Week 5 S - Gene Regulation in Prokaryotes - Phage Lambda

Vocabulary flashcards based on lecture notes about gene regulation in phage lambda.

Lysis

A cycle where phage DNA is replicated, proteins are made, progeny is produced, and the cell lyses.

Lysogeny

A cycle where phage DNA is incorporated into the host chromosome and a single phage protein (cI product) is produced.

Plaques

Areas of clearing in a bacterial lawn caused by phage infection and lysis.

PL

The leftward promoter in lambda phage, driving one of the two major transcription units.

PR

The rightward promoter in lambda phage, driving one of the two major transcription units.

Immunity Region

A regulatory locus in lambda phage, containing promoters and operators.

N

An anti-terminator protein in lambda phage.

cI

Lambda repressor protein, maintains lysogeny.

Cro

Repressor protein, important for the lytic cycle.

OL

The leftward operator region in lambda phage.

OR

The rightward operator region in lambda phage.

PRM

Promoter for repressor maintenance.

PRM

The site where RNA polymerase binds and transcribes cI.

Lambda Repressor

The repressor that maintains the lysogenic state.

Lambda Repressor

The repressor not present during the lytic phase.

PRM

Overlapped by an operator and located near PR .

OR

Region consisting of three 17 bp sites.

Lambda Repressor and Cro

Can bind to the 6 operator sites in the control region.

Lambda Repressor and Cro

The six operator sites are recognized by these.

Palindrome

Each of the 6 sites are this (imperfect).

T9A12T6C12A9C11C7G9(G/C)5/5

The consensus for the half site.

Lytic Cycle

Repressor cleavage induces this.

Two helix-turn-helix domains

Required for X-repressor to bind DNA.

Mainly contacts one face of the duplex

How repressor binds to DNA.

N-terminal arms

Wrap around DNA.

Cro protein

Protein with 66 amino acids.

Helix 3

Determines DNA-binding specificity.

Repressor

Each subunit of each dimer binds one subunit of the other dimer.

RNA polymerase

Part of helix 2 interacts directly with this to promote promoter occupancy.

Cro and lambda repressor

Competition between these two.