A pre-tRNA intron is excised in one step 

Finally, hydrolysis of GTP and ATP is required to join the two tRNA halves generated by cleavage on either side of the intron.

TLS Online TPP Program

#Id: 2954

#Unit 3. Fundamental Processes

By counting the number of sites to which ORC binds, we can estimate that there are about 400 origins of replication in the yeast genome. This means that the average length of a replicon is -35,000 bp.

TLS Online TPP Program

#Id: 2955

#Unit 3. Fundamental Processes

ORC was first found in S. cerevisiae (where it may be called scORC),but similar complexes have now been characterized in Schizosaccharomyces pombe (spORC), Drosophila (DmORC ), and Xenopus (XIORC).

TLS Online TPP Program

#Id: 2956

#Unit 3. Fundamental Processes

ORC is an initiation complex whose binding identifies an origin of replication.

TLS Online TPP Program

#Id: 2957

#Unit 3. Fundamental Processes

The yeast ARS elements satisfy the classic definition of an origin as a cis-acting sequence that causes DNA replication to initiate.

TLS Online TPP Program

#Id: 2958

#Unit 3. Fundamental Processes

Reconciliation between this phenomenon and the use of ORCs is suggested by the discovery that environmental effects can influence the use of origins.

TLS Online TPP Program

#Id: 2959

#Unit 3. Fundamental Processes

A nucleus injected into a Xenopus egg can replicate only once unless the nuclear membrane is permeabilized to allow subsequent replication cycles