Question

Please help with questions 3,4&5

3) The protein beta-catenin is a component of several different types of cellular events that we have studied thus far this semester. Give two examples of different roles that beta catenin can play in the regulation of cellular events during development 4) You are studying the development of two novel organisms that you have discovered. After fertilization you allow the embryo develop to the four cell stage. At that point you separate the four cells and allow them to develop separately. In organism A, you observe that each of the four cells develops into a normal (although small) embryo. In organism B you observe that two of the cells form ectoderm and mesoderm tissue, while the other two form endoderm and mesoderm tissue. What does this tell out about the type of specification at work, and what underlies each type of specification? 5)A researcher is studvýing the dleavage stage in a mouse embnvo. The researcher bathes in vitro fertilized embryos in a solution containing antibodies against a portion of E-cadherin. The left figure shows the results of the control (incubating with a non-specific antibody). and the right figure shows the anti-E-cadherin treated embryos. This experiment was done during a stage called compaction in which the cells form very tight connections with one another, becoming a rounded ball instead of a collection of cells. What is happening in each of the treatments? What does the researcher hope to achieve with the antibodies in this experiment? CONTROL

Answer 1

Answer 3: Beta-catenin is a multi-functional protein. It has an important role in Wnt signalling pathway. Wnt is a glycoprotein which has roles in cell-cell interaction, cell specification and differentiation. Mutation or over-expression of beta-catenin can lead to cancer. Beta-catenin has an important role in the developmental process and also in the transcription of genes. If cell lack this protein it will lack mesoderm and cell will fail to initiate gastrulation.

Answer 4: From the experiment, we can conclude that organism A cells are independent and specified. Specified cells can grow independently if placed in an isolated environment. Hence each cell is able to grow independently of the other cells. In the organism, B cells have reached the determined stage where they are able to form what they would have formed when four cells were together. The underlying reason for each specification is the particular mRNA that has started or yet not started to form proteins for their particular cell to function. This interaction occurs with the immediate environment of the cell and all cell behaves according to the environment they are grown in.

Answer 5: In the compaction cells the strong connection between the cells is shown. A rounded ball is formed instead of individual cells. E-cadherins play important role in cell to cell tight connections in epithelial tissues and located on the surface in the area of adherence junction. In the experiment when anti-E cadherins anti-bodies are added the cells have lost their E-cadherins and are visible as individual cells. The compaction is reduced and individual cells with no adherence are visible. The researchers hope to understand the presence of E-cadherins on the overall surface of cells and how strongly they attach cells giving a compact identity.