divison
- cytokinesis = cytoplasmic division
G1 phase overview - Correct Answers -cells grow and increase the mass of proteins
and organelles
S phase overview - Correct Answers -DNA replication, centrosome duplication (so that
there can be 2 spindle poles)
G2 phase overview - Correct Answers -DNA exists as chromatids (post duplication),
centrosome separation begins
prophase - Correct Answers -centrosome migration, mitotic spindle begins to form,
chromosomes begin to condense (appear as long threads)
prometaphase - Correct Answers -nuclear envelope breakdown, chromosome
condensation completes, chromosomes attach to spindle microtubules via their
kinetochores
metaphase - Correct Answers -chromosomes align at the equatorial plane of the bipolar
spindle
anaphase - Correct Answers -chromosome separation, kinetochore microtubules
shorten and spindle poles move apart
telophase - Correct Answers -chromosomes decondense, nuclear envelope
reassembles, spindle disassembly begins
cytokinesis - Correct Answers -initiates during anaphase (coordinates with the
chromosomes being pulled apart), cytoplasmic division by the actomyosin contractile
ring, interphase microtubule array re-forms
What is the purpose of flow cytometry? - Correct Answers -- another way to monitor the
cell cycle and allows one-by-one analysis of a large population of cells
- measures the DNA content amount (and thus the stage of the cell cycle)
What is required/what is the process for flow cytometry? - Correct Answers -- requires
separating individual cells from a culture or tissue
- cells in suspension (already separated) are stained with a DNA dye
- increases in intensity based on the amount of DNA its bound to
- individual cells pass through a detector, which detects fluorescence emitted from each
cells
,On a flow cytometry graph, where would you find cells in G1? - Correct Answers --
under the furthest left peak
- less relative DNA per cell (because before S phase)
- also includes any cells that have completed cytokinesis
On a flow cytometry graph, where would you find cells in S? - Correct Answers -in
between peaks
On a flow cytometry graph, where would you find cells in G2 or M? - Correct Answers --
under the furthest right peak
- already duplicated DNA
On a flow cytometry graph where the left peak is taller than the right, how can you tell
what the longest phase of the cell cycle is? - Correct Answers -G1, because the most
cells are captured under that peak
What are the biochemical checkpoints to enter S phase? - Correct Answers -- is the
environment favorable?
- are there sufficient nutrients?
- are there specific signal molecules present telling cells to divide?
What are the biochemical checkpoints to enter M phase? - Correct Answers -- do not
enter mitosis unless DNA is intact
- is all DNA replicated?
- is all DNA damage repaired?
What are the biochemical checkpoints to pull duplicated chromosomes apart? - Correct
Answers -- guards against missegration of chromosomes
- are all chromosomes properly attached to the mitotic spindle?
What does the cell cycle control system depend on? - Correct Answers -cyclin-
dependent kinases (Cdks)
cell machinery - Correct Answers -proteins involved in DNA replication, chromosome
segregation, cytokinesis, etc.
