BMB- 150 Genome Phage

Quiz 3 possible questions??

What is the function of an operator?

DNA sequence that is adjacent to the promoters which uses regulator proteins to bind either positively or negatively impacting, the transcription intiation by RNA polymerase from promoter

Cl protein: How does it impact lytic or lysogenic gene expression

Promotes the lysogenic cycle by binding to the operator sites and repressing Cro for lytic gene

Cro protein: how does it impact lytic or lysogenic gene expression

Promotes the lytic cycle by binding to the operator. Once bound to the operator, it prevents the expression of genes needed for lysogeny

What is superinfection? Role it plays in the Cl protein

Superinfection plays a role in lambda lysogen due to it already having Cl repressors being produced. If another phage infects the cell, then the extra Cl binds to oL and oR preventing transcription from pL and pR. Therefore, the new lambda phage cannot enter lytic cycle.

What phage and host proteins are nessesary for intergration and excision of the phage? Draw it out!

Hopefully you drew it

What method does lambda use to replicate genome in late lytic phase?

Rolling-circle replication

Function: Produces long concatemeric DNA containing multiple copies of the lambda genome joined together.

What is induction? What role does it play in Cl protein?

Induction plays a role in the Cl protein because it activates RecA causing the Cl repressor to be cleaved. Without the Cl repressor the cycle would turn the lambda lytic genes on and the phage would enter lytic cycle producing new phage and causing cell lysis.