20738126
Description
Flashcards by Marissa Alvarez, updated more than 1 year ago
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Created by Marissa Alvarez
almost 5 years ago
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| Question | Answer |
| Concepts to understand | 1) There is a constant flow of matter and information in/out cell 2) Concentration gradients 3) Cell membrane permeability 4) Membrane potential 5) Passive vs. active transport (primary vs. secondary) 6) Uniporters, Symporters, Antiporters Endocytosis, Exocytosis 7) Signal transduction. G-proteins and receptors. Tyrosine Kinase 8) Examples of pathways |
| The flow of matter & information into and out of the cell | |
| The "concentration gradient" concept As in the case of a chemical reaction: 1.) _____ diffusion in the direction of ΔG < 0 (__ the gradient) 2) Equilibrium when ΔG = __ therfore [A in] = [A out ]0 | Spontaneous along 0 |
| Living cells sustain gradients of ___ molecules and ions. Diffusion tends to ___ gradients. (Equilibrium at ΔG = 0) However, gradients are not ___ restored in cells. Lipid bilayer is a ___ barrier. ->Large ___ molecules and ions are BLOCKED from passing through. | many eliminate readily diffusion polar |
| SIMPLE DIFFUSION favors ___, ___ molecules Simple diffusion is ___ (uses no energy, moves down the concentration gradient) What molecules tend to undergo simple diffusion? | small, nonpolar passive |
| Passive/Facilitated diffusion -Large molecules, including polar, and ions can pass through ____ proteins, such as pores (____) or channels (animals) and transporters (___ ____). Transmembrane proteins that transport a SINGLE solute type is a ____ | transmembrane bacteria carrier proteins |
| Passive Facilitated Diffusion Carrier Proteins -Solute binds on one side; ____ change occurs; then lets go on other side -Often carry ONE type of molecule EX: passive ___ transporter (__) Channel Protein -Solute moves due to ___ -When ions are transported, these channels are called ___ channels. ->They are specific to __ & __ | conformational glucose (GLUT) diffusion ion size & charge |
| Some channels are always open (___ channels), while others are regulated: | Leak |
| Example of a voltage-gated channels = opening of ___ channels Neural signal ____ due to the opening of sodium channels. | Na+ propagates |
| SUMMARY So far ___ ___: no use of energy & moves along the gradient Simple diffusion: moves ___ through the cell membrane ____ diffusion: Transmembrane proteins ____ : Transmembrane protein that transports a single solute type Next Active transport: use of energy & moves ____ the gradient | Passive diffusion directly Facilitated Uniporter Against |
| Membrane Potential (___ across the membrane) Cell is like an electric battery. Cell is __ inside & __ outside. Δψ : from -40 to -70 mV ΔG = zFΔψ z = charge F = Faraday's constant Δψ < 0 and F > 0 and ΔG < 0 when z __ 0 | voltage negative 4 positive > |
| Membrane Potential is sustained by ___ /__ pumps _ N+ out & _ K+ in with a +1 charge transfer per pump cycle Cell generates 3 ΔG sources: 1) 2) 3) | sodium/potassium 3NA+ out & 2K+ in Na+ gradient K+ gradient electric potential |
| Sodium/Potassium Pump is the example of ___ Transport It is active, because ions move ___ their gradient (ΔG initial __ 0) However, A LOT of ATP energy is used (ΔG ATP __ 0) so total (ΔG total __0) | Active against > < < |
| Class Clicker Question How does membrane potential, V= -70 mV, change if a significant number of Na+ channels (transporting only sodium) synchronously open? A. will decrease, more negative B. will increase, more positive | Answer = B. will increase, more positive This is because NA+ is following its gradient via facilitated diffusion into the cell (from high to low concentration). |
| PRIMARY Active transport = when a ___ emergy source is used (__ or __) | DIRECT ATP or light |
| SECONDARY Active Transport = when the energy of ion ___ is used *Primary energy source (ATP) creates the secondary energy source (__ ___). ->This energy is used to move cargo across the membrane. Symport = two molecules move in ___ direction (move __) | gradients ion gradients same together |
| Antiport = Sodium/Calcium transporter Two molecules move in ____ directions This is active transport because the energy of the Na+ ___ is used. | opposite gradient |
| Endocytosis = ___ large molecules and particles Exocytosis = ___ | engulfing secretion |
| Transduction of extracellular signals Transduction = ___ of signal or energy from one form to another Lateral diffusion = __ (communication) Transverse diffusion = ___ | transformation fast slow |
| Signal Transduction ___ = primary messenger & binds to a receptor on the outer membrane surface |
Ligand
Image:
Ligand (binary/octet-stream)
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| ____ = on outer membrane surface ->SPECIFIC to the ligand ->Undegoes a conformational change ->SIgnal transduction ->Second messenger ->Amplification Pathways = Often ___ cell response Complex interactions | Receptor multistep |
| G protein-coupled receptors (GPCR) -Large family of protein receptors -Ligand binds to receptor -> conformational change -> signal passed Structure of GPCR = transmembrane __-___ and are couple to __ - proteins |
α - helices
G
Image:
Gpcr (binary/octet-stream)
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| G proteins (different types) are GTPases that ___ GTP GTP becomes ___ |
hydrolyze
GDP
Image:
Gtp (binary/octet-stream)
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| Heterotrimeric G-protein: α, β, γ subunits α, and γ bound to the membrane What are the signal transduction steps shown on this image? | Signal Transduction steps: 1) Signal activates receptor 2) Conformational change 3) Inactive G protein binds to receptor 4) GDP is replaced with GTP 5) GTP-α complex is activated 6) β and γ subunits leave 7) GTP- α relays signal further 8) GTP-α --> GDP-α 9) Inactive G protein is reassembled |
| Another example of a GPCR is the: Adenyl Cyclase signaling pathway Primary messengers (hormones) bind to GPCR and then G-proteins become activated and can either activate or inhibit adenyl cyclase (AC) Second messenger = cAMP (___ the signal) |
amplifies
Image:
C Amp (binary/octet-stream)
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| Kinase ___ Phosphatase ___ | phosphorylates dephosphorylates |
| The adenyl cyclase signaling pathway Phosphodiesterase = ___ cAMP (becomes AMP) *It is important to be capable of turning __ the signal. Caffeine __ the inhibitor and this results in __ signal action. | inactivates OFF inhibits |
| cAMP _ cAMP molecules must bind to the regulatory sites on the inactive complex to activate the ___ subunits ->This activates protein __ __ |
4
catalytic
kinase A
Image:
C Ampp (binary/octet-stream)
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| Tyrosine Kinase Pathway -Ligand binding causes ___ -Each kinase ___ its partner (auto___) -Phosphorylated dimer becomes ___ | dimerization phosphorylates autophosphorylation active |
| Insulin receptor is an example of a tyrosine kinase receptor -Tyrosine kinase domains catalyze phosphorylation of proteins called insulin receptor substrate (IRS) to further produce secondary messengers (PIP3). |
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