Biology 1202B Lecture Notes - Lecture 13: Lac Operon, Lac Repressor, Operon

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20 Mar 2016

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All cells have the same complement of dna o. Yet cells of diferent type are vastly diferent. Diferences are not a result of diferent dna o o. Diferent expression of the same set of genes. Diferences are a result of regulaion of gene expression (primarily transcripion) Tend to be single celled and relaively simple o. React and adapt to changes in environment o. Manufacture the simple products needed for (brief) survival and reproducion. Depending on what is available they turn on/of various biochemical pathways. Cluster of genes and the dna sequences involved in their regulaion o. Turned on when glucose not available but lactose is. Short sequence which controls genes next to it. Lac repressor binds operator most of the ime o o o. Second level of regulaion o camp levels inversely related to glucose levels. Cap can only bind dna ater camp acivaion. When trptophan present, it acivates the repressor (therefore opposite of lac operon) o.

Related Questions

1 DNA sequences found in introns provide [A] amino acid sequence information.

[B] regulatory information.
[C] no known useful information.

[D] structure for the gene.
[E] alternative DNA splicing possibilities.

3. The TATA box is a(n)
[A] sequence close to the promoter region of many genes.
[B] square-shaped sequence.
[C] enhancer consensus sequence.
[D] activator sequence necessary for proper translation.
[E] None of the above

5. Regarding genes and gene expression, which of the following is not a difference between prokaryotes and eukaryotes
[A] Eukaryotic DNA does not contain a TATA box close to the initiation site as does prokaryotic DNA.

[B] In eukaryotes, RNA polymerase requires

'transcription factors'or initiation.

[C] Prokaryotic genes are often grouped together in

operons.

[D] In eukaryotes, the regulation of several genes at once requires common control elements in each of the genes.
[E] There is a diversity of eukaryotic polymerases that is reflected in the diversity of eukaryotic promoters.

10) In eukaryotic cells, a repressor

[A] is made of DNA.
[B] binds to the enhancer region to block transcription. [

C] is located both upstream and downstream from the promoter.
[D] binds to the operator to block RNA polymerase.

[E] binds to a silencer to reduce transcription rates.

Coordinated regulation of genes in eukaryotic cells [A] is the result of positioning the same regulatory sequence in front of each gene.
[B] results from all of those genes being under the control of one promoter.

[C] occurs because related genes all have the same

operons.
[D] occurs because enhancers cause DNA to bend.

Biology 1202B Lecture Notes - Lecture 13: Lac Operon, Lac Repressor, Operon

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