Molecular Cell Biology Exam 4 Questions And Answers Well Defined Guaranteed Success.

The number of cells in the different phases of a population can be determined most easily by using a ____ to measure the amount of dna per cell in a large sample of cells. - correct answer Flow cytometer The phase of the cell cycle that corresponds to the interval between mitosis and initiation of dna replication is referred to as the - correct answer g1 phase Progression through the cell cycle in the yeast saccharomyces cerevisiae is regulated by - correct answer external signals such as availability of nutrients and mating factors The g1 checkpoint in animal cells is called - correct answer the restriction point The g2 cell cycle checkpoint detects - correct answer unreplicated or damaged dna Which of the following represents the amount of dna in a typical g2 cell? - correct answer 2n The g2 checkpoint prevents entry into ____ if dna synthesis is incomplete and/or the dna is damaged. - correct answer M Dna content can be found using a method of flow cytometry that can determine 2n or 4n states of cells based on cell counting and fluorescent labeling of dna . which of the following phases would be identified through flow cytometry as 2n? - correct answer Phase only In which of the following cell types do g1 and g2 not take place? - correct answer Early embryonic cells The g1 checkpoint in budding yeast cells is called - correct answer start Cell cycles of early embryonic animal cells are unusual because they have - correct answer no g1 or g2 Cell cycle checkpoints ensure that complete genomes are transmitted to daughter cells. Dna damage checkpoints are found in all of the following phases except - correct answer m phase Cells in the quiescent phase of the cell cycle are said to be in the ___ phase - correct answer g0 You perform an experiment by incubating a radiolabeled nucleotide into the medium of a culture of cells. The cells that take up the radiolabel would be expected to be in what phase of the cell cycle? - correct answer S phase After development, liver cells stop cycling and stay in g1. - correct answer False The eukaryotic cell cycle is composed of four phases in the following order: - correct answer G1 S - correct answer G2 - correct answer M. - correct answer In yeast, START triggers the progression from G1 to S. Which of the following are involved in regulating START? - correct answer All of the above The oocytes in a normal 7-year-old female (prepubertal) would be expected to be arrested in which stage of the cell cycle, until they are hormonally stimulated? - correct answer G2 The length of time it takes for the cells labeled during DNA synthesis to begin to enter mitosis is a good estimate of the length of the _______ phase(s). - correct answer G2 Skin fibroblasts near a wound, arrested in G0, are stimulated to enter G1 by ___ growth factor. - correct answer Platelet-derived Interphase usually consists of G1, S, and G2, but in some cells it consists only of S - correct answer True Which of the following is not a mechanism for regulation of the cell cycle? - correct answer Proteolysis of cdk/cdc protein kinases Cells are restricted to one round of dna replication per cycle by origin of replication binding proteins called - correct answer mcms The passage of a cell through the stages of the cell cycle is controlled by protein kinases that phosphorylate many different proteins at appropriate times. What are these protein kinases called? - correct answer Cyclin-dependent kinases Mpf is a general regulator of the transition from - correct answer g2 to m Two sea urchin proteins were named cyclin a and b because, during the embryonic cell cycle, they were periodically - correct answer synthesized and degraded To prevent cells with unreplicated DNA from passing through the g2 checkpoint, chk1 and chk2 ___ protein phosphatase cdc25. - correct answer Phosphorylate and inhibit P21 inhibits cell cycle progression by binding to and inhibiting - correct answer cyclin-dependent kinases Cdks bind to cyclin and are activated by - correct answer dephosphorylation by cdc25 protein phosphatase Passage of animal cells through the cell cycle is regulated primarily by - correct answer extracellular growth factors. Mpf is a - correct answer dimer of cdk1 and cyclin b In animal cells, cdk2/cyclin a act to drive cells through the restriction point in g1 - correct answer false Damaged dna is sensed by a complex of proteins that activate the protein kinase - correct answer atm or atr The disease ataxia telangiectasia, which causes nervous system defects and a high frequency of cancer in affected individuals, results from a mutation in the gene for the protein - correct answer atm To become active cdk1 must bind cyclin and - correct answer be phosphorylated on threonine 161 and be dephosphorylated on threonine 14 and tyrosine 15 Studies on cell cycle mutants in budding and fission yeasts demonstrated that cdc2 and cdc28 both encode a - correct answer protein kinase ATM recognizes single-stranded DNA breaks and ATR recognizes double-stranded DNA breaks. - correct answer False Which cyclin(s) is(are) required to pass the G1 restriction point in animal cells? - correct answer Cyclin D The retinoblastoma protein (Rb) binds to and inhibits - correct answer transcription factor E2F. Maturation promotion factor (MPF), discovered by Masui and Markert, is the factor that - correct answer induces entry into meiosis when injected into frog oocytes. Rb is a tumor suppressor protein that acts by inhibiting phosphorylation of Cdk - correct answer False Rb is a member of the family of tumor suppressor genes. - correct answer True Growth-factor stimulation of the Ras/Raf/MEK/ERK pathway initially stimulates the synthesis of - correct answer cyclin D Fibroblasts are stimulated to exit g0 and proliferate by __ growth factor platelet-derived When stem cells of the intestinal epithelium and epidermis divide, they give rise to two different cells: one stem cell and one __ cell. Transit-amplifying Using approaches similar to those of takahashi and yamanaka, scientists have now reprogrammed adult fibroblasts to become - correct answer heart muscle cells. If reintroduced into early embryos, embryonic stem cells can give rise to cells in all tissues of a mouse. - correct answer True Hematopoietic stem cells can give rise to - correct answer all blood cells and macrophages Which of the following are the three core transcription factors that can reprogram adult somatic cells into induced pluripotent cells? - correct answer Sox2, oct4, and nanog Goblet cells and enteroendocrine cells have the same stem cells as absorptive epithelial cells. - correct answer True Liver cell injury induces proliferation of liver stem cells. - correct answer False Of the offspring that result from the reproductive cloning of mamals by somatic nuclear transfer, __ % are viable - correct answer 1-2 The clinical application of adult stem cells is limited by difficulties in isolating and culturing the appropriate stem cell populations. - correct answer True Most cells in adult animals are in the __ stage of the cell cycle - correct answer g0 Each of the three cell types in the adult intestinal epithelium is derived from a different stem cell - correct answer false Which of the following signaling pathways is not important to stem cell physiology? - correct answer Bax A hematopoietic stem cell may give rise to which of the following differentiated cells? - correct answer All of the above Intestinal stem cells may give rise to all of the following terminally differentiated cell types in the intestinal epithelium except __ cells. - correct answer Transit-amplifying Mammalian embryonic stem cells are cultured from cells taken from - correct answer the inner cell mass. Early experiments by takahashi and yamanaka showed that a set of four genes introduced by retroviral expression are capable of transforming somatic cells into induced pluripotent stem cells. The four proteins encoded by these genes were all - correct answer transcription factors In 2006, takahashi and yamanaka demonstrated that somatic cells can be reprogrammed or converted into induced pluripotent stem cells. Subsequent studies in __ showed that these cells, like embryonic stem cells, are capable of differentiating into virtually all cells. - correct answer Mice Which of the following adult cell types is arrested in g0? - correct answer All of the above Vegf is secreted by - correct answer cells deprived of oxygen Most differentiated cell types do not themselves proliferate, but they can be replaced by the proliferation of stem cells. - correct answer True Which of the following is not a key property of stem cells in tissues? - correct answer Dividing