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Terms in this set (20)
What are the two environments all cells must monitor?
Intracellular and extracellular
Intracellularly, the concentrations of micromolecules, macromolecules, and required _____ factors must be enough to _____ growth.
Why must cells sense their environments?
To know if the environment is hazardous, and how much food is present outside the cells
Bacterial genomes encode thousands of different proteins needed to handle many types of _____ _____.
To compete successfully with others, the microbe will not waste energy making _____ proteins.
What are the mechanisms used to control gene expression at various levels?
DNA level, transcription, post-transcription, translation, and post-translation
Microbes can program a _____ of DNA and activate/ disable a particular gene.
DNA level control is the most _____ and the least ______.
When does DNA level of control typically happen?
When genes are being shut down permanently
What are two factors that help control gene expression at the transcription level?
1. Regulatory proteins
2. Sigma factors
What are regulatory proteins and what two forms do they come in?
Proteins that help a cell sense internal changes and alter its gene expression to match.
1. Repressors (Bind to regulatory sequences in the DNA and prevent transcription of target genes)
2. Activators (Bind to regulatory sequences in the DNA and stimulate transcription of target genes)
Components of RNA polymerase holoenzyme. Bind to the gene promotor and guide RNA polymerase to start transcription.
How does the cell control sigma factors?
Either by decreasing/ increasing its activity or increasing/ decreasing its concentration
How does the cell control gene expression post-transcription?
Use of translation repressor proteins which bind to mRNA and prevent protein synthesis.
How does a cell control gene expression post-translation?
Modification of protein structure by either chemical modification (to activate or deactivate the protein) or protein cleavage (to destroy the protein)
What does a cell use to sense the external environment?
Two-component signal transduction systems
How do two-component signal transduction systems work?
External protein senses environment and relays signals to cytoplasmic protein, which then relays the info to a regulatory protein that can control gene expression
Two-component signal transduction systems are useful for sensing the environment as well as modifying the _____ and _____ of the cell without affecting transcription.
The ability of the cell to move towards environments favorable for growth and away from harsh environments.
When bacterial cells work together at a high density and secrete an extracellular molecule called an autoinducer. Autoinducers sense environment and reenter cells to bind to regulatory molecules and control gene expression.
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