The process of cellular reproduction or divisions is a heavily regulated process for a number of different reasons. In the case of the eukaryotic cell there are a number of different checkpoints that a cell must pass before it can continue on. Please explain what those checkpoints are looking for and where those checkpoints are in the cell cycle. If a cell doesn’t pass any of these checkpoints what happens to those cells?

One approach to studying the regulation of cell cycle progression (particularly in an era when genetic and molecular biology manipulations were less readily accomplished in mammalian cells) was to use treatments that induced cells to fuse and then monitor the behavior of the two nuclei in the resulting cell. The figure below depicts data from one such study.  The investigators did preliminary work to produce populations of cells that were synchronized in various stages of the cell cycle (G1, S, or G2 in the examples shown below). They then fused the cells in different combinations and monitored subsequent events in each of the nuclei. For purposes of this question, we will pay particular attention to what occurred in the nucleus that came from the cell in G1. In one experiment (I), cells in the G1 and S phases were fused.  That event caused the nucleus from the G1 cell to very quickly enter the S phase (sooner than it would otherwise have done so).  In contrast, in a second experiment…

During the cell cycle there are three checkpoints. Match each description with the correct checkpoint.                                                                        Requires growth signals and checks there are no mutation in the DNA                                                                        Checks that DNA is properly replicated and that all the organelles and proteins needed for division are present                                                                         Ensures that all the chromosomes are lined up and accounted for A. G1/S B. S/G2 C. G2/M  D. Metaphase/Anaphase E. Anaphase/Telophase

What celluar events/processes are associated with G1,S,G2,and M phases of the cell cycle? With the phases of mitosis? Some example: A. DNA replication B. Beginning of mitosis C. Normal cell growth and function D. Breaksdown of nuclear membrane E.Separation of sister chromatids F.Alignment of chromosomes on the equator of the cell H.Triggering the compaction and condensation of chromosomes I. Attachment of microtubles to kinetochores

A cell can normally halt its progression through the cell cycle at different checkpoints. Which of the following best predicts a reason for a cell to halt its progression through the cell cycle between the G1 and the S phases? A B incorrect attachment of spindle fibers to sister chromatids с insufficient accumulation of nucleotides D mitosis-facilitating enzymes have not been synthesized errors in DNA replication during G1

Which of the following need to be expressed to get past the G1 checkpoint and why? Select one: a. All the answers are correct and needed to progress the cell past the G1 checkpoint by expressing the enzymes necessary for DNA replication. Once these proteins are all expressed, the cell has moved past G1 into S phase. b. Primase because this enzyme is needed for DNA replication moving the cell from G1 to S. c. Cyclins because the accumulation of specific cyclins will turn on CDKs needed to turn on gene expression for proteins involved in DNA replication, moving the cell from G1 to S. d. DNA helicase because this protein is needed for DNA replication (part of S phase). So expression will help progress the cell from G1 to S.

Progression through the cell cycle is dependent on both extra- and intracellular conditions. Consider the following conditions. Indicate which checkpoint (s) responds to that condition.a. The cell is large enough to divide.b. The DNA is completely copied during S phase.c. The cell is receiving positive cues from neighbors.d. The DNA is damaged.e. The cell has enough energy reserves to divide.f. Are all the sister chromatids correctly attached to spindle microtubules?

Please answer question 3