Term
| Why is cell signalling important? |
|
Definition
| So cells can respond to other cells and their environment |
|
|
Term
| How much of the eukaryotic genome codes for factors involved in cell signalling? |
|
Definition
|
|
Term
| What is the shortest and quickest way of cell signalling? |
|
Definition
|
|
Term
| What types of molecules can pass through gap junctions? |
|
Definition
| Na+, Ca2+, K+, Sugars, ATP and cAMP |
|
|
Term
| What types of molecules can't pass through gap junctions? |
|
Definition
| Proteins, nucleic acids and polysaccharides |
|
|
Term
| What is the second shortest and quickest way of cell signalling? |
|
Definition
| Contact dependent and paracrine signalling |
|
|
Term
| How does contact dependent signalling work? |
|
Definition
| One cell receives a signal which it then amplifies to produce the same effect on the surrounding cells |
|
|
Term
| How do gap junctions work? |
|
Definition
| Direct cell to cell pores can be used to pass molecules in order to create a direct effect in the conjoined cell |
|
|
Term
| What is the second longest and slowest way of cell signalling? |
|
Definition
|
|
Term
| What is the simple signalling pathway? |
|
Definition
| Signal -> Reception -> Response |
|
|
Term
| What is the complex signalling pathway? |
|
Definition
| Signal -> Reception -> Transduction -> Amplification -> Response |
|
|
Term
| How can the activity of proteins in a signalling pathway be altered? |
|
Definition
| By changing the level or activity of that protein |
|
|
Term
| How does a conformational change affect the activity of a protein? |
|
Definition
| By a molecule binding to the protein that either activates or deactivates it |
|
|
Term
| How does covalant modification affect the activity of a protein? |
|
Definition
| By a phosphate group binding to the protein that either activates or deactivates it |
|
|
Term
| What are the two types of position of a receptor? |
|
Definition
| Intracellular and Cell-surface |
|
|
Term
| Name two signal molecules that use intracellular receptors? |
|
Definition
| NO gas and Steroid hormones |
|
|
Term
| Name two signal molecules that use cell-surface receptors? |
|
Definition
| Cytokines and Neurotransmitters |
|
|
Term
| Outline the mechanism involved in nuclear hormone receptors? |
|
Definition
| Signal molecule binds to the LBD which removes the inhibitor molecule. The receptor the undergoes a conformational change. The DBD then binds directly to a gene on DNA in order to replicate it. |
|
|
Term
| What are the three domains that make up the nuclear hormone receptor? |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| What happens if a cell has no receptor for a particular signal molecule? |
|
Definition
| No response can ever happen in the cell |
|
|
Term
| What happens if no androgen is administered to the fetus? |
|
Definition
| The fetus follows a female growth pattern |
|
|
Term
| What causes Androgen Sensitivity Syndrome? |
|
Definition
| Lack of receptors in the body that detect testosterone and so male embryo follows female development |
|
|
Term
| What happens to the phenotype of individuals with Androgen Sensitivity Syndrome? |
|
Definition
| They have the genus of XY but the phenotype of a woman. They develop breasts and female genitalia. |
|
|
Term
| Outline the mechanism involved in nitric oxide receptors? |
|
Definition
| Acetylcholine binds to NO synthase in the epithelial tissue. The NO synthase then produces NO. The NO then binds to guanylyl cylase in the smooth muscle cells. Guanylyl cyclase then converts GTP into cGMP. The production of cGMP rapidly relaxes the smooth muscle |
|
|
Term
| Which is the secondary messenger in the mechanism of nitric oxide receptors? |
|
Definition
|
|
Term
| What are the three families of cell-surface receptors? |
|
Definition
| Ion-linked channel receptors, G-protein linked receptors and Enzyme-linked receptors |
|
|
Term
| How do ion-linked channel receptors work? |
|
Definition
| An ion/ligand binds to the receptor which opens the channel protein allowing molecules to leave or enter the cell |
|
|
Term
| What is the alternative name for ion-linked channel proteins? |
|
Definition
| Ligand gated channel proteins |
|
|
Term
| Where are ion-linked channel proteins most commonly found? |
|
Definition
| On the post-synaptic membrane of the post synaptic neuron |
|
|
Term
| Outline the mechanism of nicotinic acetylcholine receptors in causing a muscle contraction? |
|
Definition
