By "receiving chambers," I'm not sure if you mean the right atrium and left atrium or the right and left ventricles because those are also chambers within the heart that receive blood in the blood flow cycle.
<span>Discovery</span>
The operon model (Lac operon) of the regulation
of gene expression in bacteria was proposed by Jacob and Monod and hey got
noble prize in 1965 in Physiology and Medicine for this discovery.
Definition
<span> “</span><span>Operons are cluster of coregulated bacterial
genes which regulate other genes responsible for protein synthesis” </span>
Explanation
<span>Operons were first studied
in the bacterium E.coli, and they
involve the enzyme of lactose metabolism and tryptophan biosynthesis. </span>
Structure of Operon
<span> </span>Operon is generally
composed of three basic DNA components:
1. Promotor:
<span> It is a nucleotide sequence which is
recognized by RNA polymerase and initiate transcription.</span>
2. Operator:
It is a segment of DNA
that is present between the promotor and other genes to be transcribed. In presence
of repressor, RNA polymerase is physically obstructed and cannot transcribe the
genes. In the absence of repressor, operator is active and start transcription
of other proteins.
3. Structural genes:
<span>These genes are
responsible for synthesis of targeted proteins under the influence of operator<span>. </span></span>
Example of operon model:
<span> In bacteria two operon model have been
extensively studied, these are:</span>
<span> a. Lac Operon, and</span>
<span> b. Tryptophan operon</span>
Menstruation does not occur if the D) egg is fertilized.
If you are pregnant, you don't menstruate.
decomposition of what was alive then the remains are buried by sediments which results in fossilization
The theory that proposes that the universe emerged form an explosion (The Big Bang) is known as the Big Bang Theory.
Hope it helped,
BioTeacher101