Correct option is D
Chimeric embryos are generated by combining embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) that express fluorescent proteins (such as GFP or RFP). The resulting embryo will contain cells from both types of stem cells, and these cells will express the respective fluorescent proteins. However, the placenta is an extra-embryonic tissue that is derived only from the embryonic tissue (in this case, the GFP-expressing cells), and it typically does not contribute cells from the iPSC lineage (which express RFP).
Since the placenta forms from trophoblast cells that arise from the inner cell mass of the embryo (and not from iPSCs), it will not express any fluorescent protein in this case, as RFP-expressing iPSCs do not contribute to this tissue.
- Brain, Heart, and Intestine: These tissues will be composed of a mixture of cells from both the GFP-expressing ESCs and the RFP-expressing iPSCs, and thus will express both fluorescent proteins.
Therefore, the placenta will be the tissue that does not express any fluorescent protein.
Information Booster:
Chimeric Embryos: These are embryos that consist of cells from two or more different sources. In this case, the sources are GFP-expressing embryonic stem cells and RFP-expressing induced pluripotent stem cells. Both of these cell types contribute to the development of various tissues in the embryo.
Fluorescent Proteins: GFP (Green Fluorescent Protein) and RFP (Red Fluorescent Protein) are commonly used as markers to track and visualize different populations of cells in biological experiments. Cells expressing GFP will emit green fluorescence under UV light, and cells expressing RFP will emit red fluorescence.
Placenta Formation: The placenta is an extra-embryonic tissue, meaning it is not directly derived from the embryo but from the trophoblast cells, which are part of the outer layer of the blastocyst. It is responsible for nutrient exchange and does not contribute to the embryo’s tissues that would express both GFP and RFP proteins.
