1. Explain how both H0- and lipid-soluble hormones are said to be genetically co
ID: 279741 • Letter: 1
Question
1. Explain how both H0- and lipid-soluble hormones are said to be genetically controlled, regulated and expressed. 2. Explain the 3 ways in which glycosylation affects the activity of peptide hormones. Calculate the MCR for the 2 patients below. Be sure to keep your units straight and express the MCR in the appropriate units. Note: 1 di 100 ml. Use minutes in your units. Which patient eliminates the thyroid hormone faster? 3. Patient B 12 ng/d 120 ml Variab Ithyroid hormone) 8 ng/d 150 ml urine amount 55 ng/di thyroid hormoner MCR 20 ng/dl Describe how binding of G-protein-coupled receptors by hormone (what kind?) results in the expression of genes into proteins. 4.Explanation / Answer
1.
Genetic regulation
Water soluble hormones cannot cross the plasma membrane thus they bind to the extracellular receptors present over the cell surface. They trigger a signalling cascade via involvement of secondary messangers such as cAMP. Receptor is generally associated with a G protein , hormone binding leads to activation of G-protein and which inturn activates adenynyl cyclase which carry out ATP to cAMP conversion . cAMP being a second messanger has targets/ activates protein kinases which phosphorylates downstream proteins present in cytoplasm.
Lipid soulble hormone are not soluble in water and can pass through the cellular membranes and binds to the target receptors present inside the cell cytoplasm. Hormone receptor complex enters nucleus will trigger a signalling cascade and regulate gene transcription and therby the target cell responds to this signal accordingly depending upon the strength of the signal, amount of hormone bound and affinity of binding.The responses can be changes in cell permeability, activating or deactivating enzymes,protein secretion or synthesis etc.
Peptide hormone recpetor is generally coupled with adenylate cyclase via G-proteins
Homone binding to receptor- activates cAMP production--which further activates protein kinases ---promotes steroid hormone biosynthesis.
2. Glycosylation affects protein activity in various ways-
1.it protects against the action of proteolytic enzymes.
2. Influences the uptake and distribution of the hormone.
3. It also affects the conformation of the hormone
4. affects the excretion and serum availability.
3. MCR (METABOLIC CLEARANCE RATE)- The rate at which the removal of hormone from blood occurs. It is expressed in terms of
MCR = RATE OF DISAPPEARANCE OF HORMONE FROM PLASMA(PER MINUTE)/HORMONE CONCENTRATION IN EACH ML PLASMA
patient A = 20 ng/dl/8 ng/dl
= 2.5ng/dl
= 2.5 ng in 100 ml
means 0.025 ng in 1 ml
Patient B = 55/12
=4.588 ng per 100 ml
means 0.0458 ng per 1 ml
Patient B has high MCR, Means it eliminates faster.
4. Explained already in PART 1
hormone binding to Extracellular receptor---- receptor Gprotein associated(GPCRs)----activated G-Protein------activation of adenynyl cyclase-----ATP to cAMP production occurs----activation of protein kinases--- further phosphorylation and activation of other protein /enzymes------ physiological effects/gene transription///changes in permeability/ secretion or synthesis of proteins.
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