| Acetylcholine binds to the receptor on the nicotinic ectylcholine channel protein. This causes an influx of Na+ ions which depolarises the post-synaptic membrane. This causes Ca2+ ions to be released from the sarcoplasmic reticulum. The Ca2+ ions then bind to the sarcomere inducing a muscle contraction |
|
|
Term
| What is the signal molecule for nicotinic acetylcholine channel proteins? |
|
Definition
|
|
Term
| What is the signal molecule that binds to NO synthase? |
|
Definition
|
|
Term
| Name a genetic disorder that occurs as a result of faulty nicotinic acetylcholine receptors? |
|
Definition
|
|
Term
| What are the symptons of Myasynthenia Gravis? |
|
Definition
| Drooping eyelids and difficulty in walking and speaking |
|
|
Term
| What causes Myasynthenia Gravis? |
|
Definition
| An autoimmune response that causes antibodies to block the nicotinic acetylcholine receptors |
|
|
Term
| What is the alternative name for a G-Protein linked receptor? |
|
Definition
|
|
Term
| How many domains of the membrane does a G-Protein linked receptor span? |
|
Definition
|
|
Term
| What biological processes does a G-Protein linked receptor coordinate? |
|
Definition
| Scent, Neurotransmitters, Vision, Immune and ANS |
|
|
Term
| On average how many G-Protein linked receptors are in the human body? |
|
Definition
|
|
Term
| What are G-Protein linked receptors associated with? |
|
Definition
|
|
Term
| What are the two types of G-Protein? |
|
Definition
|
|
Term
| What are Enzyme-linked receptors associated with? |
|
Definition
|
|
Term
| G-Proteins are know as what? |
|
Definition
|
|
Term
|
Definition
| A molecule that converts a signal in one form into a signal in a different form |
|
|
Term
| What are the subunits of a trimeric G-Protein? |
|
Definition
|
|
Term
| What is the role of the alpha-subunit in a trimeric G-Protein? |
|
Definition
|
|
Term
| What is bound to the alpha-subunit at rest? |
|
Definition
|
|
Term
| What is bound to the alpha-subunit when active? |
|
Definition
|
|
Term
| What occurs to switch off the alpha subunit? |
|
Definition
| The hydrolysis of the bound GTP to GDP |
|
|
Term
| How does the alpha-subunit of trimeric G-Proteins transduce signals? |
|
Definition
| By activating other membrane-bound proteins |
|
|
Term
| What are the two membrane-bound proteins that the alpha-subunit of trimeric G-Proteins activates? |
|
Definition
| Adenylyl Cyclase and Phospholipase C |
|
|
Term
| What enzyme converts GTP to GDP to deactivate the alpha-subuit of trimeric G-Proteins? |
|
Definition
|
|
Term
| What does the enzyme GTPase do? |
|
Definition
|
|
Term
| What is the secondary messenger of Adenylyl Cyclase? |
|
Definition
|
|
Term
| What does Adenylyl Cycyalse do? |
|
Definition
|
|
Term
| What are the secondary messengers of Phospholipase C? |
|
Definition
|
|
Term
|
Definition
| Inositol,1-4-5 triphosphate |
|
|
Term
|
Definition
|
|
Term
| How does cAMP act as a secondary messenger? |
|
Definition
| It binds to a cAMP dependant protein kinase which activates catalytic subunits |
|
|
Term
|
Definition
| cAMP Dependant Protein Kinases |
|
|
Term
| What does the enzyme protein kinase do? |
|
Definition
| Converts ATP to ADP and phosphorylates a substrate |
|
|
Term
| What does the enzyme phosphotase do? |
|
Definition
| Removes a phosphate group from a substrate |
|
|
Term
| What are the three roles of GTP and ATP in a cell? |
|
Definition
| Nuceleic acids, energy stores and secondary messengers |
|
|
Term
| What is the alternative name for adrenaline? |
|
Definition
|
|
Term
| Outline the mechanism for a cells response to epinephrine? |
|
Definition
1)Epinephrine binds to G-Protein linked receptor
2)Alpha-subunit of the trimeric G-Protein binds GTP and is activated
3)Activated alpha-subunit activates adenylyl cylase
4)GTP converted to GDP and alpha subunit becomes deactivated
5)Adenylyl cyclase converts ATP into cAMP
6) cAMP activates protein kinase A
7)Protein kinase A activates phosphorylase kinase and deactivates glycogen synthease A by phosphorylation
8)Phosphorylase kinase activates phosphorylase B by phosphorylation
9) Phosphorylase B phosphorylates glycogen to produce glucose |
|
|
Term
| Which enzyme phosphorylates Phosphorylase B? |
|
Definition
|
|
Term
| Which enzyme phosphorylates glucose? |
|
Definition
|
|
Term
| Which enzyme phosphorylates phosphorylase kinase? |
|
Definition
|
|
Term
| Which enzyme pshosphorylates glycogen synthase? |
|
Definition
|
|
Term
| What does Phospholipase C do? |
|
Definition
| Breaks down PIP2 into IP3 and DAG |
