Gene expression is regulated at many levels in bacteria. Figure 14.1 in your textbook displays a summary of regulatory mechanisms used to control gene expression. An overview of gene expression in bacteria can be found at ( http://www.fda.gov/AnimalVeterinary/SafetyHealth/AntimicrobialResistance/ucm134359.htm ) . We have been discussing antibiotic resistance in bacteria; now let’s look at how this works on a molecular level. An operon is a group of genes that are regulated by one promotor. The expression of bacterial genes is controlled by the action of diffusible repressors and activators . Tetracycline is an antibiotic used to treat respiratory infections, infections of the skin, including acne, and infections of the genitourinary system. Over time however, many bacteria have become resistant to tetracycline and this antibiotic is no longer as effective as it once was. The mechanism often utilized by resistant strains is the synthesis and use of an efflux pump. While there are multiple types, in general, this pump consists of a membrane ‐ spanning protein that extrudes the antibiotic from the cell. Since efflux pumps are energetically expensive to make, they are only produced when tetracycline is present. A repressor protein , TetR, has been identified and characterized in resistant strains. The efflux ‐ pump is negatively controlled by TetR. TetR binds to the operator region when there is no tetracycline present. When tetracycline is present in the cell, it will bind to TetR and change the structure of TetR. TetR is released from the gene and the cell can produce the transmembrane protein needed to get rid of the antibiotic from inside the cell . When the antibiotic is gone, the repressor sits back on the gene. TetR gene transcription is inhibited by the repressor protein. Transcription and translation are controlled by regulatory proteins that can bind to activator binding sites in the presence of a key nutrient or other chemical in the cell. The cell is “sensing” the presence of the nutrients and the activator can then turn on genes in response. Let’s take a look at another example of operons. This video shows how the lac operon works. Combination_of_Switches_The_Lac_Operon.swf (675.139 KB) In this discussion, you will describe an operon. There are many examples listed in Chapter 14, but if you want to choose an operon not described in your book, please ask me for approval. Make sure you do not pick the same operon as your classmates; we want to expose ourselves to as many regulation proteins and bacteria as possible. In your initial discussion board post, please include the following: Describe an operon, the regulatory proteins, the cellular process and the molecules being “sensed”. Include details about the orientation of the genes and the promoter/operator sequences or activator binding site. Provide details about the repressor/activator and inducer/inhibitor proteins. Explain how the operon helps microbe survive and possib.

1. Gene expression is regulated at many levels in bacteria. Figure
14.1 in your textbook displays a summary of regulatory
mechanisms used to control gene expression. An overview of
gene expression in bacteria can be found at (
http://www.fda.gov/AnimalVeterinary/SafetyHealth/Antimicrobi
alResistance/ucm134359.htm
)
. We have been discussing antibiotic resistance in bacteria; now
let’s look at how this works on a molecular level. An
operon
is a group of genes that are regulated by one promotor. The
expression of bacterial genes is controlled by the action of
diffusible
repressors
and
activators
. Tetracycline is an antibiotic used to treat respiratory
infections, infections of the skin, including acne, and infections
of the genitourinary system. Over time however, many bacteria
have become resistant to tetracycline and this antibiotic is no
longer as effective as it once was. The mechanism often utilized
by resistant strains is the synthesis and use of an efflux pump.
While there are multiple types, in general, this pump consists of
a membrane
‐
spanning protein that extrudes the antibiotic from the cell. Since
efflux pumps are energetically expensive to make, they are only
produced when tetracycline is present. A
repressor protein
, TetR, has been identified and characterized in resistant strains.
The efflux
‐
pump is negatively controlled by TetR. TetR binds to the
operator region
when there is no tetracycline present. When tetracycline

