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27 Cards in this Set
- Front
- Back
Why is Signal transduction important?
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Because it is how cells communicate within multicellular organisms.
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What are 3 functions that cell signalling is essential for?
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-Development
-Coordination of metabolism -Motility |
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What 3 steps have to occur for a signal to induce a cellular response?
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1. Signal needs to get across the plasma membrane
2. Signal has to be transduced through cytoplasm to the nucleus 3. Signal has to induce specific genes to be expressed |
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What gets the signal through these three steps?
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Receptors and intracellular signaling
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What are the 2 Types of Cell signalling molecules?
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1. Secreted molecules
2. Membrane-bound molecules |
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What is the general mechanism of secreted molecule signalling?
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Signalling molecules are secreted and diffuse to the target cell
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What are the 4 types of Secreted signalling?
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-Paracrine
-Autocrine -Synaptic -Endocrine |
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Which of the secreted signalling mechanisms is long range?
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Endocrine
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How does membrane-bound molecule signalling work?
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Cells with transmembrane proteins with an extracellular domain act as ligand for receptors on target cells.
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So which type of cell signalling requires direct contact between cells?
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Membrane-bound
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What are the 4 main receptor types? Which are intracellular? Which are membrane bound?
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1. Intracellular Steroid receptors
2. Membrane bound Ion channels 3. Membrane bound GPC receptors 4. Membrane bound enzyme linked receptors |
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What are the ligands for intracellular steroid receptors?
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Small hydrophobic signalling molecules
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What are 4 specific signalling molecules that bind steroid receptors?
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1. Steroid hormones
2. Thyroid hormones 3. Retinoids 4. Vitamin D |
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How do intracellular steroid receptors function after they are bound by ligand?
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As ligand-activated transcription factors.
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Where do the intracellular steroid receptors bind to their ligand?
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In the cytosol or nucleus
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How many domains do intracellular steroid receptors have, and what is each?
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Three:
1. Hormone-binding site 2. DNA-binding domain 3. Transcription-activating domain |
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What are the small hydrophobic signaling molecules (S) for Intracellular steroid receptors carreid by in the blood?
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Protein carriers - CBG
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What happens when CBG releases S?
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It diffuses through the plasma membrane
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What does S do upon entering the cytosol?
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Binds its specific receptor (GR)
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Where are the hormone receptors located?
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Either in the cytosol or nucleus
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What happens to the GR when the S binds to it?
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It induces a conformation change which activates the receptor.
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What does an activated intracellular steroid receptor do?
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Binds to hormone response elements GRE on DNA with high affinity
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Where is the GRE found?
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Near the promoter region of a target gene
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What are the 2 ways in which a GRE can regulate gene expression?
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1. Positively
2. Negatively |
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How does a GRE regulate gene expression positively?
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By stabilizing the binding of transcription factors
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How does a GRE regulate gene expression negatively?
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By repressing the binding of transcription factors.
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How many genes are generally affected by activated steroid receptors binding to their GRE?
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Only a small number
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