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CellBio
| Question | Answer |
|---|---|
| What does unsaturated mean? | A double bond is present in a phospholipid and there is a decrease in the number of hydrogens that can be bound to the carbon atoms. |
| What are the 3 factors that have a profound effect on the fluidity of the phospholipid bilayer? | 1) The length of the fatty acyl tails. Shorter tails = more fluid. 2) The presence of double bonds (unsaturation) more double bonds = more fluid. 3) The presence of cholesterol. Cholesterol tends to stabilize membranes vs the effects of temperature. |
| What are the two experiments used to prove fluidity? | The mouse and human cell mixed together, FRAP experiment. |
| What was the procedure for the human/mouse cell experiment. | A mouse and human cell was fused. the temperature was lowered and a flourescently labeled antibody that recognized the mouse H2 protein was added. (control) Incubate a cell then cool and add the same anit.. Due to the lateral movement h2 is everywhere. |
| What was the procedure for the FRAP experiement? | Flourescent molecule labeles cell surface proteins, expose cell o laser beam which bleaches a small region on the cell surface, incubate and due to lateral movement, the bleach and unbleach molecules mix with eachother. |
| Glycosylation | The process of covalently attaching a carbohydrate to a protein or lipid. |
| Glycolipd | Carbohydrate attached to a lipid |
| Glycoprotein | Protein attached to a carbohydrate |
| mannose-6-phosphate | proteins that are destined for the lysosome are glycosylated and have this sugar that is recognized by other proteins in the cell. |
| glycocalyx | cell coat, carbohydrate-rich zone on the cell surface that shields the cell from mechanical and physical damage. |
| transmission electron microscopy | sample is thin sectioned and stained with heavy metal dye. |
| Freeze fracture electron microscopy | sample is frozen in liquid nitrogen, split and fractured. coated with metal and viewed under the electron microscope. |
| P-face | Leaflet in a FFEM sample. protoplasmic face that was next to the cytosol |
| E-face | Leaflet in a FFEM sample. extracellular face |
| transport proteins | allow membranes to be selectively permeable by providing a passage way for the movement of some buy not all substances across the membrane |
| High permeability | gases, very small uncharged polar molecules, such as ethanol |
| moderate permeability | water, urea |
| low permeability | polar organic molecules such a glucose |
| very low permeability | ions, charged polar molecules and macromolecules: ATP amino aids, proteins, polysaccharides, nucleic acids (DNA, RNA) |
| passive diffusion | when diffusion occurs through a membrane without the aid of a trnsport proteing |
| transmembrane gradient | concentration of a solute is higher on one side of membrane than the other |
| ion electrochemical gradient | gradients involving ions, dual gradient that has both an electrical gradient and a chemical gradient. |
| passive transport | diffusion of solutes across a membrane that doesn't not require an input of energy. tend to dissipate a preexisting gradient |
| facilitated diffusion | diffusion which involves the aid of transport proteins. |
| isotonic solutions | when the solute concentrations on both sides of the plasma membrane are equal |
| hypertonic | when the solute concentration inside the cell is higher, it is hypertonic relative to the outside of the cell |
| hypotonic | when the solute concentration inside the cell is lower, it is hypotonic relative to the outside of the cell. |
| osmosis | water diffuses through a membrane from the hypotonic compartment into the hypertonic compartment |
| crenation | when water exits the cell via osmosis to equalize the solute concentrations on both sides of the membrane, causing the cell to shrink |
| osmotic lysis | water diffuses into a cell to equalize solute concentrations on both sides of the membrane, The cell may take so much water that it burst... it just got lysised SUCKA |
| osmotic pressure | the hydrostatic pressure required to stop the net flow of water across a membrane due to osmosis. |
| plasmolysis | wilting |
| CHIP 28 experiment | Chip 28 m RNA injected into frog oocytes, occytes placed into a hypotonic medium and observed under a light microscope.. Chip 28 cell burst due to osmotic lysis. |
| aquaporin | new name for CHIP 28 |
| channels | transmembrane proteins that form an open passageway for the facilitated diffusion of ions or molecules across the membrane |
| gated | most channels are gated which meants that they can open to allow the diffusion of solutes and close to prohibit diffusion |
| ligand-gated channels | controlled by the non-covalent binding of small molecules such as hormones or neurotransmitters |
| voltage-gated | he channel opens and closes in response to changes in the amount of electric charge across the membrane |
| mechanosensitive channels | sensitive to changes in membrane tension |
