Comparing operons: differences
While
the arabinose and lactose
operon are somewhat similar in their function, they have many important
differences. It is important to note that arabinose is much more
complex than
lactose operon. Here, you can see a summary of the differences between
the two.
Quick overview:
Positive
Control – when
regulatory protein needs to be attached in order for transcription to
occur.
Negative
Control- when
regulatory protein is needed to be removed in order for transcription
to occur.
Lactose Operon
·
The lactose operon’s function is to break
down lactose
when it is present.
·
The structural
genes of lactose operon include, LacZ, LacY, and LacA.
·
The enzymes needed for the break down of
lactose operon
is galactosidase, galactoside permease, and Thiogalactoside
transacetylase.
·
Lactose operon uses mostly negative
control. The
lactose repressor must be removed for the transcription of structural
genes to
occur.
·
The regulatory protein only regulates
structural
proteins.
·
There is only
one operator site for the lactose operon
Arabinose
Operon
- The Arabinose
Operon’s function is to break
down arabinose when it is present
- The structural genes
of arabinose operon
include: AraA, AraB, and AraD.
- The enzymes encoded
by these structural genes
and are needed in the breaking down of arabinose are Isomerase, kinase,
and epimerase
.
- Arabinose Operon uses
both positive and
negative control. The regulatory protein (AraC gene product) must be
removed from the AraO2 for the transcription to occur. Also, AraC bound
to AraI alone helps transcription of structural genes.
- The regulatory
protein regulates the structural
proteins. Also, it auto regulates itself when it binds to its own gene.
- There are two
operator sites for the arabinose
operon.
Home
Introduction
Operons
The Lactose
Operon The Arabinose Operon
Similarities
Differences
References
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all its contents have been created specifically to meet the
requirements of an exercise in the BIOL 302L course at UMBC. No
guarantees to its accuracy, expressed or implied, are
intentional. All the sources are credited in the "references"
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