Concept explainers
To review:
The effects of exposing eukaryotic cells to radioactive thymidine during the S or synthesis phase of interphase, on sister chromatids of the duplicated chromosome at metaphase of the mitosis, after the second round of DNA (deoxyribonucleic acid) replication in a medium free of radioactive labels.
Introduction:
DNA of eukaryotic chromosomes replicate semi-conservatively. This was illustrated by labeling the cells with radioactive thymidine during the S-phase and then grown in the absence of radioactive thymidine. The cell cycle was then studied. The cell cycle consists of interphase and mitotic phase. DNA is synthesized during the S-phase of interphase whereas the mitotic phase is the divisional phase and consists of prophase, metaphase, anaphase, and telophase.
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Biology: The Dynamic Science (MindTap Course List)
- The same chromosome can look very different depending on when in meiosis it is observed. Explain fully why this is so and also why the chromosome is less condensed during some parts of the cell cycle? How many DNA molecules does each chromosome contain at the beginning of Prophase I? Use the following terms in your explanation: chromatin, histone, chromatid, centromere.arrow_forwardNormal events in mitosis gives rise to daughter cells with exactly the same chromosome number and genetic material. What may be expected to happen chromosomally and genetically to: 1. an unfertilized egg that undergoes mitosis, but fails to undergo cytokinesis? 2. a cell with a chromosome that lost its centromere? 3. a cell with a chromosome that contains two centromeres?arrow_forwardThe drug chloral hydrate prevents elongation of microtubules by preventing the addition of new subunits to the growing end. During which stage of mitosis would chloral hydrate be most harmful?arrow_forward
- 1) Examine the picture of an onion root tip with cells in various stages of the cell cycle. A student claims that interphase is the longest stage of the cell cycle. Another student claims that mitosis is the longest stage. Using evidence from the photo, determine which student is correct and why. A) Mitosis is the longest stage because anaphase requires more time to separate chromatids. B) Interphase is the longest stage because chromosomes are visible in the majority of the cells. C) Mitosis is the longest stage because the majority of the cells in the photo are replicating their DNA. D) Interphase is the longest stage because the majority of the cells in the photo have uncondensed chromatin and are not dividing. Not Gradedarrow_forwardIn the mitosis experiment, in what stage were most of the onion root tip cells in? Based on what you know about cell cycle division, what does this imply about the life span of a cell? Were there any stages of the cell cycle that you did not observe? How can you explain this using evidence from the cell cycle?arrow_forwardThe phases of mitosis are shown in Figure 6.4. Mitosis is the type of nuclear division that occurs when an animal or plant grows larger and when injury heals. Two daughter cells result because there is only one round of division, and it keeps the chromosome number constant (same as the parent cell). The prophase cell in Figure 6.4 has the same number of chromosomes as the telophase nuclei in Figure 6.4. Explain the different appearance of the chromosomes.arrow_forward
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- Please help Place the images of the cell division in the right order and label them a)  What is the final product of this type of cell division? Indicate the number of dauahter cells, the TYPE OF CELLS (somatic cells? sex cells? other?), where in the body this process takes place, whether they are genetically diverse pridentical, haploid or diploid, the chromosome number in human cells, whether they contain sinale- or double-stranded chromosomes, and what the "fate" of these cells is i.e. what will they go on to do, if given the chance)?arrow_forwardIf a typical somatic cell has 12 chromosomes, how many chromatids and DNA molecules are expected in each cell of that organism?arrow_forwardHOW DO WE KNOW? how chromosomes are distributed during cell division, both in dividing somatic cells (mitosis) and in gamete- and spore-forming cells (meiosis). We found many opportunities to consider the methods and reasoning by which much of this information was acquired. How do we know that mitotic chromosomes are derivedfrom chromatin?arrow_forward
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