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Flashcards in T5 Deck (131)
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What mediates communication between cells?

Extracellular sigbal molecules.


Outline cellular signal reception and intracellular transduction.

1. Receptor protein binds signal molecule
2. Intracellular signaling proteins moves from receptor to
3. Effector peoteins


What are the three main classes of effector proteins?

1. metabolic enzyme
2. gene regulatory protein
3. cytoskeletal protein


What is quorum sensing in bacteria?

Responding to chemical signals excreted into the intervellulsr space by other bacteria.


What different types of signal molecules are there?

"proteins, small peptides, amino acids, nucleotides, steroids, retinoids, fatty acid detivatives, and even dissolved gases"


What mechanisms does a cell have for signal presentation?

Diffusion, exocytosis and extramembraneous attachement.


Distinguish between the two receptor locayion.

Cell surface receptor and intracellular receptor.


A receptor-binding signal molecule is referred to as a...



Outline the four forms of intercellular signaling.

1. Contact-dependent
2. Paracrine
3. Synaptic
4. Endocrine


Outline contact-dependent signaling.

Bound ligand contacts bound receptor.


What type of intercellular communating has a local mediator?



Explain paracrine signaling.

Cell signaling to cells in the immediate environment.


How does paracrine signaling differ from autocrine?

In autocrine signaling signals are mediated from a certain cell type to other cells of the same type. In paracrine signaling the emitting and receiving cells are of different histological types.


How is the effect of intercellular sigbaling limited so it becomes paracrine?

Rapid receiving cell uptake, destruction by extracellular enzymes, immobilization by extracellular matrix. Heparan sulphate proteoglycan signal-binding action. Antagonists binding to signal protein or its receptor.


What defines endocrine signaling?

Release of signal molecule into the blood for transportation.


What are the similarities between synaptic and endocrine communication?

Botch have (usually) very specific target cells.


How do synaptic and endocrine signaling differ?

Whilst synaptic signaling uses the same signal substance for many different cells, endocrine signaling uses very specific signaling molecules. Synaptic response is also (usually) quick and precise, whilst endocrine is long-term, strong and affects all cells that have the target receptor. Synaptic signals are diluted much less and thus more energy efficient.


What determines hiw quickly the results are seen?

What part of the receptor cell the signal affects. Quick: altered protein function (movement, secretion, metabolism). Slow: altered gene transcription.


Give an example of gap junction-mediated cell signaling.

Noradrenaline perfusion in liver when stimulated by nerves during low blood glucose.


What are the possible different functions that different signal combinations cause in different cells?

Survival, growth and proliferation, differentiation. Lack of signals leads to apoptosis.


How does acetylcholine affect heart muscle, skeletal muscle and salivary gland cells?

Decreases rate/force of contraction, induces contraction and induces secretion.


What is a morphogen?

A molecular signal emitted from a 'signaling center', the concentration of which determines what path of differentiation nearby cells take.


What factor plays in in determining hiw quickly a intracellular signal response is detected, if the response is measured in intracellular concentration of a certain molecule?

The half-time of the molecule.


Give an example of a nuclear receptor and how it activates gene transcription.

The ligand may bind to a transcription-activating complex, allowing it to activate transcription.


Describe the path of signal transduction from acetylcholine to NO?

AC activates NO-synthase in vascular endothelial cells. NO diffuses to vascular loose muscle, activating guanylyl cyclase. cGMP is produced and induces vascular relaxation.


Give examples of ligands transducted through gap junctions.

Ca2+ and cAMP. (not proteins)


Outline the different ways of signal desensitation/adaptation.

Receptor sequestrion, receptor down-regulation, receptor inactivation, inactivation of intracellular signaling protein, production of inhibitory protein.


Name the three main cell membrane receptors.

G-protein-coupled receptors, ion-channel-coupled receptors and enzyme-coupled receptor.


How does nitroglycerine mimic te effect of acetylcholine on the vascular system?

It turns into NO, relaxing the smooth muscle.


What types of NOS (NO synthase) are there?

eNOS (endothelial), nNOS (nerve and muscle) and iNOS (inducible NOS in mitochondria).