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Chapter 18
| Question | Answer |
|---|---|
| The eukaryotic cell cycle is composed of four phases in the following order | G1; S; G2: M |
| 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 ___ phases(s) | S |
| In a typical cycling mammalian cell, ____ of the cell cycle is spent in interphase | 95% |
| Cell cycle of early embryonic animal cells are unusual because they have | no G1 or G2 |
| 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 | flow cytometer |
| Cells in the quiescent phase of the cell cycle are said to be in the ____ phase | G0 |
| Which of the following represents the amount of DNA in a typical G2 cell | 4n |
| What event takes place during interpahse | Metabolic processes, such as DNA replication, are carried out by the cell |
| Skin fibroblasts near a wound, arrested in G0, are stimulated to enter G1 by _____ growth factor | Platelet-derived |
| 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? | G2 |
| Progression through the cell cycle in the yeast Saccharomyces cerevisiase is regulated by | external signals such as availablity of nutrients and mating factors |
| the G1 checkpoint in budding yeast cells is called | START |
| the G1 checkpoint in animal cells is called | the restriction point |
| the G2 checkpoint prevents entry into _____ if DNA synthesis is incomplete and/or the DNA is damaged | M |
| A scientist notices that cells being grown in culture have ceased to divide. Further investigation demonstrates the cells have abnormally segregated chromsomes. Which checkpoint are these cells likely arrested at? | Spindle assembly checkpoint |
| Maturation promotion factor (MPF), discovered by Masui and Markert, is the factor that | induces entry into meiosis when injected into frog oocytes |
| MPF is a | dimer of Cdk1 and cyclin B |
| MPF is a general regulator of the transition from | G2 to M |
| 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? | Cyclin-dependent kinases |
| Studies on cell cycle mutants in budding and fission yeasts demonstrated that cdc2 and cdc28 both encode a | protein kininase |
| two sea urchin proteins were named cyclin A and B because, during the embryonic cell cycle, they were periodically | synthesized and degraded |
| to become active, Cdk1 must | bind cyclin and be phosphorylated to tyrosine 15 and threonines 14 and 161 |
| Cdks bind to cyclin and are activated by | phosphorylation by Wee1 |
| which cyclin(s) is(are) required to pass the G1 restriction point in animal cells | Cyclin D |
| Passage of animal cells through the cell cycle is regulated primarily by | extracellular growth factors |
| the retinoblastoma protein (Rb) binds to and inhibits | transcription factor E2F |
| growth-factor stimulation of Ras/Raf/MEK/ERK pathway initally stimulates the sunthesis of cyclin | D |
| Cells are restricted to one round of DNA replication per cycle by origin of replication binding proteins called | MCMs |
| To prevent cells with unreplicated DNA from passing through the G2 checkpoint, Chk 1 and Chk2 ____ protein phosphates Cdc25 | Phosphorylate and inhibit |
| p21 inhibits cell cycle progression by binding to and inhibiting | p53 |
| damaged DNA is sensed by a complex of proteins that activate the protein kinase | ATM or ATR |
| the diease ataxia telangiesctasia, which causes nervous system defects and a high frequency of cancer in affected individuals, results from a mutation in the gene for the protein | ATM |
| nuclear envelope breakdown occurs at the | end of prophase |
| entry into mitosis occurs because | Cdk1/Cyclin B (MPF) get activated |
| During prophase, Cdk1/Cyclin B (MPF) directly phosphorylates all following except | APC/C |
| Phosphorylation of the Golgi matrix proteins by Cdk1 during mitosis | mediates breakdown of the Golgi apparatus into vesicles |
| the beginning of anaphase occurs when cohesions, holding the sister chromatids together, are degraded by | separase |
| As the cell enters M phase, the condensins are activated as a result of | phosphorylation by both Cdk1 and Aurora B kinase |
| The DNA region to which proteins bind to form the kinetochore and spindle fibers attach for segregation of the chromsomes is called the | centromere |
| Chromosomes are attached to spindle microtubules by | centromeres |
| polar microtubules | overlap in the center of the spindle |
| during mitosis, the rate of microtubule turnover | increases five- to tenfold |
| during the spindle fiber checkpoint, degradation of _____ allows for separation of the sister chromatids | cohesin |
| the mechanism of cytokinesis in plants involves the formation of the | cell plate |
| the progression from metaphase to anaphase results from | ubiquitin-mediated proteolysis of key regulatory proteins |
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