BIO 592: EXAM 3 STUDY GUIDE QUESTIONS WITH
COMPLETE SOLUTIONS
What parts of the cell cycle are included in interphase? -- Answer ✔✔ G1, G2, and S
phases
What is the G1 phase? -- Answer ✔✔ longest period of the cell cycle in which cells
undergo synthesis of proteins and other macromolecules so that the cell can grow
What is the M phase? -- Answer ✔✔ mitosis and cytokinesis
What is the restrictive point in the cell cycle? -- Answer ✔✔ a point of no return late in
G1 after which the cell will divide regardless of external conditions
What happens to cells that are deprived of their competency to divide? -- Answer ✔✔
they will arrest in the G0 state, in which the cell does not synthesize proteins or grow
What do growth factors do in the cell cycle? -- Answer ✔✔ accelerate G1 in actively
dividing cells and induce G0 to G1 transition
What are stimulators of cell growth? -- Answer ✔✔ primary: GHRH and ghrelin
,secondary: sleep, exercise, hypoglycemia, reduced fatty acids, androgens, and protein
intake
What are inhibitors of cell growth? -- Answer ✔✔ primary: somatostatin and IGF-1
secondary: high glucose, high fatty acids, and estrogen
What does GH deficiency do? -- Answer ✔✔ leads to dwarfism, accompanied by
decreased IGF-1 and IGF-2 levels
What does GH excess do? -- Answer ✔✔ leads to gigantism and acromegaly,
accompanied by higher IGF-1 and IGF-2 levels
Where is IGF-1 mainly produced? -- Answer ✔✔ the liver
How is IGF-1 regulated? -- Answer ✔✔ stimulated by GH and androgens, inhibited by
estrogens and glucocorticoids
What are the actions of IGF-1? -- Answer ✔✔ 1) induces cell proliferation/maturation
and tissue growth
2) inhibits GH secretion
3) mediates most of the growth-promoting and other actions of GH
4) can inhibit apoptosis
5) often called sulfation factor because it induces SO4 incorporation into chondrocytes
, What is the dual-effector hypothesis of GH action? -- Answer ✔✔ GH induces
differentiation of certain precursor cells, which lead to development of IGF-1
responsiveness and increased IGF-1 expression; IGF-1 then causes clonal expansion of
cells, which mature and become adipocytes or bone cells
What type of receptor does IGF-1 bind? -- Answer ✔✔ a tyrosine kinase receptor that
activates MAPK pathways
What is the function of IGF-2 thought to be? -- Answer ✔✔ fetal growth factor that
works through IGF-1 receptors
Where is epidermal growth factor (EGF) produced? -- Answer ✔✔ submaxillary salivary
glands and mammary gland milk
What are the actions of EGF? -- Answer ✔✔ 1) induces cell proliferation/differentiaton
(keratinization) of the epidermis
2) induces tooth eruption, eyelid opening, and enzyme/DNA synthesis in the mucosa of
the digestive tract
3) promotes wound healing
4) involved in neovascularization/angiogenesis
What are the actions of TGF-alpha? -- Answer ✔✔ involved in normal development,
neovascularization, and increasing epidermal generation
What are the actions of TGF-beta? -- Answer ✔✔ 1) inhibits proliferation of many
epithelial and immune cells by arresting cells in G1
COMPLETE SOLUTIONS
What parts of the cell cycle are included in interphase? -- Answer ✔✔ G1, G2, and S
phases
What is the G1 phase? -- Answer ✔✔ longest period of the cell cycle in which cells
undergo synthesis of proteins and other macromolecules so that the cell can grow
What is the M phase? -- Answer ✔✔ mitosis and cytokinesis
What is the restrictive point in the cell cycle? -- Answer ✔✔ a point of no return late in
G1 after which the cell will divide regardless of external conditions
What happens to cells that are deprived of their competency to divide? -- Answer ✔✔
they will arrest in the G0 state, in which the cell does not synthesize proteins or grow
What do growth factors do in the cell cycle? -- Answer ✔✔ accelerate G1 in actively
dividing cells and induce G0 to G1 transition
What are stimulators of cell growth? -- Answer ✔✔ primary: GHRH and ghrelin
,secondary: sleep, exercise, hypoglycemia, reduced fatty acids, androgens, and protein
intake
What are inhibitors of cell growth? -- Answer ✔✔ primary: somatostatin and IGF-1
secondary: high glucose, high fatty acids, and estrogen
What does GH deficiency do? -- Answer ✔✔ leads to dwarfism, accompanied by
decreased IGF-1 and IGF-2 levels
What does GH excess do? -- Answer ✔✔ leads to gigantism and acromegaly,
accompanied by higher IGF-1 and IGF-2 levels
Where is IGF-1 mainly produced? -- Answer ✔✔ the liver
How is IGF-1 regulated? -- Answer ✔✔ stimulated by GH and androgens, inhibited by
estrogens and glucocorticoids
What are the actions of IGF-1? -- Answer ✔✔ 1) induces cell proliferation/maturation
and tissue growth
2) inhibits GH secretion
3) mediates most of the growth-promoting and other actions of GH
4) can inhibit apoptosis
5) often called sulfation factor because it induces SO4 incorporation into chondrocytes
, What is the dual-effector hypothesis of GH action? -- Answer ✔✔ GH induces
differentiation of certain precursor cells, which lead to development of IGF-1
responsiveness and increased IGF-1 expression; IGF-1 then causes clonal expansion of
cells, which mature and become adipocytes or bone cells
What type of receptor does IGF-1 bind? -- Answer ✔✔ a tyrosine kinase receptor that
activates MAPK pathways
What is the function of IGF-2 thought to be? -- Answer ✔✔ fetal growth factor that
works through IGF-1 receptors
Where is epidermal growth factor (EGF) produced? -- Answer ✔✔ submaxillary salivary
glands and mammary gland milk
What are the actions of EGF? -- Answer ✔✔ 1) induces cell proliferation/differentiaton
(keratinization) of the epidermis
2) induces tooth eruption, eyelid opening, and enzyme/DNA synthesis in the mucosa of
the digestive tract
3) promotes wound healing
4) involved in neovascularization/angiogenesis
What are the actions of TGF-alpha? -- Answer ✔✔ involved in normal development,
neovascularization, and increasing epidermal generation
What are the actions of TGF-beta? -- Answer ✔✔ 1) inhibits proliferation of many
epithelial and immune cells by arresting cells in G1
