VO 3 microbiology

• Bacteriostatic agents inhibit protein synthesis and can be removed, allowing growth to resume.
• Bacteriocidal agents bind firmly to their target site in the cell, are not removed by dilution, and kill the cell.
• Bacteriolytic agents kill cells by lysing them, affecting live cell count and total bacterial count.
• Penicillin is an example of a bacteriolytic agent that affects cell wall synthesis.
• The hallmarks of cellular life include coding functions, machine functions, energy production (ADP+Pi -> ATP), and metabolism for the production of macromolecule precursors.
• Allosteric feedback inhibition at the enzyme level can regulate the activity of N-Acetylglutamatsynthase (AGS) and γ-Glutamylkinase (GK).
• Glutamine synthetase is progressively adenylated when the concentration of nitrogen is high during the assimilation of ammonia.
• Glutamine synthetase (GS) can be covalently modified by stepwise adenylation, with up to twelve adenyl (AMP) groups added in a nitrogen-rich medium.
• The synthesis of the product of gene D can be prevented by control at the level of transcription.
• Feedback inhibition of enzyme activity can control the formation of the end product in a pathway.
• When the medium becomes nitrogen-depleted, the adenyl groups are removed and ADP is formed, leading to a decrease in overall GS activity.
• ppGpp and DksA promote the interaction of RNA polymerase with alternative σ-factors (σ*), such as σE.
• An innovative crystallization technique allowed researchers to determine the structure of ppGpp in complex with bacterial RNA polymerase and DksA.
• RelA catalyses the synthesis of ppGpp in response to amino acid starvation.
• Bacterial communication through quorum sensing is involved in the activation of bioluminescence in Vibrio fischeri and Euprymna scolopes.
• Signal transduction and two-component regulatory systems involve sensor kinases and response regulators.
• The 'magic spot' (MS) identified in 1969 was later identified as ppGpp and shown to influence the expression of over 500 genes in response to stress.
• LuxI synthesizes signalling molecules
• Translation can be regulated by ribosomes, initiation factors, and mRNA structure
• Riboregulation involves small regulatory RNAs that can negatively or positively regulate gene expression
• Quorum sensing is involved in adhesion, immune-defense, invasion, toxins, and biofilm formation
• Quorum sensing is a bacterial communication mechanism
• LuxR induces transcription of the lux-Operons
• Regulation of gene expression can occur at the level of transcription, translation, or protein synthesis
• Riboswitches are small molecule sensing RNAs that control both transcription and translation
• AIs bind to LuxR (Transcription factor)
• Signalling molecules (autoinducer, AI) diffuse through the membrane back into the cell
• Different σ-factors are involved in the control of mRNA synthesis
• Mechanisms used for regulation of gene expression include control at the level of translation and transcription
• Induction and repression are mechanisms of regulation in operons
• Diauxic growth is the phenomenon of bi-phasic exponential growth in the presence of two carbon sources
• Catabolite repression involves the catabolite activator protein (CAP) and the molecule cAMP
• Enzymes: metabolic catalysts
• The lac-operon encodes enzymes such as β-galactosidase and permease for lactose uptake
• Allosteric regulation is involved in the lac-operon
• Bacteria can adapt to environmental changes
• Control of mRNA synthesis can be achieved through proteins that bind to the promoter
• In anoxygenic photosynthesis, hydrogen sulfide is oxidized to produce elemental sulfur.
• Sir Francis Crick proposed the central dogma of molecular biology, which includes coding functions, machine functions, energy production, and metabolism.
• Chemoorganotrophic metabolism includes aerobic respiration, glycolysis, TCA cycle, and ATP-Synthase.