Please help with a,b an c (developmental biology) NAME Worksheet Developmental B
ID: 151031 • Letter: P
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Please help with a,b an c (developmental biology)
NAME Worksheet Developmental Biology Laboratory Principles of Cellular Development II: Cell Aggregation t. Cells from the sponge Microciona were dissociated in calcium and magnesium free seawater, gyrated for two hours in cold, and the cells separated from the supernatant (which contains the aggregation factor). The cells were placed in seawater in test tubes (a) at 4°C, (b) room temperature, and (c) at 4°C in the presence of aggregation factor. In addition, four different sugars were added to the test tubes. After two hours, the tubes were scored for number and size of cell aggregates. The results are shown below: (+) indicates large number of aggregates; () indicates no clumps Clumps in Absence of Aggregation Factor Clumps in Presence of Aggregation Factor at 4°C ot 22 C at 4°c Sugar Added None (ASW onl Sugar A Note: ASW Artificial Seawater; 22°C Room Temperature Answer the following questions from the data in the above table: a. Why was aggregation observed at 22 C but not at 4°C in the absence of aggregation factor? The third column represents a competition experiment. Describe what competition is taking place in terms of (1) the aggregation factor, (2) the cell surface receptors, and (3) the saccharide ligand. b. What does the result from the third column tell you about the chemical composition of the aggregation factor and the cell surface receptors? c.Explanation / Answer
a)The aggregation is observed at 22 c and not 4 c because at 22 C the enzyme works at room temperature while in cold ast 4 C it does not reproduce and it stops working and is an inhibition mode
b)The competition taking place is that aggregation factor is high for suga a,b,c and low for D. The cell surface recptors act for sugar a,b,c while they stop working for the sigar d completely
c)The chemical composition of aggregation is that it comprises of positive ions while the cell surface receptors are activated for SUGAR A,,B,C while they stop for sugar D
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