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GENE REGULATION
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HOWDOESACELLKNOW.
which gene to EXPRESS
&
which gene should staySILENT?
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GENE REGULATION
When a gene is EXPRESSED, it is
transcribed into mRNA.
When a gene is SILEN T, it is NOT
transcribed.
EXPRESSED GENE = TRANSCRIBED
SILENT GENE = NOT TRANSCRIBED
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EXAMPLE: Blood sugar
Pancreas Insulin
Somatic cells
Cellular
respirationATP
Kinetic energy
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QUESTIONWHYTHEPANCREASWHYNOTYOUR
LUNGS???
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GENE REGULATION
Why would a cell NOT want to
express a gene?
Wastes energy & materialsATP
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GENE REGULATION
Cells regulate what genes are
expressed based on what protein
the cell NEEDS.
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WHEREDOES GENE REGULATION
OCCUR?
Most regulation occurs
at the DNA to RNA
steptranscription!
Why?
Conserves the most
energy!
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LETSLOOKATABASICEXAMPLEOFGENEREGULATION:
E.COLIINOURGUTFEEDOFFWHATWEPUTINTOOUR
DIGESTIVESYSTEM
Proteins amino acids
Carbohydrates sugars
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PROKARYOTIC GENE REGULATION
In prokaryotes, genes are organized into operons.
What is an operon?
A group of genes that code for the same function, and
are regulated by the same promoter and operator.
One promoter/operator controls the expression of
multiple genes.
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LETSLOOKATABASICEXAMPLEOFGENEREGULATION:
E.COLIINOURGUTFEEDOFFWHATWEPUTINTOOUR
DIGESTIVESYSTEM
Proteins amino acids
Carbohydrates sugars
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PROMOTERS
What is a promoter? Specific DNA base pair sequence that provides a
binding site for RNA polymerase.
Promotes or allows transcription to occur
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LETSLOOKATABASICEXAMPLE:
E.COLIINOURGUTFEEDOFFWHATWEPUTINTO
OURDIGESTIVESYSTEM
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STARTAND STOP BASE PAIR
SEQUENCES
What do they do? Control where transcription starts and stops.
If changed (mutated), transcription is altered.
AUGUAA
UAG
UGA
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LETSLOOKATABASICEXAMPLE:
E.COLIINOURGUTFEEDOFFWHATWEPUTINTO
OURDIGESTIVESYSTEM
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OPERATORS
What is an operator?
Like an on/off switch.
Proteins bind to the operator to regulate
transcription.
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LETSLOOKATABASICEXAMPLE:
E.COLIINOURGUTFEEDOFFWHATWEPUTINTO
OURDIGESTIVESYSTEM
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REPRESSOR PROTEINS What is a repressor protein?
Binds to the operator to physically blocks
the RNA polymerase from the promoter
site.
BINDS HERE
BLOCKS THE
PROMOTER
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EUKARYOTIC GENE REGULATION Eukaryotic DNA has exons and introns.
What are exons?
The coding regions of DNA that are expressed into
proteins.
What are introns?
Non-coding regions of the DNA.
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EUKARYOTIC GENE REGULATION
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EUKARYOTIC GENE REGULATION
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CELL DIFFERENTIATION
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CELL DIFFERENTIATION
One chromosome may have several genes.
Not all the genes will be transcribed and
translated.
The genes that are transcribed and translated
determine the type of cell.
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CELL DIFFERENTIATION
So these cells all have the exactsame DNA, but each cell uses
different segments of the DNA
during transcription.
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TRANSCRIPTIONFACTORS
http://www.youtube.com/watch?v=MkUgkDLp2iE
http://www.youtube.com/watch?v=MkUgkDLp2iEhttp://www.youtube.com/watch?v=MkUgkDLp2iE7/28/2019 PP Gene Regulation
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4.46
TRP OPERON
http://www.youtube.com/watch?v=10YWgqmAEsQ
http://www.youtube.com/watch?v=10YWgqmAEsQhttp://www.youtube.com/watch?v=10YWgqmAEsQ