Quiz 04 Questions Flashcards
(30 cards)
What aspects of mitosis is NOT universal among all eukaryotic organisms?
Breakdown of nuclear envelope during mitosis
ALTERNATIVE QUESTION: What aspects of mitosis IS universal among all eukaryotic organisms?
- chromatin condensation before mitosis 2. microtubule-based spindle for chromosome segregation 3. spindle with two-fold symmetry for chromosome segragation
Describe cell-cell junction that: play a direct role in structural polarization of epithelial cells.
tight junctions
Describe cell-cell junction that: usually link a cell contact through integrin bundles
desmosomes (hemi)
Describe cell-cell junction that: stabilized by a mechanism comprising of vinculin recruitment
adherens junction
Describe cell-cell junction that: create semipermeable paracellular pores
tight junction
How do kinsein-5 and kinesin-14 affect the spindle length?
kinesin-5 (+-end directed) lengthens the spindle; whereas kinesin-14 (- end directed) shortens it.
ALTERNATIVE SHORT ANSWER QUESTION: Consider two kinesin motor proteins at the mitotic spindle midzone. What are these motors, how do these motors affect the length of the spindle, which end of microtubule these motors walk toward (specific whether it uses its motor or tail domain )?
Kinesin-5: tetrameric motor directed towards PLUS+ end of both microtubules via its motor domain to lengthen spindle Kinesin-14: walks toward minus end of one microtubule while it is attached to another microtubule via its tail domain to shorten spindle
Consider two cells attached to each other via adherens junctions. The forces generated by the actin cytoskeleton in one cell …. are?
- dependent on myosin activity 2. balanced by similar forces in neighboring cells 3. strengthen the adherens junction by unfolding catenin 4. ****loosen adhesion in response to actin contraction***** **** answer not included in quiz
Mammalian epithelia and connective tissues are regularly subjected to external foces to “try” to pull the cells apart. Describe how epithelia tissue resist these forces in different ways and list the cellular structures that bare the load of these forces.
Mechanical stresses transmitted from cell-cell by intracellular cytoskeletal filaments anchored to cell-matric and cell-cell adhesion sites
Mammalian epithelia and connective tissues are regularly subjected to external foces to “try” to pull the cells apart. Describe how connective tissue resist these forces in different ways and list the cellular structures that bare the load of these forces.
Extracellular matrix directly bears the mechanical stresses of tension and compression.
tight junctions
- play a direct role in structural polarization 2. seals gap BETWEEN EPITHELIAL CELLS
adherens junction
cell-cell anchoring junction 1. connects actin filament bundle in one cell with that in next cell 2. stabilized by a mechanism comprising of vinculin recruitment
desmosome
cell-cell anchoring junction 1. connects intermediate filaments in one cell to those in the next cell (integrin bundles?)
hemidesmosome
cell-matrix junctions anchors intermediate filaments in a cell to extracellular matrix
During development, how would cells expressing N-cadherin sort themselves out?
Cells expressing N-cadherin will sort out (segregate) from cells expressing E-cadherin
During development, how would cells expressing high levels of E-cadherin sort themselves out?
Cells expressing high levels of E-cadherin sort out from cells expressing low levels of E-cadherin.
Cells expressing high levels of E-cadherin end up where? Why?
Cells expressing high levels of E-cadherin aggregate in the center (internally) BECAUSE these cells adhere more strongly
In vertebrate embryo, changes in cadherin expression are seen when ?
Changes in cadherin expression are seen when the neural tube forms and pinches off from the overlying neural tube
In the developing embryo, describe the changes in cadherin expression in corresponding cells
- Neural tube cells: E-cadherin lost, N-cadherin gained; 2. Ectoderm: continue to express E-cadherin
Cadherin 7
- APPEARS when neural crest cells migrate away from the neural tube 2. holds migrating cells together as loosely associated cell groups
What happens when N-cadherin is artificially overexpressed?
cells fail to escape from neural tube
What happens to cadherin expression when developing cells aggregate to form a ganglion?
N-cadherin expression turned on
Sort the following schematic diagrams (A to F) to reflect the order of events in a typical eukaryotic M phase. An interphase cell in G2 is drawn on the left for comparison.
C F E D A B