| TRANSPORTERS | aka carriers, bind their solutes and a hydrophilic pocket and undergo a conformational change that switches the exposure of the pocket to the other side of the membrane |
| Uniporters | bind a single molecule or ion and trasport in across the membrane |
| symporters | bind two or more ions or molecules and transport them in the same directions |
| Antiporters | bind two or more ions or molecules and transport them in opposite directions |
| pump | transporter that directly couples its conformational changes to an energy sources, such as ATP hydrolysis Pumps use energy to achieve active transport |
| Active transport | the movement of a solute across a membrane against its gradient. |
| Primary active transport | involves the functioning of pumps that directly use energy to transport a solute, against its gradient |
| secondary active transport | involves the utilization of a preexisting gradient to drive the active transport of a solute |
| electrogenic pump | generates an electrical gradient |
| exocytosis | a process in which material inside the cell, which is packaged into vesicles, is excreted into the extracellular environment |
| endocytosis | plasma membrane invaginates, or folds inward, to form a vesicle that brings substances into the cell |
| clatheryn | makes up the protein coat for endo and exo cytosis |
| receptor-mediated endocytosis | a receptor is specific for a gien cargo, when a receptor binds to that cargo this stimulates the binding of clatheryn to the membrane and initiates the formation of a vesicle. |
| pincoytosis | cell drinking, formation of membrane vesicles from the plasma membrane as a way for cells to internalized extracellular fluid, which allows the cell to sample the extracellular solutes. important in cells that line the intestine in animals |
| phagocytosis | cell eating, involves the formation of an enormous membrane vesicles called a phagosome that engulfs a large particle such as a bacterium. used by macrophages, cells of the immune system in mammals. |
| Turgor pressure | pushes plasma membrane against cell wall Maintains shape and size |
| Transport proteins | enable biological membranes to be selectively permeable |
| 2 Classes of Transport Proteins: Channels and Transporters | |
| Channel types | Ligand-gated Intracellular regulatory proteins Phosphorylation Voltage-gated Mechanosensitive channels |
| Metabolism | Sum total of all chemical reactions that occur within an organism Also refers to specific chemical reactions at the cellular level |
| 2 factors that influence a biological chemical reaction | Direction: Many cells use ATP to drive reactions in one direction Rate: Catalysts called enzyme can speed the reaction rate |
| Energy | Ability to promote change |
| Kinetic | associated with movement |
| Potential | structure or location Chemical energy- energy in molecular bonds |
| First law of thermodynamics | Law of conservation of energy: Energy cannot be created or destroyed Second law of thermodynamics |
| Increase in entropy | favorable |
| Entropy | a measure of the disorder that cannot be harnessed to do work |
| Energy transformations | involve an increase in entropy |
| Total energy | Usable energy + Unusable energy |
| H | G + TS |
| Will a given reaction be spontaneous? | Occur without input of additional energy, Not necessarily fast, Key factor is the free energy change |
| Exergonic | ΔG<0 or negative free energy change, Spontaneous |
| Endergonic | ΔG>0 or positive free energy change, Requires addition of free energy, Not spontaneous |
| ATP Hydrolysis | provides the energy for cellular processes that are endergonic |
| The energy to make ATP | comes from catabolic reactions that are exergonic |
| Activation Energy | required for molecules to achieve a transition state |
| Catalyst | an agent that speeds up the rate of a chemical reaction without being consumed during the reaction |
| Enzymes (are) | protein or RNA catalysts in living cells |
| Enzymes (do) | lower activation energy |
| 3 ways to lower activation energy | Straining bonds in reactants to make it easier to achieve transition state, Positioning reactants together to facilitate bonding, Changing local environment: Direct participation through very temporary bonding |
| Active site | location where reaction takes place |
| Substrate | reactants that bind to active site |
| Enzyme-substrate complex | formed when enzyme and substrate bind together |
| Enzymes have | a high affinity or high degree of specificity for a substrate,Like a lock and key for substrate and enzyme binding |
| Induced fit | interaction also involves conformational changes |
| Prosthetic group | small molecules permanently attached to the enzyme |
| Cofactors | usually inorganic ion that temporarily binds to enzyme |
| Coenzyme | organic molecules that participates in reaction but are left unchanged afterward |
| Enzymes are affected by the environment | Most enzymes function maximally in a narrow range or temperature and pH |
