BIOL 1141 Chapter Notes - Chapter 13: Trp Operon, Gene Expression, Operon

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2 Apr 2017

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Structural gene: gene that codes for the amino acid sequence of a peptide or protein. Operon: group of structural and regulating genes that function as a single unit. Regulator gene: gene that controls the expression of another gene or genes; normally located outside the operon, codes for a dna-binding protein that as a repressor. Repressor: protein molecule that binds to an operator, preventing transcription of structural genes; controls whether the operon is active or not. Promoter: a short sequence of dna where rna polymerase first attaches to begin transcription of the grouped genes, signals the start of the operon and the location where transcription begins. Operator: a short portion of dna located before the structural genes; if a repressor is attached to the operator, transcription cannot occur; if a repressor is not attached, transcription can occur; the operator controls transcription of structural genes.

Related Questions

Complete the following to describe the role that an operon plays in the synthesis of enzymes in prokaryotes.

An operon consists of an operator gene, a promoter gene, and the structural genes. When a repressor is bound to the operator, RNA polymerase cannot bind to the _________operatorpromoterstructural genes to start transcription of the _________operatorpromoterstructural genes. When a(n) _________helicaseinducerrepressorribosome is present, it binds to and inactivates the _________helicaseinducerrepressorribosomeRNA polymerase. This inactive _________helicaseinducerrepressorribosomeRNA polymerase can no longer bind to the operator. As a result, _________helicaseinducerrepressorribosomeRNA polymerase can bind to the promoter, leading to eventual transcription of the _________operatorpromoterstructural genes that encode the enzymes to be synthesized.

-operator

-promoter

-structural genes

carminechinchilla384

1.) What type of control best describes the lac operon when it is regulated by allolactose? Explain the features of this type of regulation using the lac operon as an example.

2.) What is positive gene regulation?

a) when an activator protein binds to the operator of a gene to turn expression off

b) when a repressor protein binds to the operator of a gene to turn expression off

c) when an activator protein binds to the operator of a gene to turn expression on

d) when a repressor protein binds to the operator of a gene to turn expression on

e) when a protein binds to DNA to change gene expression

3.) In the lactose operon of E. coli, what is the function of each of the following genes or sites: a) regulator, b) operator, c) promoter, d) structural gene Z and e) structural gene Y?

a) regulator gene

b) operator

c) promoter

d) structural gene Z

e) structural gene Y

4.) In a negative, repressible regulatory mechanism, transcription of the structural gene(s) occurs in

a) the presence of the co-repressor, but not in its absence.

b) the absence of the co-repressor, but not in its presence.

c) the presence of the inducer, but not in its absence.

d) the absence of the inducer but not in its presence.

e) the absence or presence of the co-repressor.

What are answers and can you explain them to me?

Fill in the blank:

promotor, induction, presence, will not, will, operon, repressor, repression, overabundance, operator, control region,

1. If the repressor is bound to the operator, then RNA polymerase______ transcribe the structural genes.

2. The ________ controls whether RNA polymerase can advance along the DNA strand or not.

3. The _______ operates differently depending on whether the operon is inducible or repressible.

4. An _________ controls the expression of functionally related genes and consists of a control region and structural genes.

5. ______ decreases expression of the structural genes. This typically occurs in response to an _____ of a substrate.

6. The _____ contains a promoter and an operator.

7. If the repressor is not bound to the operator, then RNA polymerase _____ transcribe the structural genes.

8. ______ increases expression of the structural genes. This typically occurs in response to the _______ of a substrate.

9. The ______ is the region of DNA where RNA polymerase initially binds.

BIOL 1141 Chapter Notes - Chapter 13: Trp Operon, Gene Expression, Operon

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