Cell 7

Question 1

Where is nuclear lamina located?

Answer 1

just deep to the inner nuclear membrane

Question 2

What makes up the nuclear lamina?

Answer 2

3 different types of intermediate filaments referred to as lamins

Question 3

What’s the function of lamins?

Answer 3

they are involved with disassembly and re-assembly of nuclear envelope during mitosis

Question 4

What causes Progeria?

Answer 4

defect in nuclear lamins

Question 5

What is the role of lamins in prophase of mitosis?

Answer 5

disassembly of nuclear enevelope, mediated by phosphorylation of the lamins making up the nuclear lamina

Question 6

What is the role of lamins in telophase of mitosis?

Answer 6

reassembly of nuclear envelope, dephosphorylation of lamins

Question 7

What is heterochromatin?

Answer 7

tightly coiled chromatin

Question 8

What is euchromatin?

Answer 8

loosely coiled chromatin

Question 9

Which will stain more densely, heterochromatin or euchromatin?

Answer 9

heterochromatin will stain more densely in a basic dye

Question 10

What is the distinctive feature in a stain for papillary thyroid cancer?

Answer 10

Orphan Annie eye nuclei “clear eye”

Question 11

What is nucleostemin?

Answer 11

p53 binding protein found in undifferentiated cells.

Question 12

As cells become more differentiated, what happens to the level of nucleostemin?

Answer 12

decreases thus p53 is active and functional, and can control the cell cycle

Question 13

The presence of nucleostemin in cancer cells is indicative of what?

Answer 13

unchecked proliferation due to the inactivation of p53

Question 14

What is in pars fibrosa within the nucleolus?

Answer 14

heavy ribosomal RNA, proteins coming in from the cytoplasm also go here

Question 15

What is in pars granulosa within the nucleolus?

Answer 15

maturation of ribosomal subunits and appear more granulated

Question 16

What are the phases of interphase?

Answer 16

G1, S, G2

Question 17

What occurs in G1?

Answer 17

restriction checkpoint before proceeding to S phase, most variable stage in terms of length

Question 18

What occurs in S phase?

Answer 18

duplication of DNA, contains S DNA-damage checkpoint

Question 19

What occurs in G2?

Answer 19

prepares cell for mitosis and also contains G2 DNA-damage checkpoint

Question 20

When do centrioles get duplicated during the cell cycle?

Answer 20

end of G2

Question 21

How many copies of chromosomes are in G1?

Answer 21

one

Question 22

How many copies of chromosomes are in G2?

Answer 22

two (after S phase)

Question 23

What are colchicine, vincritine, and vinblastine?

Answer 23

anti-mitotic agents that inhibit polymerization of microtubules

Question 24

What is the function of taxol?

Answer 24

promotes polymerization and inhibits depolymerization of microtubules

Question 25

What can colchicine be used for?

Answer 25

treat gout by inhibiting expansion of cells in areas of inflammation in the body

Question 26

What cells in our body have more than one nucleus?

Answer 26

cardiac muscle cells are commonly tetraploidy (multi-nucleated)

Question 27

What occurs in prophase?

Answer 27

centrioles migrating to opposite poles of the cells, chromosomes are condensed. nuclear envelope still intact

Question 28

What occurs in prometaphase?

Answer 28

initiated when lamins are phosphorylated and start to disassemble nuclear envelope

Question 29

What occurs in metaphase?

Answer 29

the chromosomes are aligned at the equator of the spindle. the kinetochore microtubules attach sister chromatids to opposite poles of the spindle

Question 30

What occurs in anaphase?

Answer 30

the sister chromatids synchronously separate to form two daughter chromosomes, and each is pulled slowly toward the spindle pole it faces. the kinetochore microtubules get shorter

Question 31

What cleaves the cohesion complexes between chromatids?

Answer 31

seperase

Question 32

How is separase activated?

Answer 32

initiated by APC (anaphase promoting complex)

Question 33

What occurs in telophase?

Answer 33

the two sets of daughter cells are separated and the nuclear envelope reassmebles

Question 34

What occurs in cytokinesis?

Answer 34

the cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell in two to create two daughter cells.

Question 35

What happens when cytokinesis do not occur?

Answer 35

a multi-nucleated cell is made

Question 36

What is the effect of cytochalasin B?

Answer 36

inhibits polymerization of actin microfilaments

Question 37

Are telomerases present in somatic cells?

Answer 37

no, with each round of cell division, part of the genetic info within the telomere region is lost.

Question 38

What is senescence?

Answer 38

the cell is no longer capable of cell division

Question 39

What happens in cancer regarding telomere sequence?

Answer 39

cancer re-expresses telomerase and thus can divide indefinitely

Question 40

What is the difference between necrosis and apoptosis?

Answer 40

apoptosis is more organized and is normal. necrosis is messy, the contents of the cell just bursts, spilling out acidic organelles like lysosomes

Question 41

When phosphatidylserine is translocated to the external layer, it is a signal for what?

Answer 41

marks the cell for apoptosis

Question 42

What are the two types of apoptosis?

Answer 42

intrinsic and extrinsic

Question 43

What might an aggressive tumor do to make it less susceptible to apoptosis?

Answer 43

increase anti-apoptotic factors

Question 44

Both intrinsic and extrinsic pathways converge to what?

Answer 44

activation of caspase

Question 45

How does extrinsic apoptosis initiated?

Answer 45

receptors in the plasma membrane (ie tumor necrosis receptor factor)

Question 46

How does intrinsic apoptosis initiated?

Answer 46

cell injury such as DNA damage, growth factor withdrawal, protein misfolding, etc

Question 47

What is FasL counterattack?

Answer 47

some cancer cells are able to express Fas ligand. they will interact with immune cells and bind to their Fas receptors. this kills off the cells that are supposed to kill cancer cells

Question 48

Explain the role of estrogen in osteoblasts

Answer 48

when estrogen is present, it phosphorylates a pro-apoptotic factor called Bad, which is good. after menopause when estrogen levels decrease, Bad is not being phosphorylated and this leads to osteoporosis (bone cell loss)