Quiz 04 Questions

Question 1

What aspects of mitosis is NOT universal among all eukaryotic organisms?

Answer 1

Breakdown of nuclear envelope during mitosis

Question 2

ALTERNATIVE QUESTION: What aspects of mitosis IS universal among all eukaryotic organisms?

Answer 2

1. chromatin condensation before mitosis 2. microtubule-based spindle for chromosome segregation 3. spindle with two-fold symmetry for chromosome segragation

Question 3

Describe cell-cell junction that: play a direct role in structural polarization of epithelial cells.

Answer 3

tight junctions

Question 4

Describe cell-cell junction that: usually link a cell contact through integrin bundles

Answer 4

desmosomes (hemi)

Question 5

Describe cell-cell junction that: stabilized by a mechanism comprising of vinculin recruitment

Answer 5

adherens junction

Question 6

Describe cell-cell junction that: create semipermeable paracellular pores

Answer 6

tight junction

Question 7

How do kinsein-5 and kinesin-14 affect the spindle length?

Answer 7

kinesin-5 (+-end directed) lengthens the spindle; whereas kinesin-14 (- end directed) shortens it.

Question 8

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 )?

Answer 8

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

Question 9

Consider two cells attached to each other via adherens junctions. The forces generated by the actin cytoskeleton in one cell …. are?

Answer 9

1. 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

Question 10

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.

Answer 10

Mechanical stresses transmitted from cell-cell by intracellular cytoskeletal filaments anchored to cell-matric and cell-cell adhesion sites

Question 11

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.

Answer 11

Extracellular matrix directly bears the mechanical stresses of tension and compression.

Question 12

tight junctions

Answer 12

1. play a direct role in structural polarization 2. seals gap BETWEEN EPITHELIAL CELLS

Question 13

adherens junction

Answer 13

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

Question 14

desmosome

Answer 14

cell-cell anchoring junction 1. connects intermediate filaments in one cell to those in the next cell (integrin bundles?)

Question 15

hemidesmosome

Answer 15

cell-matrix junctions anchors intermediate filaments in a cell to extracellular matrix

Question 16

During development, how would cells expressing N-cadherin sort themselves out?

Answer 16

Cells expressing N-cadherin will sort out (segregate) from cells expressing E-cadherin

Question 17

During development, how would cells expressing high levels of E-cadherin sort themselves out?

Answer 17

Cells expressing high levels of E-cadherin sort out from cells expressing low levels of E-cadherin.

Question 18

Cells expressing high levels of E-cadherin end up where? Why?

Answer 18

Cells expressing high levels of E-cadherin aggregate in the center (internally) BECAUSE these cells adhere more strongly

Question 19

In vertebrate embryo, changes in cadherin expression are seen when ?

Answer 19

Changes in cadherin expression are seen when the neural tube forms and pinches off from the overlying neural tube

Question 20

In the developing embryo, describe the changes in cadherin expression in corresponding cells

Answer 20

1. Neural tube cells: E-cadherin lost, N-cadherin gained; 2. Ectoderm: continue to express E-cadherin

Question 21

Cadherin 7

Answer 21

1. APPEARS when neural crest cells migrate away from the neural tube 2. holds migrating cells together as loosely associated cell groups

Question 22

What happens when N-cadherin is artificially overexpressed?

Answer 22

cells fail to escape from neural tube

Question 23

What happens to cadherin expression when developing cells aggregate to form a ganglion?

Answer 23

N-cadherin expression turned on

Question 24

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.

Answer 24

C F E D A B

Question 25

Draw a typical mammalian spindle in metaphase comprising, spindle poles, microtubules, and chromosomes. Then label/annotate the three major microtubule classes in the spindle and indicate the position of the plus and minus ends of the microtubule.

Answer 25

Question 26

What phase of cell cycle is the cell in?

Answer 26

G2

Question 27

What phase of mitosis is this cell in?

Answer 27

prophase

Question 28

What phase of mitosis is this cell in?

Answer 28

metaphase

Question 29

What phase of mitosis is this cell in?

Answer 29

anaphase

Question 30

What phase of mitosis is this cell in?

Answer 30

prometaphase