2.1-2.3 El Genoma Procariota

2. EL GENOMA PROCARIOTA

Genes para

mRNA

Operones

Ejemplos de operones: Operón lac

Ejemplos de operones: Operón trp

El promotor procariota

The Pribnow box (also known as the Pribnow-Schaller box) is the

sequence TATAAT of 6 bp that is an essential part of a promoter site on

DNA for transcription to occur in bacteria.

It is also commonly called the -10 sequence, because it is centered

roughly 10 base pairs upstream from the site of initiation of

transcription.

El promotor procariota

Genes para

rRNA

Genes para

tRNA

El cromosoma

procariota

Gene Expression in E. coli

Escherichia coli is probably the best characterised organism.

some numbers:

There are 4085 predicted genes in E. coli strain K-12 isolate W3110.

There are 4289 predicted genes in E. coli strain K-12 isolate MG1665.

There are about 5100 predicted genes in E. coli strain O157:H7 isolate

EDL933 (enterohemorrhagic pathogen).

Roughly 2600 genes have been found to be expressed in E. coli strain K-

12 cells, under standard laboratory growth conditions.

About 2100 spots can be seen on 2-D protein gels.

Very roughly 1000 different genes (only about 600 mRNA transcripts)

are expressed at "detectable levels" in E. coli cells grown in LB media.

Only about 350 proteins exist at concentrations of > 100 copies per cell.

(These make up 90% of the total protein in E.coli!)

El cromosoma bacteriano

Genomas bacterianos secuenciados