Cell Cycle

Question 1

What part of the cell cycle is the cell in most of the time

Answer 1

Interphase (G1, S, G2)

Question 2

G1

Answer 2

Active metabolism and accumulation of building blocks and energy

Question 3

S phase

Answer 3

Synthesis of DNA: DNA replication occurs-each DNA molecule produce identical copy; centrosome is duplicated

Question 4

G2

Answer 4

Active metabolism and protein synthesis; duplication of organization

Question 5

Cells undergo normal growth and metabolism while also preparing for cell division

Answer 5

Interphase

Question 6

Prophase

Answer 6

• chromosomes and condense and become visible
• spindle fibers emerge from the centrosomes
• nuclear envelope breaks down
• nucleus disappears

Question 7

Prometaphase

Answer 7

• chromosomes continue to condense
• kinetochores appear at the centromeres
• mitotic spindle microtubules attach to kinetochores
• centrosomes move toward opposite poles

Question 8

Metaphase

Answer 8

• mitotic spindle is fully developed, centrosomes are opposite poles of the cell
• chromosomes are lined up at the metaphase plate
• each sister chromatid is attached to a spindle fiber originatin from opposite poles

Question 9

Anaphase

Answer 9

• cohesion proteins binding the sister chromatids together break down
• sister chromatids (now called chromosomes) are pulled toward opposite poles
• non-kinetechore spindle fibers lengthen, elongating the cell

Question 10

Telophase

Answer 10

• chromosomes arrive at opposite poles and begin to decondense
• nuclear envelope material surrounds each set of chromosomes
• the mitotic spindle breaks down

Question 11

Cytokinesis

Answer 11

• animal cells: a cleavage furrow separates the daughter cells
• plant cells: a cell plate separates the daughter cells

Question 12

Majority of the cells in th human body have withdrawn from the cell cycle into:

Answer 12

• A terminally differentiated state (neurons, myocytes)-DO NOT renter the cell cycle
• a reversible quiescent G0 phase (stem cells, glial cells)-capable to return to the cell cycle

Question 13

G0-rest in

Answer 13

A period in the cell cycle in which cells exist in a quiescent state

Question 14

Quiescent state

Answer 14

The cell is neither dividing not preparing to divide

Question 15

G2 checkpoint

Answer 15

Check for:

• cell size
• accurate DNA replication

Question 16

M checkpoint

Answer 16

Check for:

-chromosome attachment to the spindle

Question 17

G1 checkpoint (restriction)

Answer 17

Check for:

• cell size
• nutrients
• growth factors
• DNA damage

Question 18

What is the point of the regulation at internal checkpoints?

Answer 18

Avoid producing mutated cells

Question 19

Regulatory molecules in the control of the cell cycle

Answer 19

1. Positive regulation

2. Negative regulation

Question 20

Positive regulation

Answer 20

Cycling and Cdk

Question 21

Cyclins and Cdks

Answer 21

• changes of different cyclins throughout the cell cylce

- direct correlation between cycling accumulation and the three major cell cycle checkpoints

Question 22

What happens to the cylin following each checkpoint

Answer 22

Sharp decline of cyclin levels following each checkpoint as cyclin is degraded by cytoplasmic enzymes

Question 23

When are cyclins active?

Answer 23

Only when bond to the respective cyclin-dependent kinase (CDK)

Question 24

Rib, p53, p21

Answer 24

Negative regulation

Question 25

What prevents initiation of the cell cycle in G1 phase

Answer 25

Rib-retinoblastoma protein

Question 26

What is p53?

Answer 26

Transcriptional repressor

Question 27

What does p53 do?

Answer 27

Has the ability to repress transcription and to promote apoptosis through direct interaction with apoptotic regulators in the cytosol

Question 28

What does p53 induce?

Answer 28

Cell cycle arrest

Question 29

What does p53 check for?

Answer 29

DNA damage, cell cycle abnormalities, hypoxia

Question 30

What prevents cell cycle progression

Answer 30

p21

Question 31

How does p21 prevent cell-cycle progression?

Answer 31

- by inhibiting the activity of cyclin E-associated CDK2 | - therefore preventing E2F-mediated gene transcription and cell cycle progression

Question 32

External stimuli that cause cells to proliferate (return to G1 if in G0)

Answer 32

Mitogens

Question 33

Mitogen sources

Answer 33

- can be provided by extracellular matrix (integrins) | - can be extracellular signals from more distant sources

Question 34

Cell-matrix contact of mitogens

Answer 34

Mitogenic

Question 35

Cell-to-cell contact

Answer 35

Antimitogenic (contact inhibition) | -no more space, stop dividing

Question 36

Extracellular signals from more distant sources of mitogens

Answer 36

- growth factors | - cytokines

Question 37

Mitogen growth factors

Answer 37

- EGF - VEGF - NGF - FGF Tissue/cell specific

Question 38

Mitogen cytokines

Answer 38

- IL-1 | - IL-6

Question 39

Platelet derived growth factor (PDGF)

Answer 39

Present in the a-granules of platelets from which it is releases during activation- participates in wound healing

Question 40

What participates in wound healing

Answer 40

Platelet derived growth factor (PDGF)

Question 41

Epidermal growth factors (EGF)

Answer 41

Stimulates the proliferation of epithelial cells and some other cells. It acts primarily in its tissues of origin (local)

Question 42

Fibroblast growth factors (FGFs)

Answer 42

Are a family of at least 22 proteins that act on four different tyrosine kinase receptors. They stimulate notionally fibroblasts by also many other cells

Question 43

Insulin-like growth factor 1 (IGF-1)

Answer 43

Releases from the liver in response to growth hormone

Question 44

Vascular endothelial growth factor (VEGF)

Answer 44

Produced by cells that stimulates vasculogenesis and angiogenesis (new blood vessel formation) wet AMD

Question 45

Nerve growth factor (NGF)

Answer 45

Stimulates the growth and differentiation (but not mitosis) of postganglionic sympathetic neurons

Question 46

Neoplasms

Answer 46

Abnormal uncontrolled cell cylce over period of time can lead to the development of this

Question 47

Group of cells that have undergone unregulated growth and will often form a mass or lump, but may be distributed diffusely

Answer 47

Tumors

Question 48

6 hallmarks of cancer, which are required to produce a malignant tumor:

Answer 48

- cell growth and division absent the proper signals - continuous growth and division even given contrary signals - avoidance of programmed cell death - limitless number of cell divisions - promoting blood vessel construction - invasion of tissue and formation of metastases

Question 49

Mutated normal genes that encode positive cell cycle regulators that cause a cell to become cancerous

Answer 49

Oncogenes

Question 50

Genes that encode for negative regulator proteins that will suppress uncontrolled cell division

Answer 50

Tumor suppressor genes | -put a break on the cell cycle if possible

Question 51

Example of tumor suppressor genes

Answer 51

Rib; p53; p21

Question 52

Mutated p53

Answer 52

Cell cycle continues instead of programmed cell death