Exam #1: Cell Biology VII

Question 1

When is the nucleolus best viewed?

Answer 1

In a euchromatic cell

Question 2

NO

Answer 2

• Nuclear Organizer
• Lightly stained
• Contains DNA that is used to transcribe mRNA that is used for the formation of ribosomal subunits (rRNA)

Question 3

PF

Answer 3

• Pars Fibrosa

- Early packaging of ribosomal subunits

Question 4

PG

Answer 4

• Pars Granulosa

- Maturing of ribosomal subunits

Question 5

NAC

Answer 5

Nucleolus Associated Chromatin

Question 6

Nucleostemin

Answer 6

• p53 binding protein
• Found in undifferentiated cells
• Decreases as cells become more differentiated

Question 7

What is the relationship between nucleostemin & cancer?

Answer 7

• Nucleostemin binds p53
• Blocks DNA damage checkpoint
• Allows progression through the cell cycle unchecked

Question 8

What are the steps of the cell cycle?

Answer 8

1) G1
2) S
3) G2
4) M

Question 9

What is the S-phase checkpoint?

Answer 9

DNA Damage

Question 10

What is the G2 checkpoint?

Answer 10

DNA Damage

Question 11

G0

Answer 11

• Normal resting cell state

- Long-lived cells spend a long time in this phase

Question 12

Centriole Duplication

Answer 12

• Starts in G1
• Continues in S
• Completed in G2 so there are two pairs of centrioles

Question 13

What are the important drivers of the cell cycle?

Answer 13

Cyclins

Question 14

When does the replication of chromosomes occur?

Answer 14

S-phase

Question 15

In G1 how many chromosome are there?

Answer 15

23

Question 16

In G2 how many chromosomes are there?

Answer 16

46 (referred to as chromatids)

Question 17

What happens in mitosis?

Answer 17

Separation of homologous chromatids

Question 18

What are the stages of mitosis?

Answer 18

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

Question 19

What is the functional outcome of mitosis?

Answer 19

• Transition from one nucleus to two nuclei
• Mitosis alone does not include cell division
• It is normal to have cells that are tetraploid

Question 20

What is an example of a normal tetraploid cell?

Answer 20

Cardiac muscle cell

Question 21

Prohpase

Answer 21

• Nuclear envelope intact
• Centrioles migrate to opposite sides of cell
• Chromosomes condensed

Question 22

Prometaphase

Answer 22

• Initiated by phosphorylation of lamins & disassembly of nuclear envelope

Question 23

What drugs inhibit mitosis, and how?

Answer 23

• Colchicine (Gout)
• Vincristine (Cancer)
• Vinblastine (Cancer)

Inhibit polymerization of microtubules

Question 24

What drug promotes polymerization & inhibits depolymerization of microtubules?

Answer 24

Taxol

Question 25

Metaphase

Answer 25

Chromatids aligned in the center of the cell

Question 26

Anaphase

Answer 26

Sister chromatids pulled to opposite ends if the cell

Question 27

What needs to occur for separation of the chromatids to occur?

Answer 27

- Cohesion complexes must be digested | - Initiated by APC

Question 28

APC

Answer 28

- Anaphase promoting complex | - Activated Separase

Question 29

Separase

Answer 29

- Enzyme that cleaves cohesion complexes | - Allows for separation of chromatids in anaphase

Question 30

Telophase

Answer 30

- Chromatids at opposite sides of the cell | - Nuclear envelope reassembles

Question 31

What types of filaments interact at the cleavage furrow for cytokinesis?

Answer 31

Actin & Myosin

Question 32

Cytokinesis

Answer 32

Contraction of actin & myosin at the contractile ring causes a narrowing & pinching off of the single cell to make two cell

Question 33

Cytochalasin B

Answer 33

Inhibits polymerization of actin microfilaments & thereby prevent cytokinesis

Question 34

Telomeres

Answer 34

- Sequence of DNA on the end of the chromosome - Some lost with each round of somatic cell division - Germ-cells do not lose

Question 35

Telomerase

Answer 35

Enzyme that maintains telomere length

Question 36

What is the relationship between telomerase & cancer?

Answer 36

Cancer cells express telomerase & therefore can divide indefinitely

Question 37

Necrosis

Answer 37

- Violent mechanism of cell death - Cell fragments/ explodes & exposes antigenic material to immune system - Causes an immune response/ inflammation

Question 38

Apoptosis

Answer 38

- Programmed Cell Death | - Eliminates itself non-violently without activation of inflammatory response

Question 39

What eliminates apoptotic bodies?

Answer 39

Phagocytosis

Question 40

What side of the cell membrane is phosphatidylserine normally located on, and how is this related to apoptosis?

Answer 40

- Normally on the cytosolic monolayer | - Flipping to the extracellular monolayer marks the cell of apoptosis

Question 41

Intrinsic Apoptosis Pathway

Answer 41

- Involved in cell injury - Pro-apoptotic factors triggered that influence the mitochondria - Cytochrome C released

Question 42

Extrinsic Apoptosis Pathway

Answer 42

- Receptor on the cell membrane activated (death receptor | - E.g. TNFR & TNF ligand, Fas & Fas Ligand on Cytotoxic T- Lymphocyte

Question 43

FasL Counterattack

Answer 43

- Cells becoming cancerous express Fas Ligand - Interact with immune cell, FasR - Therefore, kill off cells that were intended to kill them

Question 44

Estrogen & Anti-apoptotic effects

Answer 44

- Estrogen decreases after menopause - Normally phosphorylates Bad & inactivates it - Bad-P does not kill osteoblasts - Non-phosphorylated Bad kills osteoblasts - Leads to a decrease of osteoblasts & osteoporosis