Lac operon The operon that encodes the genes required for lactose metabolism.
The lac operon
Lactose is a sugar found in milk. If lactose is present, E. coli (the common intestinal bacterium) needs to produce the necessary enzymes to digest it. Three different enzymes are needed.
The lac operon
The capacity to respond to the presence of lactose was always there. The genes for the three induced enzymes are part of the genome of the cell. But until lactose was added to the culture medium, these genes were not expressed.
Lac operon
[edit] References
^ Gilbert, W; Müller-Hill B (Dec 1966). "Isolation of the LAC Repressor". Proc Natl Acad Sci 56 (6): 1891-1898. PMID 16591435.
Components of the lac operon of E. coli
The role of the inducer of the lac operon
Phenotype of lac Z- E. coli cells
Exchange of genetic information between bacteria
DNA transfer by an F factor
Different alleles for a bacterial genes ...
In this example (Figure 1, see Lac operon for details) the number of bacteria present in a nutrient-containing broth was measured during the course of an 8 hour cell growth experiment.
IPTG
An abbreviation for isopropyl-ß-D-thiogalactoside. A gratuitous inducer of the lac operon. That is, it can induce expression of the lac operon but it is not a substrate for the lac gene products.
inducer gene - gene encoding the repressor protein of the lac operon; when lactose binds the repressor protein, the lac operon is induced.
An enzyme involved in concentrating lactose in the cell ( coded by a gene (lac y) in the lac operon of Escherichia coli)).
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ...
 See also: Operon, DNA, Trans, Express, Expression
  
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