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GRE Cell Biology: Cell Cycle

Subjects : gre, science, biology
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Begins to form in the cytoplasm during prophase. Consists of fibers made of microtubules - centrosomes and associated proteins. While it assembles - other microtubules of the cytoskeleton partially disassemble - probably providing the material used t






2. A critical control point where stop and go-ahead signals can regulate the cycle. Signals often report whether crucial cellular processes up to that point have been completed correctly and thus whether or not the cell cycle should proceed. Also regis






3. A cell'S endowment of DNA






4. Abnormal cells remain at the original sight after transformation (the process that converts normal cells to cancer cells). Usually do not cause serious problems and can be removed by surgery.






5. Reproductive cells--sperm and egg cells. Have half as many chromosomes as somatic cells. Have one set of 23 chromosomes in humans.






6. Second phase of mitosis. The nuclear envelope fragments. The microtubules of the spindle can now invade the nuclear area and interact with the chromosome - which have become even more condensed. Microtubules extend from each centrosome towards the m






7. The narrow 'waist' at a specialized region where two chromatids are most closely attached.






8. A type of unicellular protist. Mostly marine plankton.






9. A type of unicellular protist.






10. A phenomenon in which crowded cells stop dividing. When a cell population reaches a certain density - the availability of nutrients becomes insufficient to allow continued cell growth and division. Not exhibited in cancer cells.






11. Second phase of interphase. The phase in which chromosomes are duplicated. Occurs between G1 and G2 phase.






12. Experiments have demonstrated that the sequential events of the cell cycle are directed by this cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle.






13. G1 phase (first gap) - S phase ('Synthesis') - and G2 phase (second gap). During all phases - the cell grows by producing proteins and cytoplasmic organelles such as mitochondria and the ER.






14. Forms during telophase in plant cells in preparation for cytokinesis. Formed by vesicles derived from the Golgi apparatus moving along microtubules to the middle of the cell and coalescing. Enlarges until its surrounding membrane fuses with the plas






15. Fourth phase of mitosis. The shortest stage of mitosis. Begins with the two sister chromatids of each pair being pulled apart--each becoming a full fledged chromosome. The two liberated chromosomes begin moving towards opposite ends of the cell - as






16. A part of the cell cycle. Often accounts for about 90% of the cell cycle. In this phase - the cell grows and copies its chromosomes in preparation for cell division.






17. A protein that promotes mitosis. Often called a growth factor though.






18. All body cells except the reproductive ones. The nuclei of human somatic cells contain 46 chromosomes made up of two sets of 23 - one set inherited from each parent.






19. Could be an example of cases where ancestral mechanisms have remained relatively unchanged over evolutionary time. The nuclear envelope remains intact during cell division. The microtubules for a spindle within the nucleus and then separate the chrom






20. 'Maturation-promoting Factor' or 'M-Phase-promoting Factor' Example of cell cycle control molecules.The cyclin-Cdk complex that was first discovered. Triggers the cells passage past the G2 checkpoint into M phase by phosphorylating a variety of prot






21. First phase of interphase. Major period of cell growth. Most variable length in length for all the phases in different types of cells.






22. A part of the cell cycle - which includes both mitosis and cytokinesis.






23. Where the DNA molecules are packaged into. Each eukaryotic species has a characteristic number of chromosomes in each cell nucleus. Each single chromosome contains one very long - linear DNA molecule that carries several hundred to a few thousand gen






24. Prophase - prometaphase - metaphase - anaphase - and telophase.






25. Usually immediately follows mitosis. The division of the cytoplasm of a cell-where one cell becomes two - each genetically equivalent to the parent cell. Involves the formation of a cleavage furrow - which pinches the cell in two.






26. The spindle microtubules that attach to the kinetochores during prometaphase. During anaphase - the kinetochore microtubules shorten at their kinetochore end - not their spindle pore ends. Experimental evidence supports the hypothesis that the prima






27. An imaginary plane that is equidistant between the spindle'S two poles where the chromosome'S centromeres lie during metaphase.






28. Could be an example of cases where ancestral mechanisms have remained relatively unchanged over evolutionary time. The nuclear envelope remains intact during cell division and the chromosomes attach to the nuclear envelope. Microtubules pass through






29. Exhibited by most animal cells. In order to divide - the cells must be attached to a substratum like the extracellular matrix of a tissue. Experiments suggest that anchorage is signaled to the cell cycle control system via pathways involving plasma m






30. A type of cell division that prokaryotes (bacteria and archaea) undergo to reproduce.






31. Each duplicated chromosome has two sister chromatids. Each contain an identical DNA molecule and are initially attached by adhesive proteins all along their lengths. Are most closely attached to one another at the centromere.






32. What eukaryotic chromosomes are made of. A complex of DNA and associated protein molecules.






33. A variation of cell division in which you produce gametes - which yields nonidentical daughter cells that have only one set of chromosomes - thus half as many chromosomes as the parent cell. Only occurs in the gonads (ovaries and testes).






34. The life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells.






35. The nondividing state in the cell cycle. If a cell does not receive a go-ahead signal in the G1 phase - it will exit the cycle and switch into this state. In the human body - fully formed - mature nerve and muscle cells are in this state and never di






36. A radial array of short microtubules that extend from each centrosome. (Do not connect to kinetochore.)






37. Cyclin-Dependent Kinases.Enzymes that activate or inactive other proteins by phosphorylating them. Particular ones give the go-ahead signals at the G1 and G2 checkpoints. Present at a constant concentration in the growing cell - but much of the time






38. Proteins that get their name from their cyclically fluctuating concentration in the cell. Activate kinases when the attach to them.






39. The process by which cytokinesis occurs in animal cells. The first sign of this beginning is the appearance of a cleavage furrow.






40. A specific place on the bacterial chromosome where the process of cell division begins by DNA replication - producing two origins. As the chromosome begins to replicate - one origin moves rapidly toward the opposite end of the cell.






41. A nonmembranous organelle that functions throughout the cell cycle to organize the cell'S microtubules. A pair of centrioles is located at the center of the centrosome - but the centrioles are not essential for cell division (most centrosomes of plan






42. Third phase of mitosis. The longest stage of mitosis (~20mins). The centrosome are now at opposite ends of the cell. The chromosomes convene on the metaphase plate. For each chromosome - the kinetochores of the sister chromatids are attached to kinet






43. A shallow groove in the cell surface near the old metaphase plate. Indicates the beginning of cleavage during cytokinesis. On the cytoplasmic side of the furrow is a contractile ring of actin microfilaments associated with molecules of the protein my






44. Made by platelets (blood cells). Required for the division of fibroblasts (a type of connective tissue cell that synthesizes the ECM and collagen and is important in wound healing): fibroblasts have PDGF receptors that are tyrosine kinases on their p






45. The last phase of interphase - occurring after the S phase. Cell continues to grow but also completes preparations for cell division. In this phase - chromosomes that duplicated during S phase cannot be seen individually because they have not condens






46. Abnormal cancer cells that become invasive enough to impair the functions or one or more organs form this. An individual with a malignant tumor is said to have cancer. Abnormalities in cells of malignant tumors: they may have unusual number of chromo






47. Most genes are carried on a single bacterial chromosome that consists of a circular DNA molecule and associated proteins. The process begins when the DNA of the bacterial chromosome begins to replicate at the origin of replication - producing two or






48. A structure of proteins associated with specific sections of chromosomal DNA at the centromere. Each of the two sister chromatids has one. The chromosome'S two kinetochores face in opposite directions and during prometaphase - some of the spindle mic






49. A specific protein release by certain cells that stimulates other cells to divide.






50. Two main types: kinases and cyclins.