Signal Transduction

Front 1

Define the concept of signal transduction (AKA cell signaling)

Back 1

Cell-surface receptors initiated the transmission of molecular signals from acell's exterior to its interior

Signals received by cells must be transmittedeffectively into the cell to ensure an appropriate response

Front 2

Different ways cells can communicate with andamong each other

Back 2

1. Contact dependent: cells are in close contact

2. Secretion of local chemical mediatorsthat are quickly absorbed, destroyed or immobilized (Paracrine cells)

3. Synaptic: releasingchemicals or neurotransmitters at specialized junctions called chemicalsynapses

4. Endocrine: Hormones are released by one set of cells andtravel through the tissue and blood stream to produce a response in another set of cells

5. Autocrine: cells produce signals that theythemselves respond to

6. Gap junction: Clusters of connexons, that allow small ion andmolecules to pass directly from the inside of one cell to the inside of anothercell

Front 3

Broadly describe the difference between how awater/plasma soluble ligand and a steroid hormone (lipid soluble) activatetheir respective signal transduction systems

Back 3

Water soluble ligand can’t readily enter themembrane because of their water structure or overall make-up of the molecule

Steroid hormones directly diffuse through thecell membrane or use transport protein and ultimately bind to a DNA regulatoryelement and stimulate gene expression which results in the synthesis of newprotein

Front 4

What is the main function of ATP and GTP in the signal transductionprocess?

Back 4

GTP source of energy or an activator of substrates inprotein synthesis and gluconeogenesis in particular withg-proteins and second-messenger mechanisms where it is converted to guanosinediphosphate (GDP) through the action of GTPases

ATP is used by kinase as the source of phosphate groups in their phosphate transfer reaction

ATP is used by adenylate cyclase as a second messenger molecule cyclic AMP which triggers the release of Ca from intracellular stores

Front 5

What is Kinases

Back 5

A kinase is an enzyme that attaches a phosphategroup to a protein from a higher energy phosphate donating molecules to a specific substrate. Kinase by phosphating other enzymes or proteins will changethe function of that enzyme. With Phosphate, kinases acts to modulate the activities of the protein in a cell

Front 6

What is Phosphates

Back 6

A phosphatase is an enzyme that removes aphosphate group from a protein. With Kinases, Phosphates acts to modulate the activities of the protein in a cell

Front 7

What is the main difference between aligand-gated and voltage-gated channel?

Back 7

Ligand-gated ion channels, which typically open when a signalmolecule binds to a receptor region of the channel protein

Voltage-gated ion channels, which respond to changes in membranepotential

Front 8

What is the unique aspect of the insulin receptor tyrosine kinase?

Back 8

Each receptor has an extracellular ligand binding domain, aswell as a transmembrane segment that contains a protein-kinase-like domain

Front 9

Howis nitric oxide (NO) generated and which second messenger system does thisactivate?

Back 9

Nitric oxide (NO) generated by L-arginine

Activationof nitric oxide in endothelial cells with a soluble form of guanylyl cylase, which stimulates GTP to form cGMP

Front 10

What is the difference between particulate andsoluble guanylyl cyclase?

Back 10

Soluble guanylyl cyclases (floats around in the cytosol and is activated by nitric oxide (NO)

Membrane or particulate guanylyl cyclases (integral proteins of the cell membrane) is activated by specific peptides (when the endogenous activator is known)