What does the cell cycle control system do to cell machinery? - Correct Answers -turns
cell machinery on and off
How does the cell cycle control system control cell machinery? - Correct Answers -turns
it on and off via phosphorylation and dephosphorylation of the cell cycle machinery
What kind of kinases are Cdks? - Correct Answers -- serine/threonine kinases
- phosphorylate target proteins on serine/threonine residues
What do Cdks form complexes with? - Correct Answers -cyclins
, True or false: cyclins have enzymatic activity on their own - Correct Answers -- false
- they are not kinases
True or false: without cyclins, Cdk is inactive - Correct Answers -true
What happens when Cdk forms a complex with cyclin? (broad overarching result) -
Correct Answers -Cdk is activated to trigger cell cycle events by phosphorylating target
proteins required to initiate these events
True or false: all phases of the cell cycle use the same set of cyclin-Cdk complexes -
Correct Answers -- false
- different phases of the cell cycle use different cyclin-Cdk complexes
- ex. M-Cdk (ex. MPF) is important for regulating M phase; cyclin is Cyclin B and Cdk
partner is Cdk 1
What are the cyclins and Cdks associated with M-Cdk? - Correct Answers -- cyclin -->
cyclin B
- Cdk --> Cdk 1
What kind of subunit are cyclins? - Correct Answers -regulatory subunit
What kind of subunit are Cdks? - Correct Answers -catalytic subunit
How does cyclin concentration change throughout the cell cycle, if at all? - Correct
Answers -cyclins undergo a cycle of synthesis and degradation in each cell cycle
True or false: the protein concentration of cyclins varies cyclically during the cell cycle -
Correct Answers -true
What does the varying of cyclin concentration lead to? - Correct Answers -- drives cyclic
assembly and activation of cyclin-Cdk complexes
- turns on kinase activity of Cdk partners
How does the concentration of Cdk-1 change throughout the cell cycle, if at all? -
Correct Answers -- it does not change
- Cdk-1 concentration remains high and constant throughout the cell cycle
During what phase(s) is the kinase activity of M-Cdk high? - Correct Answers -high only
during mitosis
What does the cycling of the M-cyclin (cyclin B) protein concentration look like? -
Correct Answers -increases gradually throughout interphase and early mitosis, then
drops abruptly during mitosis
What is the central goal of the cell cycle? - Correct Answers -to duplicate contents,
divide into 2, and faithfully pass on genetic information to the next generation
What overarching things is the cell cycle essential for? - Correct Answers -reproduction,
growth and development, tissue maintenance (cells need to keep turning over to
maintain homeostasis), tissue repair
What does misregulation of cell division cause? - Correct Answers -birth defects and
miscarriages
What is the hemidesmosome transmembrane adhesion protein? - Correct Answers -
specialized Integrin
What is the hemidesmosome intracellular cytoskeletal attachment? - Correct Answers -
keratin IF
What generates tensile strength in epithelial cells? - Correct Answers -keratin IFs
anchored to desmosomes and hemidesmsomes
function of hemidesmosomes - Correct Answers -anchor keratin IFs to the basal lamina
What binds to the basal lamina on the outside of the cell? - Correct Answers -
specialized integrins
What does misregulation of the cell cycle/cytokinesis cause? - Correct Answers -cancer
What are some examples of non-dividing cells? - Correct Answers -neurons, muscle
cells, other terminally differentiated cells
What are some examples of cells that divide? - Correct Answers -stem cells,
intestinal/skin/other epithelial cells, blood cells
How long is the typical human cell cycle, and how long do cells spend in each phase? -
Correct Answers -24 hours -- 23 hours in interphase, 1 hour in mitosis
purpose of G1 and G2 phases - Correct Answers -allow cells to grow and double the
mass of its proteins and organelles so that they are doubled and ready to divide
,purpose of S phase - Correct Answers -duplication of DNA
purpose of M phase - Correct Answers -- mitosis = nuclear divison
- cytokinesis = cytoplasmic division
G1 phase overview - Correct Answers -cells grow and increase the mass of proteins
and organelles
S phase overview - Correct Answers -DNA replication, centrosome duplication (so that
there can be 2 spindle poles)
G2 phase overview - Correct Answers -DNA exists as chromatids (post duplication),
centrosome separation begins
prophase - Correct Answers -centrosome migration, mitotic spindle begins to form,
chromosomes begin to condense (appear as long threads)
prometaphase - Correct Answers -nuclear envelope breakdown, chromosome
condensation completes, chromosomes attach to spindle microtubules via their
kinetochores
metaphase - Correct Answers -chromosomes align at the equatorial plane of the bipolar
spindle
anaphase - Correct Answers -chromosome separation, kinetochore microtubules
shorten and spindle poles move apart
telophase - Correct Answers -chromosomes decondense, nuclear envelope
reassembles, spindle disassembly begins
cytokinesis - Correct Answers -initiates during anaphase (coordinates with the
chromosomes being pulled apart), cytoplasmic division by the actomyosin contractile
ring, interphase microtubule array re-forms
What is the purpose of flow cytometry? - Correct Answers -- another way to monitor the
cell cycle and allows one-by-one analysis of a large population of cells
- measures the DNA content amount (and thus the stage of the cell cycle)
What is required/what is the process for flow cytometry? - Correct Answers -- requires
separating individual cells from a culture or tissue
- cells in suspension (already separated) are stained with a DNA dye
- increases in intensity based on the amount of DNA its bound to
- individual cells pass through a detector, which detects fluorescence emitted from each
cells
,On a flow cytometry graph, where would you find cells in G1? - Correct Answers --
under the furthest left peak
- less relative DNA per cell (because before S phase)
- also includes any cells that have completed cytokinesis
On a flow cytometry graph, where would you find cells in S? - Correct Answers -in
between peaks
On a flow cytometry graph, where would you find cells in G2 or M? - Correct Answers --
under the furthest right peak
- already duplicated DNA
On a flow cytometry graph where the left peak is taller than the right, how can you tell
what the longest phase of the cell cycle is? - Correct Answers -G1, because the most
cells are captured under that peak
What are the biochemical checkpoints to enter S phase? - Correct Answers -- is the
environment favorable?
