Intro to Cell Signaling

Question 1

Why is quorum sensing an attractive drug target?

Answer 1

It blocks the bacteria transition from an avirulent state to a virulent state by quorum quenching

This consist of:

inhibiting the expression of virulence genes

another ligand binding to the receptor to prevent autoinducer, extracellular signals that control quorum sensing, to bind

A molecule binding to autoinducers to prevent autoinducer to bind to receptor

A compound that destroys the autoinducer

Question 2

What are phase transition and quorum sensing?

Answer 2

Phase transition is a change in phenotype-based on coordinated changes in gene expression triggered by autoinducers.

Quorum Sensing is cell communication that influences bacteria behavior to share info. about cell density and adjust gene expression. Allow bacteria to coordinate behavior like spore formation, antibiotic production, motility, sexual conjugation.

Involves the detection, production, response to extracellular signaling molecules, autoinducers

Question 3

What are two examples of bacterial phase transition discusses in class controlled by quorum sensing?

How do bacteria use quorum sensing to regulate specialized function and the advantage of doing so?

Answer 3

In biofilm formation, there is freely suspended bacteria in the water but once the bacterial pop density reaches a high conc.. the bacteria will undergo phase transition regulated by quorum sensing that will make the bacteria stick to any surface like a boat.

In Vibro cholera, the bacteria (avirulent) come from water and float around the fluid near the intestine. Cholerae will undergo phase transition regulated by quorum sensing and will evade the mucus of the intestine and biofilm in the epithelial cells. Now that the bacteria is in a virulent phase it will lead to the secretion of salts and water, diarrhea, dehydration, and death.

Question 4

Looking at this simple pathway of the multi-step signaling pathways describe the stoichiometric and catalytic steps.

Which one of these steps can be used to amplify information being transferred?

Answer 4

Stoichiometric steps happen in a fixed stereochemistry

An example is that the receptor activates one protein which activates another protein. Ratio 1:1

Catalytic Steps is an enzyme step (not fixed stereochemistry) that amplifies the information

Ex: can activate 10 or 100 signals (amplification)

Question 5

Define the role of

Discriminators

Transducers

Amplifiers

Answer 5

Definition based on order

Discriminators- cell obtain a bunch of signaling, and cell need to discriminate their specific signal, signal binding to its specific receptors

Transducer –the information of the signal pass thru the plasma membranes (enter the cell) passes along information that signal is bound

Amplifier – the strengthen the weak signal that was transfused to create a strong impact

enhances information to increase impact

Question 6

Define the concept of homeostasis

and

True or False

Cell signaling is the obtain homeostasis.

Answer 6

Homeostatsis–living organism regulate their own internal environment often in the face of a varying external environment

and

True