Gene Expression Flashcards
(29 cards)
What are magnetosomes?
Magnetic particles in some bacteria allowing orientation along Earth’s magnetic field.
What are the two types of regulatory proteins in gene expression?
Repressors and Activators.
What DNA binding motifs are used by regulatory proteins?
Helix-turn-helix, Zinc finger, and Leucine zipper.
What is the role of the arginine repressor in repression?
Binds to operator only when arginine is present (corepressor), blocking transcription.
How does lactose induce gene expression?
Lactose binds to the lactose repressor, preventing it from binding the operator.
How does maltose activate gene expression?
Maltose binds to an activator protein, allowing RNA polymerase to bind the promoter.
What is catabolite repression?
Preferential use of glucose represses genes for other carbon sources like lactose.
What is attenuation in gene regulation?
Regulation at transcription termination based on amino acid availability sensed by leader peptides.
How do small RNAs regulate gene expression?
By binding mRNA and blocking translation.
What is a riboswitch?
An mRNA region that binds a metabolite and regulates gene expression.
What is quorum sensing (QS)?
Cell-to-cell communication via signaling molecules that regulate gene expression based on cell density.
What types of molecules are used in QS?
Acyl homoserine lactones in Gram-negative and peptides in Gram-positive bacteria.
What is the function of a two-component regulatory system?
To sense environmental changes and regulate gene expression via a histidine kinase and response regulator.
What are pathogenicity islands (PAIs)?
Gene clusters acquired by horizontal gene transfer that encode virulence factors.
How does Vibrio fischeri use quorum sensing?
QS triggers luminescence when bacterial population reaches a threshold density.
What is the significance of quorum sensing in Pseudomonas aeruginosa?
QS regulates virulence and biofilm formation, contributing to antibiotic resistance.
How is bacterial chromosomal DNA packaged?
By supercoiling and binding to histone-like proteins.
What is a plasmid?
An extra-chromosomal circular DNA molecule found in bacteria.
How many genes are in the E. coli genome approximately?
Around 4500 genes.
What determines protein abundance in bacteria?
Regulation at transcription and translation levels.
What is the Shine-Dalgarno sequence?
A ribosome binding site in bacterial mRNA that helps initiate translation.
What is the start codon and what amino acid does it code for?
AUG; it codes for formylmethionine (fMet) in bacteria.
What are the three stop codons in bacterial translation?
UGA, UAA, UAG.
What is an operon?
A cluster of genes transcribed from a single promoter into a polycistronic mRNA.
