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Advanced Higher Bio
Unit 1 Signal Transduction
Question | Answer |
---|---|
What is meant by signal transduction | converting an extracellular signal into an intracellular response |
What two hormones undergo hydrophilic signalling | insulin and ADH |
describe how insulin is transduced across a membrane (2 mark( | insulin produced by pancreas, binds to receptors on liver/muscle/fat and changes conformation - recruiting glut 4 to membrane to convert glucose to glycogen |
What transporter is recruited to the membrane in insulin signalling | Glut 4 |
What is type 1 diabetes | when then endocrine organ (pancreas) cannot produce insulin |
What is type 2 diabetes | 1. Insulin receptors less sensitive/Less numbers of ACTIVE receptors 2. Problems with recruiting Glut 4 to membrane |
WHat is the function of Glut 4 transporter | to convert glucose into stored glycogen |
What cells are target tissues of insulin signalling | fat/muscle/liver cells |
Describe how ADH is transduced across the membrane | ADH produced by pitituary gland in brain binds to ADH receptors in kidney tubule which change conformation resulting in a second messenger system that recruits AQP 2 to membrane to reabsorb water |
What channel protein reabsorbs water in ADH signalling | Aquaporin |
Is reabsorption of water active/passive transport | passive as aquaporin is a channel protein |
Where is ADH produced | pituitary gland (NOT brain) |
what is the target tissue of ADH | kidney tubules |
What is the function of ADH | to reabsorb water |
If a person was hydrated would ADH levels go up or down | down (ADH thirsty hormone) |
If a person was thirsty what would the reabsorption levels be like and what effect would this have on urine | reabsorption levels HIGH - urine small volume and concentrated |
When is the urine large volume but dilute | when a person is hydrated |
What are the two features of a person's urine when they are thirsty | small volume and concentrated |
Name two hydrophobic signalling molecules | thyroid hormone AND steroid hormones (testosterone) |
Give an example of a steroid hormone | testosterone/oestrogen |
What is the key feature of all hydrophobic signals/ligands | lipid soluble so can pass through membrane |
Where are receptor molecules in hydrophobic and hydrophilic signalling | hydrophobic (within nucleus receptors) hydrophilic (surface of cell membrane) |
After testosterone binds to its receptor in nucleus what happens next | This changes conformation of receptor resulting in it binding to gene regulatory sequences |
What happens after gene regulatory sequences have been activated | transcription occurs |
Explain why transcription only occurs after testosterone has bound | testosterone receptor is a transcription factor so only after conformational change does it bind to gene regulatory sequences to be activated |
What is the function of a thyroid hormone receptor | transcription factor inhibitor which is bound to DNA prevent transcription of protein Na/KATPase |
Where does thyroid hormone bind to its receptor | in the nucleus |
where is the thyroid hormone produced | pituitary gland (not brain) |
what is the target tissue of thyroid hormone | thyroid gland |
what does thyroid hormone do | increase metabolic rate by production of Na/K ATPase |
what happens when thyroid hormone changes conformation of its receptor | TF inhibitor breaks away from DNA allowing transcription of Na/K ATPase |
When any ligand binds to a receptor what happens next | conformational change in receptor |
What happens after a receptor has a conformational change | activate of 2nd messenger cascase e.g. phosphorylation by kinase OR activation of Gproteins/enzymes |
different types of cell may show a tissue specific response to the SAME signal - true or false | true |
A receptor can bind any ligand | false -specific ligand |