Assignment on Biology- Lac Operon Enzyme

BIOLOGY ASSIGNMENT 1
BIOLOGY ASSIGNMENT
by Student’s name
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BIOLOGY ASSIGNMENT 2
Introduction
To control the beginning and the end of transcription activities an induction process is
carried out.Lac operon, a special enzyme aids in the process of transcription. It consists of
three genes which are lacZ, lacA, and lacY. LacZ encodes enzymes which split lactose to
monosaccharide. LacY, on the other hand, encodes a membrane-embedded transporter.IPTG
acts as an inducer. It, therefore, stimulates the beginning of transcription process. Ortho-
Nitrophenyl-β-galactosidase (ONPG) was used in measuring the enzymatic activities of the
galactosidase in this experiment to indicate a yellow color when galactosidase is present.
Therefore when the intensity of the yellow color increases the enzymatic activities also
increases.
What is the biochemical function of β-galactosidase in the bacterial cell?
Β-Galactosidase helps in the initiation of metabolism of lactose in the bacterial cell
which further hydrolyses the lactose to galactose and glucose.
Explain how the expression of the lac operon (which includes the lacZ gene) is
regulated. Show a diagram of the operon, including all regulatory DNA sections,
chemicals, and proteins/enzymes, to help with your explanation.
The expression of lac operon is regulated using three genes which are lacA, lacZ, and lacY.
The genes are combined into a single mRNA which is under the control of a single promoter.
lacZ main function is to encode enzymes which splits lactose into monosaccharaides which
are fed into glycolysis. On the other hand, lacY is tasked with the encoding of a membrane-
embedded transporter which aids in bringing of lactose into the cell. Besides the three genes,
lac opera also has regulatory DNA sequences which regulate proteins thus controlling the
transcription of the operon (Witte et al., 2013 p.13).

BIOLOGY ASSIGNMENT 3
The operator in the operon is a negative regulatory site that is bounded by lac repressor
protein. In a case where the operator binds the lac repressor, RNA polymerase is not able to
bind to the promoter for transcription to start. Catabolite activator protein (CAP) acts as the
positive regulatory site. It aids in transcription by binding the RNA polymerase to the
promoter. The promoter, on the other hand, is the binding site for RNA polymerase (Runti et
al., 2013 p.5351).
The diagram below shows the operon including the regulatory DNA sections.