9 Describe the 3 major types of specification and provide examples

1
(9) Describe the 3 major types of specification
and provide examples of each type.
2
(10) The protein crystallin is found in the lens
of the eye, and is a unique marker protein for
the lens. Lens tissue is formed from ectodermal
cells located above the neural tissue that grows
out and contacts the ectoderm. A scientist has
isolated several protein fractions A-E from the
neural retina and treated ectodermal cells with
these fractions individually for 2 days.
Proteins from the treated ectodermal cells were
separated by SDS-PAGE and analyzed by Western
blot using an antibody against the crystallin
protein, shown on the gel below. What does this
blot tell you regarding these protein fractions
and lens differentiation? Why?
1 2 A B C D E MW
1 negative control 2 whole lysate (all the
proteins) A-E separate fractions of neural
retina lysate MW molecular weights of
the bands, in kilodaltons (kD)
200
125
90
60
30
3
(10) A new species of animal has been
discovered on Madagasgar, and your research
project is to study it's development. The
previous worker cloned a 13kD soluble protein,
diffusin, which has protein sequence similarity
to several morphogens in other species. What are
two major characteristics of morphogens, and how
might you experimentally show that diffusin is
really a morphogen?