Scientists studying the cell cycle measured the DNA content of non-dividing mamm
ID: 85082 • Letter: S
Question
Scientists studying the cell cycle measured the DNA content of non-dividing mammalian cells and determined that the diploid amount per cell was 3. They then measured a cycling cell population and the amount of DNA ranged from 3.5 to 3.5. These cells are most likely in which of the following phases? a. G1 b. G2 c. G1 or G2 d. S e. metaphase Organisms can regulate their cell number by a. signaling through MAPK pathways for progression from S1 to the S phase of the cell cycle b. signaling for the survival of cells through the PDK/PKB-mediated pathways. c. signaling for apoptosis by use of the F as. d. both a and b. e. all of the above. Which of the following takes place during prophase prophase/prometephase of mitosis in an animal cell? a. Chromosomes begin to condense. b. The chromosomes align at equators between spindle poles. c. Sister chromatids remain attached to each other at the centromere and move toward the pole as a unit. d. Contractile rings promote the process of cytokinesis. To identify cellular components involved in the cell cycle, investigators used a screen of fission each yeast S. Below are the phenotypes the investigators found with their yeast cells. Predict the phenotype of each of the following cells. Wild-type S-pombe _____ mutant that overexpresses cdc25 _____ mutant that is deleted of a gene encoding anaphase inhibitor securin _____ mutant deleted of gene encoding CDK _____ mutant 12 (above) transformed with a plasmid encoding wild-type CDK _____ mutant 12 (above) transformed with a plasmid encoding CDK with Tyr 15 mutated to Phe (Phe can't be phosphorylated) _____ mutant cell that has been unable to replicate all its DNA _______ mutant with a knocked out Mad2 _____ mutant that contains a dominant-negative APCExplanation / Answer
Answer 7) The correct answer is option (d).
The diploid amount per cell was 3 picograms. When scientists measured a cycling cell population, the amount of DNA ranged from 3.3 to 5.5 picograms. You must be knowing that during S phase, the replication of DNA takes place.. The cell entered the S phase are at the early stage and just started duplication has 3.3 picograms amount of DNA, the cells at the later stage of S phase has 5.5 picograms amount of DNA. Therefore, the cell population was in S phase where the duplication of the amount of DNA was occurring
Answer 8) The correct answer is option (d).
P13K/PKB mediated pathway is commonly known as Akt pathway. The growth factors activate P13K which causes the production of the lipid PIP3, which recruits PKB, PDK1 and PDK2. PDK1 and PDK2 undergo phosphorylation and activated PKB phosphorylates a number of substrate proteins. These substrate proteins promote the activation of Cdk2 and G1/S transition.
Raf-MEK-ERK cascade is responsible for the activation of transcription factors that regulate the genes required for G1/S progression. ERK is the best characterized MAPK and the Raf-MEK-ERK cascade represents MAPK signaling pathway.
Answer 9) The correct answer is option (a).
Chromosomes begin to condense at the prophase stage.
The sister chromatids remain attached to each other at the centromere and move towards the pole as a unit at the Anaphase I stage of meiosis I. The the chromosomes align at the equators between poles during the beginning of metaphase stage.
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