Pharmacology | Latest 2025/ 2026 Update | 100 OUT
OF 100 |Questions and Verified Answers | GRADED A
– Portage Learning.
Mesodermal cells at the site of the limb buds respond to beads soaked in FGF8 and
grow out along the proximal-distal axis. If beads expressing FGF8 are placed under
the epithelium of the back there is no outgrowth. This experiment demonstrates
which of the following?
- Permissive induction
- Proliferation
- Competence
- Gastrulation
- Differentiation
- Competence
LEC 1.3 Slide 6
"Competence: a cell's ability to respond to an inductive signal."
Think about this: the soaked Fgf8 beads are transplanted 'under the epithelium of
the BACK ... [and] there is NO outgrowth."
Because there is no outgrowth when this is translated, this means the cells of the
back are not competent. Meaning, their signals are there/present from Fgf8,
,however, the cell's (of the back) ability to comprehend and exact the goals of the
Fgf8 signal is inadequate or incompetent.
textbook:
Cells of the responding tissue must have both a receptor protein for the inducing
factor and the ability to respond to the signal. The ability to receive and respond to
a specific inductive signal is called competence (Waddington 1940).
Researchers were examining the role of SHH on patterning the digits in the limb
bud. They predict a gradient of SHH along the rostral/caudal axis is required to
pattern the digits (left panel). Ablation of the Zone of Polarizing Activity (ZPA)
lead to the SHH concentrations in the right panel. Based on this model, which
pattern of digits (A-E) is expected.
-C
-D
-E
-A
-B
-D
LEC 1.3 Slides 14, 17-18
As can be seen in the 'real' image (not depicted here), there are 2 thresholds for red,
white, and blue for particular digits.
, The gradient depicted is a straight, horizontal line quite low on the morphogen
gradient. Because of this, red is the only color to be expressed.
Image: Researchers were examining the role of SHH on patterning the digits in the
limb bud. They predict a gradient of SHH along the rostral/caudal axis is required
to pattern the digits (left panel). Ablation of the Zone of Polarizing Activity (ZPA)
lead to the SHH concentrations in the right panel. Based on this model, which
pattern of digits (A-E) is expected.
-C
-D
-E
-A
-B
Somites are derived from which of the following embryonic tissues?
- Endoderm
- Presomitic mesoderm
- Lateral plate mesoderm
- Ectoderm
- Presomitic mesoderm
LEC 1.4 Slide 14
"Presomitic mesoderm generates somites-anlagen of the musculoskeletal system..."