Select which principle stage of M phase matches the description on the left.(A) The cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell in two to create two daughters, each with one nucleus.(B) 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, and the spindle poles also move apart; both processes contribute to chromosome segregation.(C) The replicated chromosomes, each consisting of two closely associated sister chromatids, condense. Outside the nucleus, the mitotic spindle assembles between the two centrosomes, which have replicated and moved apart.(D) The two sets of daughter chromosomes arrive at the poles of the spindle and decondense. A new nuclear envelope reassembles around each set, completing the formation of two nuclei and marking the end of mitosis. The division of the cytoplasm begins with contraction of the contractile ring.(E) The chromosomes are aligned at the equator of the spindle, midway between the spindle poles. The kinetochore microtubules attach sister chromatids to opposite poles of the spindle.(F) Starts abruptly with the breakdown of the nuclear envelope. Chromosomes can now attach to spindle microtubules via their kinetochores and undergo active movement.
(A) cytokinesis(B) anaphase(C) prophase(D) telophase(E) metaphase(F) prometaphase
Increased levels of Ran-GTP around mitotic chromatids leads to enhanced microtubule assembly.true or false
true
The pushing force on sister chromatin known as polar wind is created by ____________________ and the pulling force created by __________________ leads to the alignment of chromosomes during metaphase.(A) microtuble treadmilling or kinesins(B) microtuble treadmilling or kinesins
(A) kinesins(B) MT treadmilling
You observe an embryo that has not developed distinct fingers long past the time embryos typically develop fingers, what could be wrong with the embryo?(A) te necrosis pathway is hindered(B) The apoptotic pathway is hindered.(C) there is increased activity of caspases(D) there is increased activity of p53
(B) The apoptotic pathway is hindered.
Cells with a lack of oxygen secrete VEGF, which stimulates ____________.
angiogenesis
There is only one Cdk that triggers all steps of the cell cycle.true or false
false
Which of the following is NOT true in regard to APC/C (Anaphase Promoting Complex)?(A) It stabilizes the interaction between sister chromatids. (B) it functions as ubiquitin ligase, which adds ubiquitin to proteins to target them for destruction (C) it is necessary for the transition to anaphase(D) It's activity is suppressed by misaligned chromosome during metaphase
(A) It stabilizes the interaction between sister chromatids.
Genetic instability accelerates microevolution in cancer progressiontrue or false
true
Which of the following is NOT induced by M-cyclins?(A) phosphorylation of condensin to promote chromosome condensation(B) phosphorylation of MT binding proteins to re-organize MT structures(C) Phosphorylation of p53 to induce cell cycle arrest(D) phosphorylation of nuclear lamina and subsequent breakdown of nuclear membrane
(C) Phosphorylation of p53 to induce cell cycle arrest
Which of the following is TRUE about "Intrinsic apoptosis pathway"?(A) a failure to repair DNA double strand induces p53 phosphorylation and degradation of p53 which leads to the activation of caspases(B) Protein complexes on mitochondrial membrane induces the leakage of cytochrome C, which eventually activates caspases(C) a failure in mitochondrial potential induces a dramatic increase in cytosolic ca2+ [ ] which leads to the denaturation of cellular proteins (D) cell surface receptor recognizes extracellular signal and triggers the assembly of apoptosome to activate caspases
(B) Protein complexes on mitochondrial membrane induces the leakage of cytochrome C, which eventually activates caspases
Cells often escape from cell cycle phases into a quiescent state, called G0 phase. Cells can stay at G0 phase for days to years until a proper signal comes and make a cell to re-enter cell cycle. Which of the followings is TRUE about this process?(A) Mitogens activate cell surface receptors to induce Cyclin transcription, which promote cell cycle re-entry.(B) the cell-cycle re-entry is also called "necrosis"(C) cells in G0 slowly replicate their chromosomes to prepare cell cycle re-entry(D) DNA damage in G2 phase makes cells escape to G0 phase
(A) Mitogens activate cell surface receptors to induce Cyclin transcription, which promote cell cycle re-entry.