Class notes Intro to biology

campton No transcription
a
compet
ThPadotca
-
Trp Operon encodes the 5 needed
Series of
cogmatic Raina




genes
agenes expressed
Single MENA I translated 5 proteins
-

are as a into


-



Cells need to the tip
tryptophan levels low
only express operon when are




-


Tryptophanacts like a co-repressor on the top operon


If
tryptophan
-




present in trp operon is
is the cell , not expressed




~
-




~




When tryptophan is absent transcription
-




, octors




Fal s
If
tryptophan levels low the will need to make
-


are , cell more




w/out tryptophan
-




as a
co-represer ,
the tip opeon represser
at
a e operator


expressel and
synthettrooperon
genes are can be
a
to




~
Transcription




represeorCan
tryptophan
Sometimes , prokaryotic cells need to regulate
multiple operons
Simultaneousky


oglobalgene regulation is the coordinated regulations

genes regulated globally are grouped into
regions
-




that Contain
-




regulons contain Manij different genes and operons



the same regulatory sequence

The geres of a region are controlled chosane
-


by
type of
regulatory protein
positive or

Region control
-
can be



The SOS response regular
genes
of the are spread
throughout chromosome
-
gos response the



-


Compare to anOperon


Transcriptionof Sosregulongueisblockedbycommonrepr a
-




of the reyulor

res gas that repaia




nummoneropri ma
-

Sos regulan responds t
DNA
ikea



repressor


·operat↳nu·
↑
ls




·