Unformatted text preview: BIS 104 SS II 2011 Page 1 Name ______________________________ 1. For each of the items listed below describe i) its composition and location, and ii) its function(s). Be as
specific as possible. (8 pts)
A. NUCLEOLUS (nucleolar organizer)
i) Located within the nucleus.
Composed of clusters of multiple copies of ribosomal DNA (genes coding for rRNA) and ribosomal
subunits in various stages of assembly. ii) Nucleoli are the sites of rRNA synthesis and initial stages of ribosome assembly. B. INTEGRIN α5β3
i) One of a family of integrin trans-membrane proteins found in the plasma membranes of eukaryotic cells. ii) Functions in cell-cell adhesion and in trans-membrane signaling (e.g., can regulate VEGF expression in
tumor cells). Page 2 Name ______________________________ 2. Suppose that your research lab has a microscope equipped with an ocular lens capable of 12x magnification
and 3 objective lenses, one with 20x mag (NA = 0.8), one with 40x mag (NA = 1.0) and one with 100x mag
(NA = 1.2, oil immersion).
Abbe’ equation: d = (0.61) x ( λ ) / (n) x (sin α )
a. What is the maximal achievable magnification of this scope? Show calculation. (2 pts)
(12x ocular) X (100x objective) = 1,200x total magnification b. Using a light source with an average wavelength of 500 nm, what is the maximum resolving power of your
scope under optimal conditions? Show calculation. (4 pts)
d = (0.61) x (500 nm) / (1.2) = 250 nm 3. Based on the results of their initial set of experiments (depicted in PNAS article Figure 1) S. De, et al.
concluded that “expression of functionally competent integrin β3 confers an in vivo growth advantage.”
(referring to human prostate cancer line LNCaP).
Describe the experimental RESULTS that led to this conclusion
When injected sub-cutaneously into host SCID mice, LNCaP cells expressing active α5β3 produced
significantly larger tumors when compared to tumors produced from LNCap cells lacking active α5β3
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- Summer '08
- Nucleolus, Cell nucleus, maximal achievable magnification, B. INTEGRIN α5β3, integrin trans-membrane proteins, functionally competent integrin