The thyroid hormone receptor usually forms a heterodimer with retinoid X receptor (RXR) at specific thyroid hormone response elements on the DNA

TLS Online TPP Program

#Id: 7176

#Unit 5. Developmental Biology

The “default fate” of the ectoderm is to become neural tissue

TLS Online TPP Program

#Id: 8448

#Unit 1. Molecules and their Interaction Relevant to Biology

In a typical a-helix of 12 (or n) residues, there are 8 (or n-4) hydrogen bonds.

TLS Online TPP Program

#Id: 8132

#Unit 1. Molecules and their Interaction Relevant to Biology

Lipids as pigments in plants and bird feathers.

Birds acquire the pigments that color their feathers red or yellow by eating plant materials that contain carotenoid pigments, such as canthaxanthin and zeaxanthin.

The differences in pigmentation between male and female birds are the result of differences in intestinal uptake and processing of carotenoids.

TLS Online TPP Program

#Id: 535

#Unit 2. Cellular Organization

We use the principle of parsimony in comparing the organization of orthologous genes by assuming that a common feature predates the evolutionary separation of the two species.

TLS Online TPP Program

#Id: 7200

#Unit 5. Developmental Biology

One individual, however, expresses only a small number of these molecules—up to six different class I molecules and 12 or more different class II molecules.