Exon sequences are conserved by the negative selection of individuals in which the sequences have changed

TLS Online TPP Program

#Id: 4594

#Unit 13. Methods in Biology

Tritiated (3H) Thymidine uptake used to assess Cell Division based on radioactivity measurement by scintillation counting.

TLS Online TPP Program

#Id: 6145

#Unit 3. Fundamental Processes

Cockayne syndrome can be caused by mutations in either of two genes (CSA and CSB), both of whose products appear to be part of or bound to TFIIH, and can also be caused by specific mutations in XPB or XPD.

TLS Online TPP Program

#Id: 187

#Unit 5. Developmental Biology

In the frog (Xenopus laevis)

A gradient of the paracrine factor activin (a morphogen), causes concentration-dependent expression differences of two genes in unspecified cells.

TLS Online TPP Program

#Id: 10545

#Unit 4. Cell Communication and Cell Signaling

Binding of cytochrome c to the Apaf1 triggers formation of an apoptosome containing seven molecules each of Apaf and cytochrome c and having a sevenfold symmetry. 

TLS Online TPP Program

#Id: 8139

#Unit 2. Cellular Organization

Three major types of coated vesicles involved in protein trafficking:

1. COPII vesicles

2. COPI vesicles 

3. Clathrin-coated vesicles