Frequency-dependent selection,

1.    Positive frequency

2.    Negative frequency

TLS Online TPP Program

#Id: 7084

#Unit 3. Fundamental Processes

Mutations that remove the 2’-OH of the A residue at the 30 end of the P-site tRNA result in a 106-fold reduction in catalysis rates. This “substrate-assisted catalysis”

2’-OH of the P-site tRNA may act as part of a “proton shuttle”

TLS Online TPP Program

#Id: 7085

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 7086

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 7087

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 7088

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 7089

#Unit 3. Fundamental Processes

IF1 prevents tRNAs from binding to the portion of the small subunit that will become part of the A-site.

†IF2 is a GTPase that interacts with three key components of the initiation machinery: the small subunit, IF1, and the charged initiator tRNA (fMet-tRNAi f-Met). By interacting with these components, IF2 facilitates the association of fMet-tRNAi f-Met with the small subunit and prevents other charged tRNAs from associating with the small subunit.

† IF3 binds to the small subunit and blocks it from reassociating with a large subunit. Because initiation requires a free small subunit, the binding of IF3 is critical for a new cycle of translation.