#Question id: 2920
#Unit 2. Cellular Organization
Which of the following statements is INCORRECT with respect to the organization and content of the human genome?
#Question id: 361
#Unit 1. Molecules and their Interaction Relevant to Biology
Calculate the percentage of histidine that has its imidazole side chain protonated at pH 7.3. The pKa values for histidine are pK1 = 1.8, pK2 (imidazole) = 6.0, and pK3 = 9.2.
#Question id: 1911
#Unit 4. Cell Communication and Cell Signaling
Which of the following does NOT minimize allogeneic graft rejection?
#Question id: 1387
#Unit 4. Cell Communication and Cell Signaling
The ability of a population of fibroblasts to migrate along the surface of a tissue culture dish depends on adhesion between the cell surface and the extracellular matrix molecules coating the dish. The dish is coated with laminin, and the only cell-surface protein capable of binding laminin is a cell-adhesion protein called an integrin. Integrins are integral plasma-membrane proteins that function as heterodimers. Under these conditions the rate at which a fibroblast can migrate along the laminin coated culture dish is proportional to the strength of adhesion between the cell and the laminin substrate. The table below lists the rate of cell migration observed for fibroblasts genetically engineered to generate the indicated phenotypes. Microinjection into the cytoplasm of a wild. type cell of a solution of a synthetic peptide possessing the same sequence as the integrin beta subunit cytoplasmic domain would be expected to yield an average fibroblast-cell migration rat
|
Fibroblast
Phenotype |
Level of
Integrin Heterodimer at the Cell Surface (percent of wild type) |
Rate of
Cell Migration (pm/min) |
|
1. Wild type |
100 |
2 |
|
2.
Overexpression of the wild-type integrin alpha subunit |
104 |
2 |
|
3. Overexpression
of an integrin beta subunit lacking the cytoplasmic domain |
96 |
0.6 |
|
4.
Overexpression of the soluble cytoplasmic domain of an integrin beta subunit |
98 |
0.6 |
|
5. Absence of
the integrin alpha subunit |
Less than 1 |
0.05 |
#Question id: 1561
#Unit 4. Cell Communication and Cell Signaling
The cells and signaling molecules involved in the initial stages of the inflammatory response are ?