Control of Gene Expression

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Chapter 10

• Control of Gene Expression

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Gene Expression

• Not all of the genes in a cell are used
• Some lie dormant, while others are actively used

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Pipeline of Expression
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The lac Operon
No Lactose, no need to waste energy trying to use
it
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The lac Operon
Lactose present, time to make enzymes to use it!
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The Full Genome
Cells contain all of the genes necessary to make
a new individual
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Limited Expression of Genes
While cells contain the entire genome, not all of
the genes are expressed in every cell
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DNA Packing
DNA is tightly packed when in the
nucleus Multiple processes must take place to
prepare for protein synthesis
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Transcription Regulation
Lots of pieces are needed to get transcription
started Any alteration and the protein is not
synthesized
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RNA Splicing
RNA can be modified after its creation to make
various proteins at different times in cell
development
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Cytoplasmic Regulation
In the cytoplasm, RNA can be broken down,
Translation can be stopped, and proteins can be
modified or broken down All depend on signals
from inside and outside of the cell.
Enzymes/Proteins
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Fruit Fly Development
All based on cell signaling from proteins made by
neighbors
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Oncogene Formation
Mutation in the gene, multiple copies of the
gene, move to a new locus
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Tumor-Suppressor Genes
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Cancers and Carcino-gens
We know of many factors that can increase the
rate of cancer, notably cigarettes
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Summary

• Gene Regulation the lac operon
• Patterns of Expression and the Genome
• Transcriptional Regulation
• Cytoplasmic Regulation
• Embryonic Development
• Cancer mechanisms, causes