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Understanding Gene Regulation in Prokaryotes
Oct 11, 2024
Gene Regulation in Prokaryotes
Types of Genes
Constitutive Genes
: Always active, often called housekeeping genes.
Facilitated Genes
: Assist and help processes when needed.
Control Mechanisms in Prokaryotes
Goal: Efficient use of carbon and energy sources.
Levels of Control
:
Transcriptional Level (DNA Level)
: Proteins interact with promoters to regulate transcription.
Post-transcriptional Events
: If a gene is already transcribed, translation can be shut down.
Post-translational Modifications
: Degradation or modification of proteins to inhibit function.
Transcriptional Control
DNA Binding Proteins
:
Function by interacting with DNA in a sequence-specific manner through molecular contacts, not specific base sequences.
Important Domains:
Zinc Finger
Leucine Zipper
Helix-Turn-Helix
(emphasized for memorization)
Typically
homodimeric
: Two identical subunits; each polypeptide chain has a domain interacting with DNA sequences.
DNA Sequences and Binding
Inverted Repeat Sequences
:
Specialized sequences present in the major groove of DNA.
Described as palindromic sequences (e.g., "race car").
Inversion allows for binding of each polypeptide in the dimer with each DNA strand.
Importance of these Mechanisms
Efficient regulation of transcription is crucial for cellular conservation of resources.
Many proteins discussed are DNA binding proteins, emphasizing their role in gene regulation.
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