LABORATORY REVIEW
MITOSIS AND MEIOSIS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The DNA is different in each type of cell.
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Some cells have more or less DNA than others.
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Only specific parts of the DNA are activated.
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The DNA has genes that are expressed the same way.
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Detailed explanation-1: -We now know, however, that cell differentiation generally depends on changes in gene expression rather than on any changes in the nucleotide sequence of the cell’s genome.
Detailed explanation-2: -Cell differentiation is caused by changes in gene expression. This occurs when different signaling molecules in the environment activate or repress different transcription factors that are necessary to express certain genes in the DNA. DNA is organized inside cells into chromosomes.
Detailed explanation-3: -In order for a cell to differentiate into its specialized form and function, it need only manipulate those genes (and thus those proteins) that will be expressed, and not those that will remain silent. The primary mechanism by which genes are turned “on” or “off” is through transcription factors.
Detailed explanation-4: -Gene activity is mainly controlled by the rate of transcription of the gene, the process in which a messenger RNA is produced by RNA polymerase. Signal transduction initiates the transcription process by activating the so-called transcription factors, which are sequence-specific DNA-binding proteins.
Detailed explanation-5: -In multicellular entities, the factors that stimulate the process of cell differentiation are environmental influences, cell signalling and the level of development of entities.