|
|
Term
| What does PIP2 stand for? |
|
Definition
| Phosphoinositol 4,5-bisphospahte |
|
|
Term
|
Definition
| Binds to the endoplasmic reticulum to relase Ca2+ ions |
|
|
Term
|
Definition
| Binds to protein kinase C to activate it when Ca2+ binds |
|
|
Term
| Why is Ca2+ used a secondary messenger? |
|
Definition
| It is present in low levels normally so can be detected easily and binds strongly |
|
|
Term
|
Definition
| When four Ca2+ ions bind to it a conformational change occurs and the molecule can then be used to activate other molecules |
|
|
Term
| What does protein kinase C do? |
|
Definition
| Activates a phosphorylation cascade |
|
|
Term
| Outline the mechanism that involves Phospholipase C? |
|
Definition
1)Signal molecule binds to G-Protein linked receptor
2)Alpha-subunit binds GTP and activates Phospholipase C
3) Alpha-subunit hydrolyses GTP to GDP and becomes deactivated
4) Phospholipase C breaks down PIP2 into IP3 and DAG
5) IP3 binds to endoplasmic reticulum to release CA2+
6) Ca2+ and DAG bind to protein kinase C
7)Protein kinase C activates a phosphorylation cascade |
|
|
Term
| How many domains does an enzyme-liked receptor have? |
|
Definition
|
|
Term
| What are the two types of enzyme-linked receptor sgnal molecules |
|
Definition
|
|
Term
| Waht is the most common type of enzyme-linked receptor? |
|
Definition
| Receptor Tyrosine Kinases |
|
|
Term
|
Definition
| Receptor Tyrosine Kinases |
|
|
Term
| The insulin receptor is a type of? |
|
Definition
|
|
Term
| Cancer is most commonly associated with what kind of receptor? |
|
Definition
| Receptor Tyrosine Kinases |
|
|
Term
| What happens on the cytoplasmic domain of receptor tyrosine kinases? |
|
Definition
| Cross phosphorylation that autophosphorylates the enzyme stack |
|
|
Term
| Insulin receptors are what? |
|
Definition
|
|
Term
| What happens after the receptor tyrosine kinase becomes phosphorylated? |
|
Definition
| Other enzymes and proteins dock and become phosphorylated |
|
|
Term
| What is Ras an example of? |
|
Definition
|
|
Term
| What are the three differences between trimeric and monomeric G-Proteins? |
|
Definition
1)Trimeric G-Proteins are linked directly to the receptor whilst monomeric are not
2)Trimeric G-Proteins Receptors activate GDP release. Monomeric G-Proteins have a GEF that releases GDP
3)Trimeric G-Proteins hydrolyse GTP to GDP on its own, monomeric G-Proteins require GAP |
|
|
Term
|
Definition
| Guanine Nucleotide Exchange Factor |
|
|
Term
|
Definition
| GTPase Activating Protein |
|
|
Term
| Outline the mechanism that activates Ras? |
|
Definition
1) Signal molecule binds to enzyme-linked receptor
2)Cytoplasmic domain becomes autophosphorylated
3)Grb-2 docks to the phosphorylated column and becomes phosphorylated
4)Grb-2 phopphorylated GEF
5)GEf converts GDP to GTP and activated Ras |
|
|
Term
|
Definition
| Activates a MAP kinase pathway |
|
|
Term
| Outline the MAP kinase pathway? |
|
Definition
1)Ras activates Raf kinase
2)Raf kinase converts ATP to ADP and phosphorylates Mek kinase
3)Mek kinase converts ATP to ADP and phosphorylates Erk Kinase
4)Erk kinase then converts ATP to ADP and phosphorylates protein X and Y and gene regulatory protein A and B |
|
|
Term
| What does proteins X and Y do in the MAP kinase pathway? |
|
Definition
|
|
Term
| What do gene regulatory proteins do in the MAP kinase pathway? |
|
Definition
|
|
Term
| Ras mutations are present in what percentage of human cancers? |
|
Definition
|
|
Term
| What is the most common type of Ras mutation? |
|
Definition
| Unable to hydrolyse GTP so MAP kinase pathway is permanently switched on |
|
|
Term
| How can cells respond differently to the same signal molecules? |
|
Definition
| By having different receptors and different phosphorylation cascades |
|
|
Term
| Name two receptors that respond to acetylcholine differently? |
|
Definition
| Nicotinic acetylcholine channel proteins and Muscarinic Ach G-Protein linked receptors |
|
|
Term
| Outline the mechanism involved in muscarinic Ach G-Protein receptors? |
|
Definition
1)Acetylcholine binds to the muscarinic Ach G-Protein receptor
2)Beta/Gamma-subunit of trimeric G-Protein binds GTP
3)Beta/Gamma subunit binds to K+ ion channel causing an eflux of K+ ions
4)The eflux of K+ ions reduces heart rate |
|
|
Term
| What is the signal molecule of muscarinic Ach G-Protein receptors? |
|
Definition
|
|
Term
| Outline the mechanism involved in pancreatic acinar G-protein linked receptors? |
