BIO 3170 Lecture 10: TOPIC 10 REULATION OF GENE EXPRESSION IN BACTERIA
29 Oct 2016
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Lec 10 regulation of gene expression in bacteriophages. When phage infects a bacterium, the tail of the phage binds to the external membrane and the phage dna is injected into the bacteria: genetic material is dna - hershey chase. The two cohesive ends of lambda dna are ligated and coiled by the bacterial enzymes. Lysogenic by stimulation can turn into lytic mode. Once lytic cannot revert to lysogenic bc bacteria has died. Phage needs host to repli(cid:272)ate (cid:271)(cid:272) does(cid:374)"t ha(cid:448)e ribosomes or rna pol. Lysogenic - poor conditions, phage infects bacteria regardless of conditions and integrate host genome. Expression of phage lambda genes is none except for a repressor. Express genes in phage genome and form viral particle which leads to cell lysis and release of phages. Decision being made lyso or lytic. Lytic to lyso is not possible after certain point bc host is dead. Lytic state: new phage particles are produced and lysis of the bacteria.
