In BER,  DNA polymerase I initiates repair synthesis from the free 3’ hydroxyl at the nick, removing (with its 5’-3’ exonuclease activity) and replacing a portion of the damaged strand. 

TLS Online TPP Program

#Id: 3669

#Unit 3. Fundamental Processes

Translation starts at the 5’end of the ORF and proceeds one codon at a time to the 3’end. The first and last codons of an ORF are known as the start and stop codons.

TLS Online TPP Program

#Id: 3670

#Unit 3. Fundamental Processes

mRNAs containing multiple ORFs are known as polycistronic mRNAs, and those encoding a single ORF are known as monocistronic mRNAs.

TLS Online TPP Program

#Id: 3671

#Unit 3. Fundamental Processes

A polycistronic prokaryotic message with three ORFs. Each ribosome binding site is indicated by a purple box labeled RBS.

TLS Online TPP Program

#Id: 3672

#Unit 3. Fundamental Processes

A monocistronic eukaryotic message. The 5’cap is indicated by a “ball” at the end of the mRNA.

TLS Online TPP Program

#Id: 3673

#Unit 3. Fundamental Processes

Prokaryotic mRNAs Have a Ribosome-Binding Site That Recruits the translational Machinery For translation to occur, the ribosome must be recruited to the mRNA.

TLS Online TPP Program

#Id: 3674

#Unit 3. Fundamental Processes

Many prokaryotic ORFs contain a short sequence upstream (on the 5’side) of the start codon called the ribosome binding site (RBS). This element is also referred to as a Shine –Dalgarno sequence.