|
Definition
1)Acetylcholine binds to pancreatic acinar G-Protein linked receptor
2)Alpha-subunit binds GTP and activates Phospholipase C
3)GTP is hydrolysed to GDp and the alpha subunit becomes deactivated
4)Phospholipase C hydrolyses PIP2 to DAG and IP3
5) IP3 binds to endoplasmic reticulum to release Ca2+
6)Ca2+ binds to calmodium to activate a phosphorylation cascade
7)Phosphorylation cascade results in secretory vesicles containg alpha-amylase to be secreted |
|
|
Term
| What is the signal molecule for pancreatic acinar G-Protein linked receptors? |
|
Definition
|
|
Term
| Outline the mechanism involved in NO secretion of epithelial cells? |
|
Definition
1)Acetylcholine binds to G-Protein linked receptor
2)Alpha-subunit binds GTP and activates Phospholipase C
3)GTP is hydrolysed to GDp and the alpha subunit becomes deactivated
4)Phospholipase C hydrolyses PIP2 to DAG and IP3
5) IP3 binds to endoplasmic reticulum to release Ca2+
6)Ca2+ binds to calmodium to NO synthase to produce NO
7) NO is then secreted and relaxes the smooth muscle |
|
|
Term
| What is the signal molecule for the G-Protein linked receptor of epithelial tissue? |
|
Definition
|
|
Term
| What are the four general responses of cells to cell signaling? |
|
Definition
| Survival, division, differentiation and death |
|
|
Term
|
Definition
| Two receptors are activated to either double phosphorylate one molecule or phosphorylate two molecules that join to form one |
|
|
Term
|
Definition
| Overlap between two or more signalling pathways |
|
|
Term
|
Definition
|
|
Term
| What is the advantage of having the same signal molecule in many pathways? |
|
Definition
| Allows cross talk and fine tuning |
|
|
Term
| What is the disadvantage of having the same signal molecule in many pathways? |
|
Definition
| Possibility of incorrect response |
|
|
Term
| What are the two types of signalling complexes? |
|
Definition
|
|
Term
| What is a stable signalling complex? |
|
Definition
| One permanent scaffold that becomes phosphorylated when stimulated |
|
|
Term
| What is a transient signalling complex? |
|
Definition
| And assebling scaffold that becomes phosphorylated but is degraded afterwards |
|
|
Term
| What could occur if signalling pathways are not switched off? |
|
Definition
|
|
Term
| Drugs work by enhancing or inhibiting the switching on or off process? |
|
Definition
|
|
Term
| How can signalling pathways be degraded? |
|
Definition
| Remove receptor, signal molecules, associated proteins or secondary messengers |
|
|
Term
| What are the three ways that a signal can be removed? |
|
Definition
| Degradation, recycling or sequestration |
|
|
Term
| How is a signal molecule removed by degradation? |
|
Definition
|
|
Term
| How is a signal molecule removed by recycling? |
|
Definition
| Reabsorbtion into the signal releasing cell |
|
|
Term
| How is a signal molecule removed by sequestration? |
|
Definition
| Removal of signal and receptor by an enzyme |
|
|
Term
| How long does it take on average for acetylcholine to be removed? |
|
Definition
|
|
Term
| How long does it take on average for NO to be removed? |
|
Definition
|
|
Term
| How long does it take on average for water soluble hormones to be removed? |
|
Definition
|
|
Term
| How long does it take on average for steroid hormones to be removed? |
|
Definition
|
|
Term
| What are the two ways that a receptor can be removed? |
|
Definition
| Down-regulation and sequastration |
|
|
Term
| How is a receptor removed by down-regulation? |
|
Definition
| Receptor taken in by endocytosis and then hydrolysed and destoryed by fusion with a lysosome |
|
|
Term
| How is a receptor removed by sequestration? |
|
Definition
| Receptor is taken in by endocytosis, signal molecule is removed and then released back by exocytosis onto the membrane |
|
|
Term
| How does the Cholera toxin disrupt the cell signalling pathway? |
|
Definition
1)Binds to alpha-subunit and prevents hydrolysis of GTP so it remains active
2)Results in constant stimulation of adenylyl cylcase
3)Cl- and H20 channels are permanently left open which results in diarrhea |
|
|
Term
| What is allosteric activation? |
|
Definition
| Activation as a cause of association or dissasociation with another molecule |
|
|
Term
|
Definition
| Hydrolysis by phosphodiesterases |
|
|
Term
|
Definition
| It inhibits the cGMP phosphodiesterase so muscles are constantly relaxed maintaining an erection |
|
|
Term
|
Definition
| It inhibits the recycling of signal molecules |
|
|
