Which of the following molecules is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active?
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|35. Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active||• Cdk|
|36. Which of the following triggers the cell’s passage past the G2 checkpoint into mitosis||• MPF|
What is the best explanation for the data associated with delta cells?
What is the best explanation for the data associated with delta cells? Delta cells contain no RNA. Delta cells contain no DNA. Delta cells divide in the G1 phase.
Which of the statements is the best explanation for the difference between time spent in S phase by beta and gamma?
Which of the statements is the best explanation for the difference between time spent in S phase by beta and gamma? Gamma contains more DNA than beta. A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus.
Why do most cells in the human body divide infrequently?
Why do most cells in the human body divide infrequently? They have exited the cell cycle and entered G0. The free-energy change for the oxidation of glucose to CO2 and water is -686 kcal/mol, and the free-energy change for the reduction of NAD+ to NADH is +53 kcal/mol.
At what stage of the cell cycle is the cyclin component of MPF destroyed group of answer choices?
In addition to driving the events of M phase, MPF also triggers its own destruction by activating the anaphase -promoting complex/cyclosome (APC/C), a protein complex that causes M cyclins to be destroyed starting in anaphase.
What would you expect to happen if MPF?
What would you expect to happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2? The cells would begin DNA synthesis. The cells would remain arrested in G2. The cells would enter mitosis.
What happens to MPF during mitosis?
One of the pathways activated by MPF is an enzyme that destroys cyclin. So as mitosis gets under way, the enzyme that breaks down cyclin is activated, and levels of cyclin start to drop. As MPF levels drop, so does the activity of the enzyme that destroys cyclin.
Why do neurons and some other specialized?
Why do neurons and some other specialized cells divide infrequently? -They show a drop in MPF concentration. -They no longer have active nuclei.
Which of the following is true of Kinetochores?
Which of the following is true of kinetochores? They interdigitate at the cell’s equator and then move apart, causing the cell to elongate. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow.
In which phase of mitosis do the sister chromatids become daughter chromosomes?
FEEDBACK: Sister chromatids separate and become daughter chromosomes during anaphase of mitosis. During telophase they will be packaged into daughter nuclei and ultimately during cytokinesis they will wind up in separate cells.
Which is the longest of the mitotic stages?
The first and longest phase of mitosis is prophase. During prophase, chromatin condenses into chromosomes, and the nuclear envelope (the membrane surrounding the nucleus) breaks down.
Which cell cycle checkpoint is the most important?
The G2 checkpoint bars entry into the mitotic phase if certain conditions are not met. As with the G1 checkpoint, cell size and protein reserves are assessed. However, the most important role of the G2 checkpoint is to ensure that all of the chromosomes have been accurately replicated without mistakes or damage.
Why do neurons do not divide?
Nerve cells are also known as neurons. There is absence of centrioles in the nerve cells and because of this they are unable to perform mitosis and meiosis and hence these cells do not divide. But nerve cells get longer without dividing and they do not divide during their lifetime.
What is the final result of mitosis in a human?
The daughter cells in mitosis are identical because, unlike the meiotic cell division, where haploid gametes are produced, there is no genetic recombination in mitosis and therefore there is no difference in the cells resulting from mitosis.