Phytoplasmas are specialized bacteria that are obligate parasites of the phloem tissue. They are mainly

spread by insects in the families Cicadellidae (leaf hoppers),

Fulgoroidae (plant hoppers), and Psyllidae (jumping plant

lice). 

TLS Online TPP Program

#Id: 765

#Unit 3. Fundamental Processes

The closed complex is converted into an open complex of 1.3 turns of the double helix in a series of steps by first “melting” a short region of DNA. 

This Isomerization is essentially irreversible and, once complete, typically guarantees that transcription will subsequently initiate.

TLS Online TPP Program

#Id: 766

#Unit 3. Fundamental Processes

Two bases in the non-template strand of the –10 element (A11 and T7) flip out from their base-stacking interactions and instead insert into pockets within the sigma protein where they make more favorable interactions for OPC

TLS Online TPP Program

#Id: 767

#Unit 3. Fundamental Processes

Abortive transcription is when RNA Polymerase makes short transcripts, typically shorter than 10 nucleotides (nt), while still bound at the promoter.

TLS Online TPP Program

#Id: 768

#Unit 3. Fundamental Processes

In abortive transcription, an RNA chain forms without movement of the enzyme down the template by scrunching DNA

 

TLS Online TPP Program

#Id: 769

#Unit 3. Fundamental Processes

After release of the abortive product, the enzyme again begins synthesizing RNA at position +1 called as Initiation

TLS Online TPP Program

#Id: 770

#Unit 3. Fundamental Processes

Once an enzyme makes a transcript longer than 10 nucleotides, it is said to have escaped the promoter. At this point, it has formed a stable ternary complex, containing enzyme, DNA, and RNA. This is the transition to the elongation phase.