| Overview of metabolism | Chemical reactions occur in metabolic pathways/ Each step is coordinated by a specific enzyme /Catabolic pathways: Result in breakdown and are exergonic /Anabolic pathways: Promote synthesis and are endergonic; Must be coupled to exergonic reaction |
| Catabolic reactions | Breakdown of reactants / Used for recycling / Used to obtain energy for use with endergonic reactions: Energy stored in energy intermediates (ATP, NADH) |
| 2 ways to make ATP | Substrate-Level Phosphorylation, Chemiosmosis |
| Substrate-level phosphorylation | Enzyme directly transfers phosphate from one molecule to another molecule |
| Chemiosmosis | Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi |
| Oxidation | Removal of Electrions |
| Reduction | Addition of electrons |
| Redox | electron removed from one molecule is added to another |
| Electrons removed by oxidation | are used to create energy intermediates like NADH |
| NADH | Oxidized to make ATP / Can donate electrons during synthesis reactions |
| Regulation Metabolic pathways | Gene regulation, cellular regulation, biochemical regulation |
| Gene regulation | turn on or off genes |
| Cellular regulation | cell signaling pathways like hormones |
| Biochemical regulation | competitive inhibitors, noncompetitive inhibitors |
| Competitive inhibitors | compete for access to active site |
| Noncompetitive inhibitors | bind outside the active site |
| Allosteric site | binding causes conformational change in enzyme active site inhibiting enzyme function |
| Feedback inhibition | product of pathway inhibits early steps to prevent overaccumulation of product |
| Cellular respiration | Process by which living cells obtain energy from organic molecules / Primary aim to make energy-storing ATP and NADH |
| Aerobic respiration | uses oxygen / O2 consumed and CO2 released |
| 4 metabolic pathways for Glucose: 1) Glycolysis 2) Breakdown of pyruvate to an acetyl group 3) Citric acid cycle 4) Oxidative phosphorylation | |
| Mitochondrial structure and functions | outer and inner membrane: intermembrane space and mitochondrial matrix / Primary Role is to make ATP / Also involved in synthesis, modification, and breakdown of several types of cellular molecules / can also generate heat in brown fat cells |
| Glycolysis | Glycolysis can occur with or without oxygen Steps in glycolysis nearly identical in all living species 10 steps (reactions) in 3 phases |
| Phases of glycolysis | Energy investment, Cleavage, Energy Liberation |
| Energy investment | 2 ATP hydrolyzed to create fructose-1, 6- biphosphate |
| Cleavage | 6 carbon molecule broken into two 3-carbon molecles of glycerldehyde-3-phosphate |
| Energy Liberation | 2 glyceradldehyde-3-phosphate molecules borken down in to two pyruvate molecules produceing 2 NADH and 4 ATP (2 net ATP) |
| Breakdown of Pyruvate | pyruvate in transported to the mitochondrial matrix / Broken down by pyruvate dehydrogenase / Molecule of CO2 removed from each pyruvate / Remaining acetyl group attached to CoA to make acetyl CoA / 1 NADH is made for each pyruvate |
| Metabolic cycle | Particular molecules enter while other leave, involving a series of organic molecules regenerated with each cycle |
| Citric Acid Cycle | 1) Acetyl is removed from incoming Acetyl CoA and attached to oxaloacetate (OAA) to form citrate or citric acid 2) Series of steps releases 2 CO2, 1 ATP, 3 NADH, and 1 FADH2 3) OAA is regenerated to start the cycle again |
| Oxidative phosphorylation | High energy electrons removed from NADH and FADH2 to make ATP |
| Oxidation Phosphorylation involves | Typically require oxygen, oxidative process involves ETC, Phosphorylation catalyzed by ATP synthase |
| Electron transport chain | Group of protein complexes and small organic molecules embedded in the inner mitcohondrial membrane / Can accept and donate electrons in a linear manner in a series of redox reactions |
| Movement of Electrons in ETC | generates H+ electrochemical gradient (“proton-motive force”) |
| Excess of _______ outside the matrix | positive charge outside of matrix |
| ATP synthase | Enzyme harnesses free energy as H+ flow through membrane embedded region / Energy conversion- H+ electrochemical gradient or proton motive force converted to chemical bond energy in ATP / Rotary machine that makes ATP as it spins |
| Anaerobic metabolism 2 strategies | Use substance other than O2 as final electron acceptor in ETC / Carry out glycolysis only: Pyruvate -> lactic acid in muscles or ethanol in yeast |
| Fermentation | anaerobic and produces far less ATP |
| Primary metabolism | essential for cell structure and function |
| Secondary metabolism | synthesis of secondary metabolites that are not necessary for cell structure and growth: unique to spp or group: defense, attraction, protection, competition |
| 4 categories of secondary metabolites | Phenolics, Alkaloids, Terpenoids, Polyketides |
| Phenolics | antioxidants w/intense flavors and smells |
| Alkaloids | bitter tasting molecules for defense |
| Terpenoids | intense smells and colors |
| Polyketides | chemical weapons |
Created by:
oconnora7
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