Cell VII

Question 1

True or false: the nucleolus is membrane bound?

Answer 1

False

Question 2

How many nucleoli are usually observed in a typical nucleus?

Answer 2

1-2

Question 3

What is the size of the nucleoli proportional to?

Answer 3

Amount of protein synthesis in the cell

Question 4

What is the nucleoli particularly rich in (2)?

Answer 4

rRNA

Protein from free polyribosomes

Question 5

What are the three components of the nucleoli?

Answer 5

1. Nucleolar organizer DNA (sequence of bases that code for rRNA
2. Pars fibrosa (new, naked rRNA)
3. Part granulosa (maturing subunits of ribosomes)

Question 6

How does the nucleolar organizer appear in the nucleolus (using EM)?

Answer 6

lighter, amorphous patches that is surrounded by darker patches

Question 7

What does the pars fibrosis look like at the EM level?

Answer 7

encircles the nucleolar organizer, but is darker and more granulated

Question 8

Where is the pars granuloso located in the nucleolus? What does it look like/

Answer 8

Center of the nucleolus, away from the nucleolar organizer. Granulated and darker than the NO

Question 9

How does the nucleaolar associated chromatin appear under EM?

Answer 9

VERY dark area on the periphery of the nucleolus

Question 10

What is nucleostemin? What happens to it as cells develop?

Answer 10

p53 binding protein found in UNdifferentiated cells.

Decreases as cells become differentiated

Question 11

How is nucleostemin implicated in CA?

Answer 11

Its presence may play a role in unchecked proliferation of CA cells, since p53 is bound

Question 12

What are the four stages of the cell cycle?

Answer 12

G1
S
G2
M

Question 13

What is the most variable stage in the cell cycle?

Answer 13

G1 (9-12 hrs)

Question 14

When does centriole duplication occur in the cell cycle?

Answer 14

S phase

Question 15

True or false: DNA replication can occur without cytokinesis?

Answer 15

True–leads to polyploid cells

Question 16

Where are the checkpoints in the cell cycle?

Answer 16

G1
S
G2

Question 17

When is centriole replication complete?

Answer 17

Before or at the beginning of G2

Question 18

What does the checkpoint at G2 check for/

Answer 18

Unreplicated DNA (replication forks)

DNA damage

Question 19

What are two examples of cells in G0?

Answer 19

Striated muscle cells

Most neurons

Question 20

What drives the cell cycle?

Answer 20

CDK and cyclins

Question 21

In what part of mitosis do chromatids condense?

Answer 21

Prophase

Question 22

In what part of mitosisdoes centrioles begin to migrate to opposite ends of the cell?

Answer 22

Prophase

Question 23

When is prometaphase initiated?

Answer 23

When the nuclear lamins are phosphorylated and disassociate

Question 24

What is the action of drugs like colchicine, vincristine, and vinblastine?

Answer 24

Inhibit polymerization of microtubules needed for centrioles

Question 25

How is colchicine used to treat gout?

Answer 25

Prevent immune cells from entering joints (which is microtubule dependent)

Question 26

What is the effect of Taxol?

Answer 26

Inhibits depolymerization of microtubules

Question 27

In what part of mitosis are chromatids aligned in the center of the cell?

Answer 27

Metaphase

Question 28

In what part of mitosis does colchicine arrest dividing cells?

Answer 28

at metaphase

Question 29

In what phase of mitosis does separation of chromatids occur?

Answer 29

Anaphase

Question 30

In what part of mitosis do nucleoli disappear?

Answer 30

early prometaphase

Question 31

What is the protein that connects chromatids together?

Answer 31

Cohesin

Question 32

What breaks cohesin (2)?

Answer 32

Anaphase promoting complex activates Separase

Question 33

Why would you expect the cytoplasm to be eosinophilic in cells that are active in transcription?

Answer 33

Increased rER to synthesize protein.

Question 34

What are the checkpoints in telophase?

Answer 34

Spindle assembly | Chromosome segregation

Question 35

True or false: organelles such as mitochondria and Golgi are evenly separated with cytokinesis?

Answer 35

False-daughter cell may be shorted

Question 36

What proteins are necessary to initiate the cleavage furrow?

Answer 36

Actin and myosin

Question 37

How does cytochalasin B exert its effects on mitotic division/

Answer 37

Inhibits polymerization of actin microfilaments that divide the cell

Question 38

What is the consequence of the lack of telomerase in somatic cells?

Answer 38

Telomers shorten, leading to senescence

Question 39

What two types of cells normally express telomerase?

Answer 39

Stem cells and germinal cells

Question 40

What are the two main mechanisms of cell death/

Answer 40

Necrosis | Apoptosis

Question 41

What is the difference between necrosis and apoptosis?

Answer 41

Immune response is present in necrosis

Question 42

What is phosphatidylserine's role in apoptosis?

Answer 42

this phospholipid is normally located in the CYTOSOLIC lipid monolayer. When phosphatidylserine is translocated to the extracellular lipid monolayer, it marks the cell as dead. This marker signals neighboring cells to phagocytose and digest the dead cell.

Question 43

What are the two pathways that initiate apoptosis?

Answer 43

Extrinsic and intrinsic

Question 44

What are the two extrisic receptors that activate apoptosis?

Answer 44

Tumor necrosis factor +TNF receptor | Fas ligand + fas receptor

Question 45

What cells express the ligand, Fas, that activate the Fas receptor on cell destined for apoptosis?

Answer 45

Cytotoxic T cell

Question 46

What is the first major step in the intrinsic apoptosis pathway, after the cell has signalled that it is injured?

Answer 46

Mitochondria releases cytochrome C

Question 47

What is the action of cytochrome C when released into the cytoplasm?

Answer 47

Activated caspase 8

Question 48

What is the FasL counter attack?

Answer 48

When tumor cells express the Fas ligand-which is normally found only on cytotoxic T cells- and caused apoptosis of cytotoxic T cells

Question 49

What is the function of the "Bad" apoptotic factor?

Answer 49

Bad is phosphorylated in the presence of estrogen, but if estrogen levels decrease (menopause), then it will not be phosphorylated, and will trigger the death of osteoblasts (osteopenia)

Question 50

Where is apoptosis needed in development?

Answer 50

1. Form spaces between fingers 2. Connection b/t uterus and vagina 3. Break anal and choanal membranes 4. Immune cells 5.