The sum of the number of unique genes and the number of gene families is an estimate of the number of types of genes.

The minimum size of the proteome can be estimatedfrom the number of types of genes.

TLS Online TPP Program

#Id: 6380

#Unit 2. Cellular Organization

OC are constitutive because repressor protein is unable to bind; this allows RNA polymerase to have unrestrained access to the promoter.  The Oc mutations are cis-acting/cis dominant, because they affect only the contiguous set of structural genes.

TLS Online TPP Program

#Id: 6381

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6382

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6383

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 6384

#Unit 2. Cellular Organization

The DNA-binding domain occupies residues 1–59. It contains two a-helices separated by a turn. This is a common DNA-binding motif known as the HTH (helix-turn-helix); the two a-helices fit into the major groove of DNA

TLS Online TPP Program

#Id: 6385

#Unit 2. Cellular Organization

Promoter mutations are also cis-acting. If they prevent RNA polymerase from binding at P-lac, the structural genes are never transcribed.