2. is present in the cell, it will bind to TetR and change the
structure of TetR. TetR is released from the gene and the cell
can produce the transmembrane protein needed to get rid of the
antibiotic from inside the cell
. When the antibiotic is gone, the repressor sits back on the
gene. TetR gene transcription is inhibited by the repressor
protein. Transcription and translation are controlled by
regulatory proteins that can bind to activator binding sites in the
presence of a key nutrient or other chemical in the cell. The cell
is “sensing” the presence of the nutrients and the activator can
then turn on genes in response. Let’s take a look at another
example of operons. This video shows how the lac operon
works.
Combination_of_Switches_The_Lac_Operon.swf
(675.139 KB)
In this discussion, you will describe an operon. There are many
examples listed in Chapter 14, but if you want to choose an
operon not described in your book, please ask me for approval.
Make sure you do not pick the same operon as your classmates;
we want to expose ourselves to as many regulation proteins and
bacteria as possible.
In your initial discussion board post, please include the
following:
Describe an operon, the regulatory proteins, the cellular process
and the molecules being “sensed”.
Include details about the orientation of the genes and the
promoter/operator sequences or activator binding site.
Provide details about the repressor/activator and
inducer/inhibitor proteins.
Explain how the operon helps microbe survive and possibly
thrive in its environment.
Include details about conditions that trigger expression of the
gene(s).
Explain when this regulation occurs: During transcription,
translation, or posttranslat
ation.

3. Initial Discussion Post
Your initial post should be at least 250 words and must
substantively integrate the assigned readings from the module
with proper
APA
style formatting// You may use additional sources and materials
as long as they are relevant to the discussion and cited properly.
Gene expression is regulated at many levels in bacteria. Figure
14.1 in your textbook displays a summary of regulatory
mechanisms used to control gene expression. An overview of
gene expression in bacteria can be found at (
http://www.fda.gov/AnimalVeterinary/SafetyHealth/Antimicrobi
alResistance/ucm134359.htm
)
. We have been discussing antibiotic resistance in bacteria; now
let’s look at how this works on a molecular level. An
operon
is a group of genes that are regulated by one promotor. The
expression of bacterial genes is controlled by the action of
diffusible
repressors
and
activators
. Tetracycline is an antibiotic used to treat respiratory
infections, infections of the skin, including acne, and infections
of the genitourinary system. Over time however, many bacteria
have become resistant to tetracycline and this antibiotic is no
longer as effective as it once was. The mechanism often utilized
by resistant strains is the synthesis and use of an efflux pump.
While there are multiple types, in general, this pump consists of
a membrane

4. ‐
spanning protein that extrudes the antibiotic from the cell. Since
efflux pumps are energetically expensive to make, they are only
produced when tetracycline is present. A
repressor protein
, TetR, has been identified and characterized in resistant strains.
The efflux
‐
pump is negatively controlled by TetR. TetR binds to the
operator region
when there is no tetracycline present. When tetracycline
is present in the cell, it will bind to TetR and change the
structure of TetR. TetR is released from the gene and the cell
can produce the transmembrane protein needed to get rid of the
antibiotic from inside the cell
. When the antibiotic is gone, the repressor sits back on the
gene. TetR gene transcription is inhibited by the repressor
protein. Transcription and translation are controlled by
regulatory proteins that can bind to activator binding sites in the
presence of a key nutrient or other chemical in the cell. The cell
is “sensing” the presence of the nutrients and the activator can
then turn on genes in response. Let’s take a look at another
example of operons. This video shows how the lac operon
works.
Combination_of_Switches_The_Lac_Operon.swf
(675.139 KB)
In this discussion, you will describe an operon. There are many
examples listed in Chapter 14, but if you want to choose an
operon not described in your book, please ask me for approval.
Make sure you do not pick the same operon as your classmates;
we want to expose ourselves to as many regulation proteins and
bacteria as possible.
In your initial discussion board post, please include the
following:

5. Describe an operon, the regulatory proteins, the cellular process
and the molecules being “sensed”.
Include details about the orientation of the genes and the
promoter/operator sequences or activator binding site.
Provide details about the repressor/activator and
inducer/inhibitor proteins.
Explain how the operon helps microbe survive and possibly
thrive in its environment.
Include details about conditions that trigger expression of the
gene(s).
Explain when this regulation occurs: During transcription,
translation, or posttranslation
Initial Discussion Post
Your initial post should be at least 250 words and must
substantively integrate the assigned readings from the module
with proper
APA
style formatting// You may use additional sources and materials
as long as they are relevant to the discussion and cited properly.
35
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19
M3D1: Waste Not Want Not

6. Module 3
Gene expression is regulated at many levels in bacteria. Figure
14.1 in your textbook displays a summary of regulatory
mechanisms used to control gene expression. An overview of
gene expression in bacteria can be found at (
http://www.fda.gov/AnimalVeterinary/SafetyHealth/