- are there sufficient nutrients?
- are there specific signal molecules present telling cells to divide?
What are the biochemical checkpoints to enter M phase? - Correct Answers -- do not
enter mitosis unless DNA is intact
- is all DNA replicated?
- is all DNA damage repaired?
What are the biochemical checkpoints to pull duplicated chromosomes apart? - Correct
Answers -- guards against missegration of chromosomes
- are all chromosomes properly attached to the mitotic spindle?
What does the cell cycle control system depend on? - Correct Answers -cyclin-
dependent kinases (Cdks)
cell machinery - Correct Answers -proteins involved in DNA replication, chromosome
segregation, cytokinesis, etc.
What does the cell cycle control system do to cell machinery? - Correct Answers -turns
cell machinery on and off
How does the cell cycle control system control cell machinery? - Correct Answers -turns
it on and off via phosphorylation and dephosphorylation of the cell cycle machinery
What kind of kinases are Cdks? - Correct Answers -- serine/threonine kinases
- phosphorylate target proteins on serine/threonine residues
What do Cdks form complexes with? - Correct Answers -cyclins
, True or false: cyclins have enzymatic activity on their own - Correct Answers -- false
- they are not kinases
True or false: without cyclins, Cdk is inactive - Correct Answers -true
What happens when Cdk forms a complex with cyclin? (broad overarching result) -
Correct Answers -Cdk is activated to trigger cell cycle events by phosphorylating target
proteins required to initiate these events
True or false: all phases of the cell cycle use the same set of cyclin-Cdk complexes -
Correct Answers -- false
- different phases of the cell cycle use different cyclin-Cdk complexes
- ex. M-Cdk (ex. MPF) is important for regulating M phase; cyclin is Cyclin B and Cdk
partner is Cdk 1
What are the cyclins and Cdks associated with M-Cdk? - Correct Answers -- cyclin -->
cyclin B
- Cdk --> Cdk 1
What kind of subunit are cyclins? - Correct Answers -regulatory subunit
What kind of subunit are Cdks? - Correct Answers -catalytic subunit
How does cyclin concentration change throughout the cell cycle, if at all? - Correct
Answers -cyclins undergo a cycle of synthesis and degradation in each cell cycle
True or false: the protein concentration of cyclins varies cyclically during the cell cycle -
Correct Answers -true
What does the varying of cyclin concentration lead to? - Correct Answers -- drives cyclic
assembly and activation of cyclin-Cdk complexes
- turns on kinase activity of Cdk partners
How does the concentration of Cdk-1 change throughout the cell cycle, if at all? -
Correct Answers -- it does not change
- Cdk-1 concentration remains high and constant throughout the cell cycle
During what phase(s) is the kinase activity of M-Cdk high? - Correct Answers -high only
during mitosis
What does the cycling of the M-cyclin (cyclin B) protein concentration look like? -
Correct Answers -increases gradually throughout interphase and early mitosis, then
drops abruptly during mitosis
