Hormones and cell signalling 1

How do cell signalling molecules work (very basic overview)

-Receptors expresssed by target cells.. No receptor, then no response.. SIgnalling molecules are ligands, these bind SPECIFICALLY to a site on the receptor..

Autocrine vs Paracrine vs Endocrine

Autocrine = a cell signal of that same cell which produces the signal

Paracrine = a cell that produces a signal and sends it locally

endocrine = when a target cell is a distance from the site of synthesis

What are the 4 types of cell signalling

COntact dependent

paracrine

synaptic

endocrine

How can an autocrine cell signal become amplified

If a group of identicaly signally cells have a signal.

What are the 4 consequences of cell signalling

Survive, die (apoptosis), cell growth/ division, cell differentiateion

What are the 2 types of hormone

• lipid soluble - Carrier protein through membrane + alters expression at the gene level.

• water soluble - Dissolved in the blood, + enters via RECEPTORS series of intracellular events, bind to receptors on the surface of the cell.

Examples of water soluble vs lipid soluble homones

Lipid Soluble = STEROID HORMONES… ( thyroid hormones, retinoids, vit D)

Water Soluble = Most signalling molecules + growth factors +@ water soluble hormones..

Examples of hormones produced by the adrenal glands

ANdrogen, cortisol, corticosterone, aldosterone

Examples of hormones produced by the ovaries and testes

Ovaries = estradiol

Testes = Tstosterone + Dihydrotestosterone

What happens when a hormone binds to it nuclear receptor

• Receptor, the receptor itself then becomes activated + moves to nucleaus

• active receptor binds to DNA

• regulates transcription of specific target genes..

• Every nuclear receptor complex regulates a SPECIFIC SET of genes..

How do lipid soluble hormones produce a signal inside the cell (5 marks)

1) hormone released from the transport protein and diffuses accross the cell surface membrane

2) Once inside the cell the free hormone binds to a nuclear receptor protein

3. bound receptor enters the nucleas, and the whole receptor will bind the target region of DNA

4. This will cause the transcroptional regulation of that target gene for protein synthesis and illicits a specific biological response.

therefore overall response = slower..

How do nuclear receptors work??

?Nuclear receptors vary in the N-C terminal regions, only SPECIFIC ligands will bind..

What is the function of a nuclear receptor

• Recruite additional coactivator proteins. regulate activation and repression of nearby target genes..

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What are the 5 transduction pathways of water soluble hormones

cAMP, gAMP, ion channels, tyrosine kinase, phospholipase

What is the intracellular signalling pathway

For referance only - examples of water soluble hormones and theri transduction pathway

What are the 3 components of a cell membrane receptor signally

• extracellular hormone, transmembrane domain * intracellular domane

• e.g GROWTH FACTORS BIND TO CELL MEMBRANE RECEPTORS…

Is there a difference between growth factora and cytokine

§No absolute distinction between the two terms – depends on how discovered

§Generally:

§Growth factors: polypeptides that promote cell growth and/or proliferation

§Cytokines: general term for factors associated with blood cells i.e., derived from immunology

§Paracrine and autocrine action

What do growth factors control

• division, apoptosis, + are also present in cance..

What is the half life of a hormone

the amount of time it takes for the hormone concentration to decrease by hald, amount of chemicals present which remove the signal..

transirent signals may have lasting affects, §Rate of synthesis

§Modifications of proteins e.g., + and - phosphate groups