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Regulation and Gene Expression

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by

Pamela Ortego

on 13 March 2014

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Transcript of Regulation and Gene Expression

Translation
Gene Regulation in Eukaryotes
- the process of protein synthesis; it decodes the
base sequence of an mRNA into the amino acid
sequence of a protein.
Transcription
- the information contained in the DNA of a specific gene is copied into messenger RNA, transfer RNA, or ribosomal RNA.
- Because prokaryotic cells do not have a nuclear membrane separating their DNA from the cytoplasm, transcription and translation are simultaneous, or coupled
Prokaryotes
2.
Elongation
: generates a growing strand of RNA
Prokaryotic genes are typically compact: therefore, many or all of the genes for a complete metabolic pathway in prokaryotes lie side by side on the chromosome.
Eukaryotes
- DNA contained in the nucleus
- nucleotide sequences
NOT
translated into protein:
INTRONS
- coding segments expressed:
EXONS.
- To convert the pre-mRNA molecule into the finished mRNA, enzymes in the nuclues
cut
the pre-mRNA apart at the
junctions
between introns and exons, and
splice together the
exons
, discarding the introns
1.)
Initiation
: Begins when tRNA and mRNA bind to ribosome
Sound Familiar?
The Central Dogma of Genetics
Gene Regulation in Prokaryotes
How are genes regulated?
Regulation of the Lactose Operon
- DNA often organized in packages called
OPERONS
:
1.)
Regulatory Gene
- codes for
the repressor protein
2.)
Promoter
- RMA polymerase
binds here
3.)
Operator
- governs access
of RNA polymerase
to the promoter
4.)
Structural Genes
- encode
the related enzymes
Consider the intestinal bacterium Escherichia coli
Eukaryotes regulate gene expression at every step of protein synthesis:
2.) Cells can control the frequency at which an individual gene is transcribed

3.) Regulation of Splicing & Processing

4.) Regulation of Transport

5.) Cells may control the stability and translation of messenger RNAs.

6.) - Proteins may require modification before they can carry out their functions.
- Cells can control the rate at
which proteins are degraded.
Quick Quiz!
Regulation and Gene Expression
- The phenotypic manifestation of a gene or genes by the processes of genetic transcription and genetic translation to produce a functional gene product, often proteins
Gene Expression
1.) What is gene expression?
2.) What is the central dogma of Genetics?

3.) Because prokaryotic cells do not have a _________ ________ separating their DNA from the cytoplasm, transcription and translation are _____________.

5.) How is the Lactose operon in prokaryotes regulated?
4.) In eukaryotic genes, what are the nucleotide sequences that are
ex
pressed in a protein and are spliced together called?

Bibliography
• "News Medical." Regulation of Gene Expression. Creative
Commons Attribution ShareAlike License, 23 Sept. 2013. Web. 23 Sept. 2013.
• Hoopes, Laura. "Gene Expression and Regulation."
Nature.com. Nature Publishing Group, 23 Sept. 2013. Web. 23 Sept. 2013.
• "Gene Expression and Regulation." Gene Expression and
Regulation - Genetics Program. David Arnostic, 23 Sept. 2013. Web. 23 Sept. 2013.
• http://www.scirus.com/srsapp/search?q=regulation+and+gene+expression&t=all&sort=0&g=s (PDF File)

By Pamela Ortego and Dominique Chow
By PAMELA ORTEGO and DOMINIQUE CHOW
by PAMELA ORTEGO and DOMINIQUE CHOW
by PAMELA ORTEGO and DOMINIQUE CHOW
3.)
Termination
: A stop codon signals the end of translation
2.)
Elongation
: Amino Acids are added one at a time to the growing protein chain

1.

Initiation:
RNA polymerase binds to the promoter of a gene.
3.
Termination
: Transcription stops when RNA polymerase reaches the sequence of DNA bases called the termination signal.

Catabolite Activating Protein (CAP)
- helps activate expression of the lac operon
& inhibit it
in the presence of glucose
- (
Catabolite

Repression
)

CAP is dependent on
Cyclic

Adenosine Monophosphate
(
cAMP
)


Adenyl Cyclase
- enzyme that catalyzes the conversion of ATP to cAMP
CAP can stimulate lac gene expression by: - interacting with RNA polymerase - responding to levels of cyclic AMP
The
Tryptophan (trp)
Operon
in E.coli
is a Repressible Gene System

- the effector molecule interacts with the repressor protein such that it can bind to the operator
In the presence of tryptophan,

the repressor binds to the regulatory region of the trp operon
represses transcription inititiation
Full transcript