In the absence of allolactose, the repressor is present in a form that binds its site on DNA (and so keeps the lac genes switched off ). 

TLS Online TPP Program

#Id: 3632

#Unit 3. Fundamental Processes

The first two bases of an mRNA codon always form strong Watson-Crick base pairs with the corresponding bases of the tRNA anticodon and confer most of the coding specificity.

TLS Online TPP Program

#Id: 3633

#Unit 3. Fundamental Processes

The first base of the anticodon (reading in the 5'3' direction; this pairs with the third base of the codon

TLS Online TPP Program

#Id: 3634

#Unit 3. Fundamental Processes

When inosine (I) is the first (wobble) nucleotide of an anticodon, three different codons can be recognized—the maximum number for any tRNA.

TLS Online TPP Program

#Id: 3635

#Unit 3. Fundamental Processes

A minimum of 32 tRNAs are required to translate all 61 codons (31 to encode the amino acids and 1 for initiation).

TLS Online TPP Program

#Id: 3636

#Unit 3. Fundamental Processes

Rate of protein synthesis slows down when all three bases of a codon engaged in strong Watson-Crick pairing with the three bases of the anticodon.

TLS Online TPP Program

#Id: 3637

#Unit 3. Fundamental Processes

Normally there are 20 AATS exclusively specific for specific amino acid.