Cell Communication Flashcards
What is Quorum sensing
A process of cell–cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly.
What is the process of short range communication and examples?
Direct contact – cell contact – juxtacrine signalling (a type of cell–cell matrix signaling in multicellular organisms that requires close contact. A ligand on one surface binds to a receptor on another adjacent surface).
Gap junctions in animal cells
Plasmodesmata in plant cells
In Immunity cell recognition
What are examples of long range communication
*Soluble messengers such as;
Organic molecules (often amino acid based)
Protein based hormones
Ions (Na+, K+, Ca2+)
*Gaseous/volatile messengers such as;
NO (nitric oxide)
CO (carbon monoxide)
H2S (hydrogen sulphide)
*Neurotransmission such as;
Mediated via electrical impulses
Synapses – chemical/electrical
Neurotransmitters
3 forms of cell signaling and roles
Autocrine=self stimulation of T cells by IL-2
paracrine=clotting cascade
endocrine=insulin
Endocrine signalling
Endocrine glands secrete hormones into the blood as a stream (generally)
Pancreas – glucagon/insulin
Insulin from beta cells
Pituitary – FSH/LH
What are examples of long range signaling in plants and plant hormones with roles?
Soluble and gaseous messengers
local effects – diffusion, auto, juxta and paracrine signals.
Some longer range signals possible – xylem/phloem transport
Plant hormones:
Growth (auxins)
Abscission (abscisic acid)
Ripening (ethylene)
Protection (many)
What are ionotropic receptors
Membrane-bound receptor proteins that respond to ligand binding by opening an ion channel and allowing ions to flow into the cell, either increasing or decreasing the likelihood that an action potential will fire.
Metabotropic receptors
A metabotropic receptor, also referred to by the broader term G-protein-coupled receptor, is a type of membrane receptor that modulates cell activity. The nervous system utilizes two types of receptors: metabotropic and ionotropic receptors.
Kinase-linked receptors
Kinase-linked receptors (KLRs) are one of the main cell surface receptors. They mediate cells to communicate with each other.
Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones.
G-protein coupled receptors (GPCRs)
These are integral membrane proteins that are used by cells to convert extracellular signals into intracellular responses, including responses to hormones, neurotransmitters, as well as responses to vision, olfaction and taste signals.
Second Messengers
Often, activation of a GPCR leads to the production of small, soluble signalling molecules known as second messengers. examples include Cyclic Nucleotides – cAMP, cGMP
Lipid mediators
Ca2+-releasing messengers - inositol 1,4,5 trisphosphate (IP3)
Ca2+ signalling
Calcium can act as a third messenger and is sent as a wave.
The use of calcium ions (Ca2+) to communicate and drive intracellular processes often as a step in signal transduction. Once Ca2+ enters the cytosol of the cytoplasm it exerts allosteric regulatory effects on many enzymes and proteins.
What is allosteric regulatory effects
These effects can be positive (activating) causing an increase of the enzyme activity or negative (inhibiting) causing a decrease of the enzyme activity.
