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63 Cards in this Set
- Front
- Back
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what molecule signals mating in yeast?
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peptide mating factor is realeased
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T or F: there is both sexual and asexual reproduction in yeast
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TRUE
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what are some examples of signalling molecules? Name 3.
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proteins, small peptides, steroids, fatty acid derivatives, amino acids, nucleotides, retinoids, dissolved gases such as NO and CO
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what is the concentration of signalling molecules in the body?
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less than 10^-8 M, very low concentration
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why is high receptor affinity important?
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because there is such a low concentration of signalling molecules
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how do signalling moleucles leave a signalling cell?
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exocytosis, or diffuse out, or are tightly bound to signalling cell surface
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what are the 4 types of cell-to-cell signalling?
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contact dependent, paracrine, synaptic communication, endocrine system
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what type of signalling molecule is necessary for contact-dependent cell signalling?
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need signalling molecule that binds to surface of signalling cell
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what is required for contact dependent cell signalling?
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physical contact between signalling cell and target cell, signalling molecule bound to surface of signalling cell, receptor on target cell
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is paracrine communication local or long-range?
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local
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how does paracrine signalling work?
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signalling cell secretes signalling molecule that affects cells immediately around it but not far away
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what is autocrine signalling?
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a cell secretes a molecule that acts on itself (signals itself through paracrine signalling)
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autocrine signalling is a type of ________ signalling
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autocrine signalling is a type of paracrine signalling
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what is another name for cell-to-cell signalling?
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intracellular signalling
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what are the 2 types of local cell signalling?
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contact dependent, paracrine
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what are the 2 types of long range cell signalling?
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synaptic, endocrine
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what is the advantage of synaptic communication as a long-range communication?
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it is very fast
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what type(s) of cells can neurons signal?
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other nuerons or muscle
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which type of long-range intracellular communication is faster and which is slower?
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synpatic is fast, endocrine is slow
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where are endocrine cells located?
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in the pituitary gland
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what are some differences between endocrine signalling and synaptic signallIing?
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synaptic: fast, high concentration of acetylcholine (5x10^-4 M), can target specific cells downstream of signal, lower binding affinity, reuptake removes signal quickly, more precise. Endocrine: slow, <10^-8 M hormones in bloodstream, travels throughout body, higher binding affinity, does not shut down quickly, less precise
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what is an example of a cell type that uses autocrine signalling?
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cancer cells use autocrine signalling to create a community effect and tell each other to ignore outside signals and keep divinding
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when is autocrine signalling used?
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cancer cells and also when a group of cells develops into one cell type
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what types of molecules can be exchanged through gap junctions?
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small moleucles like calcium ions and cAMP but not macromolecules
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what types of cells use gap junctions?
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groups of cells that are similar to their neighboring cells, example, heart muscle cells connected to other heart muscle cells with gap junctions
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heart cells are ________ which allows them to contract together
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electrically coupled
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gap junction is made of up 2 _______ that are joined together
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half channels
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gap junctions form a _____ duct for ions to travel through
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continuous duct
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what does gap junction allow for cells to do?
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for neighboring cells to function in a similar way in a multicellular organism
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T or F: cells can respond to only one type of signal at a time
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False; cells can respond to multiple signals simultaneously
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how does programmed cell death occur?
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the cell ignores outside signal to survive and activates its own internal cell death program
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T or F: cells always have the same receptors and proteins, they are just activated at different times to repsond to different signals at different time points
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False; cells have different receptors at different points during their cell life
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T or F: different cells will respond the same way to the same signalling molecule (signalling molecules are universaL)
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False, different cell types can respond differently to the same signalling molecule. Acetylcholine causes a decreased rate & force of contraction in the heart, and contraction of skeletel muscle cells, and secretion in the salivary gland cells
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T or F: all signalling molecules have a corresponding receptor
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False. There are steroid hormones, thyroid hormones, retinoids and vitamin D that are all small hydrophobic signal molecules that diffuse across the plasma membrane and bind to intracellular receptors
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What is are common components of a nuclear receptor?
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DNA binding domain, ligand binding domain, which is usually inhibited by an inhibitory protein
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What happens when a ligand binds to a nuclear receptor?
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the ligand causes conformational change in the receptor, which allows for the DNA to bind and recruitment of co-activator proteins needed to activate transcription
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What do co-activator proteins involved with nucelar receptors do?
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they activate transcription
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What types of sequences does the DNA binding domain recognize?
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sequences in the promoter & enhancer regions of genes
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What are the 3 types of cell surface receptors?
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ion channels/ion channel couple receptor, GPCR (G protein coupled receptor), enzyme coupled receptor
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Ion channels are used in what type of signalling?
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synaptic signalling
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what are some features of ion channel surface receptors?
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very fast, use ligands like acetylcholine, when the ligand binds the channel opens, used in synaptic signalling
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what are trimeric GTP binding proteins?
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usually inactive and bound to plasma membrane. Often coupled with g protein coupled receptors in the membrane surface
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the g coupled receptor (GPCR) is coupled with how many transmembrane domains?
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7
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how does a GPCR work?
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the ligand binds to GPCR, G proteins are activated, then other proteins/enzymes/ion channels are activated
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kinase is an example of a _____ receptor
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enzyme coupled receptor. When the receptor is activatged, it triggers its own kinase activity (it can phosphorylate things)
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what is an amplifier protein?
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amplifier proteins are involved in intracellular signaling. They are enzymes or ion channels that are part of multiple steps or a signalling cascade
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what is a transducer protein?
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transfers a signal inside the cell into a different form. Example: adenylyl cyclase
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adenylyl cyclase is a _______-
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transducer protein
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what are bifurcation proteins?
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spred the signal from one pathway to another
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name the 4 types of protein classes involved in intracellualr signaling
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amplifier proteins, transudcer proteins, bifurcation proteins, integrator proteins
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how can a signal be amplified within the cell?
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activate more and more kinases to phosphorylate things, the cell only responds to a certain strength so you have enough phosphorylation, or phosphorylate substrates which also activates proteins
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what is integration in intracellular signaling?
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a cell receives signals from multiple inputs, coincidence detection is where the cell will only follow the signal if both pathways are activated
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Name 2 types of molecular switches
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phosphorylation and GTP-binding via large trimeric GTP-binding proteins
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which is faster: scaffold protein signaling or activated receptor signalling?
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scaffold protein because everything is ready waiting on the large scaffold protein
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what are the 3 types of complexes to send signals in the cell?
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scaffold protein, activated receptor, plasma membrane
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how are scaffold proteins, activated receptors & plasma membrane complexes different?
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scaffold proteins are fast, all the componenets are ready on the scaffold protein, signal is relayed down the scaffold, activaed receptor waits until all components are there and then produces one unified signal (no relay), plasma membrane forms phosolipid complex, 2 phosphates = no complex, 3 phosphates = complex
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where is SH2 protein found?
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on adaptor proteins that can bind phosphorylated tyrosine
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what is the significance of tyrosine posphorylation?
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important signal that means that the adaptor protein can come in to form a complex
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T or F: if you moved a protein domain from its protein to a different protein, it would function the same way
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TRUE
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what is the pH domain?
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protein domain that anchors protein to phospholipids
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what are effectors?
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raise response to signals
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T or F: signalling is only important for multicellular organisms
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FALSE
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Name 3 ways to shut down a signal in a cell
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isolate the receptor by endocytosing the receptor so the ligand can't bind, degrade receptor completely, inhibit signalling at receptor level, inhibit signal somewhere in the cascade (easy to do), make another protein to inhibit the process (takes a long time)
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