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Exam Two
Louisiana Tech University Dr. Kemeage BISC 130
| Question | Answer |
|---|---|
| What is the plasma membrane described by | "Fluid Mosaic Model" |
| What are the "Fluid Mosaic Model" components | Phospholipids Cholesterol Integral membrane proteins Carbohydrates |
| Phospholipids | Form bilayer |
| Cholesterol | Stabilizes bilayer |
| Integral Membrane Proteins | Amino acids interact with hydrophobic lipids to anchor it in the bilayer Many functions |
| Carbohydrates | Glycolipids and Glycoproteins Create hydrophilic coating that attracts water |
| Explain the name "Fluid Mosaic Model" | "Mosaic" because of many components "Fluid" because lipids and proteins are not covalently attached to each other - move laterally |
| Passive Transport | Movement of materials that does not require energy |
| Diffusion | Solutes move from high to lower concentration - "down" their concentration gradient |
| The plasma membrane is | "Selectively permeable" - some atoms and molecules can move across it, but most can not |
| Facilitated Transport | Channel proteins or carrier proteins allow for movement of solutes across plasma membrane, down their concentration gradient |
| Facts about channel proteins and carrier proteins | Channels are faster than carriers Can be always open or gated by specific mechanisms Are very specific for the atom/molecule they transport Example - Aquaporin |
| Osmosis | Movement of WATER through semipermeable membrane from an area of low solute concentration to an area of higher solute concentration |
| Due to aquaporins | plasma membrane allows movement of water via osmosis in or out of the cell - movement of water depends on the amount of solutes in the surrounding concentration |
| What are the 3 types of solutions | Hypotonic Hypertonic Isotonic |
| Hypotonic Solution | Surroundings have fewer solutes than inside of cell Water moves into cell - cells swell, can burst Bad for animal cells, good for plant cells |
| Hypertonic Solution | Surroundings have more solutes than inside of cells Water moves out of cell - cells shrivel Bad for cells |
| Isotonic Solutions | Surroundings have same amount of solutes as inside of cell No net movement of water Good for animal cells, bad for plant cells |
| Active Transport | Movement of materials that requires energy Moves materials against concentration gradient From low to high concentration |
| Bulk Transport | Active transport of large structures/quantities 2 Types - endocytosis and exocytosis |
| Endocytosis | Enters in vesicles/vacuoles Phagocytosis for large particle, pinocytosis for many small particles |
| Exocytosis | Exits from vesicles |
| Energy | The ability to do work 2 types - Potential and Kinetic |
| Potential Energy | Stored Energy Includes chemical energy (energy in chemical bonds) *Breaking chemical bonds release energy |
| Kinetic Energy | Energy of motion Includes heat |
| First Law of Thermodynamics | Energy cannot be created or destroyed Only converted from one form to another |
| 2 types of chemical reactions | Exergonic and Endergonic |
| Exergonic reactions | Products are at lower energy than reactants release energy |
| Endergonic reactions | Products are at higher energy than reactants require input of energy |
| Facts about Exergonic and Endergonic reactions | The two can be coupled Both need to overcome activation energy to proceed - (prevents reactions from spontaneously occurring) Heat energy can be used to overcome activation energy - (not feasible in cells |
| Catalyst | Holds reactions and strains chemical bonds to lower activation energy Can facilitate exergonic or endergonic reactions Biological catalysts (most are protein) are called enzymes |
| Enzymes Catalyst Steps | 1) Substrate(s) bind at enzyme's active site 2) Enzyme changes shape slightly to better fit substrates 3) Chemical reaction occurs 4) Product(s) released 5) Enzymes assumes original shape |
| Enzymes Catalyst step one | Substrate(s) bind at enzyme's active site - form enzyme/substrate complex - enzymes are very specific for their substrates |
| Enzymes Catalyst step two | Enzyme changes shape slightly to better fit substrates - "induced fit" - strains chemical bonds in substrate(s) lowering activation energy - for exergonic reactions, ambient heat energy is now enough to overcome activation energy |
| Enzymes Catalyst step five | Enzymes assumes original shape - Not altered by reaction (free to work again) |
| Enzyme Inhibators | Reduce an enzyme's function |
| Enzyme activators | increase an enzyme's function |
| Some enzymes require | cofactors and coenzymes to function |
| It takes a series of steps to build or break down a complex molecule. Each step carried out by a single enzyme called | Metabolic Pathways |
| What are the two types of Metabolic pathways | Anabolic Catabolic |
| Anabolic Pathway | Build complex molecules Require energy input |
| Catabolic Pathway | Break down complex molecules Release energy |
| ATP: Adenosine Triphosphate | A nucleotide Has chemical potential energy (2 high-energy bonds btw 3 phosphate groups) Breaking them releases energy (exergonic) Coupled to endergonic reactions to provide the energy they need |
| ATP is the "what" of the cell | The energy currency |
| ATP chemical equation | ATP -> ADP + Pi -> AMP + Pi (-> represents energy) |
| Problems of ATP | Unstable Energy is stored long term in other molecules, converted to ATP for use |
| Electrons have what kind of energy | Potential energy |
| Loss of electrons | Oxidation Lowered energy |
| Gain of electrons | Reduction Higher energy |
| Oxidations and reductions are coupled | Redox reactions |
| Along with electrons what else is transferred | H+ ions |
| Electron carriers | Some organic molecules readily gain or lose electrons Example - NAD+ (oxidized) and NADH (reduced) |
| Electrons can be at what kind of energy states | High or low |
| Cellular Respiration | The complete breakdown and oxidation of glucose to generate ATP Several Stages |
| Cellular Respiration chemical formula | C6H12O6 + O2 -> CO2 + H2O + energy |
| Glycolysis | 10 - enzyme metabolic pathway Glucose -> Pyruvate X2 (6-carbon) (3-carbon) ATP is spent in initial step, but a net amount is generated NAD+ reduced to NADH In Cytoplasm In Eukaryotes, all further steps in the mitochondria |
| Pyruvate Oxidation | Pyruvate broken down, oxidized and attached to Coenzyme A (CoA) Releases CO2 Generates NADH Results in acetyl (CoA) |
| The Citric Acid Cycle | Acetyl group (2 carbons) transferred from CoA to oxaloacetate (4 carbon) to form citrate (6 carbon) In many steps, citrate is broken down and oxidized until it is back to oxaloacetate CO2 X2 release ATP generated NADH generated FAD reduced to FADH2 |
| Electron Transport Chain (ETC) | NADH and FADH2 are oxidized back to NAD+ and FAD Energy from electrons used to pump H+ across the membrane *H+ cannot diffuse across the membrane |
| Step One of ETC | NADH and FADH2 are oxidized back to NAD+ and FAD - their high-energy electrons passed through a series of other electron carriers -lose energy with each transfer - Finally transferred to O2 as low energy electrons |
| Step Two of ETC | Energy from electrons used to pump H+ across the membrane - Active Transport - creates "protein gradient" |
| ATP Synthase | A large multi-protein complex Spans the membrane Allows H+ to pass through down the concentration gradient Powers rotation of stalk, which generates ATP *Proton gradient is required for this to work *Most of ATP from cell respiration made here |
| Catabolism of Other Carbohydrates | Broken monosaccharides, enter glycolysis |
| Catabolism of Proteins | Broken to amino acids, enter glycolysis, pyruvate oxidation or citric acid cycle |
| Catabolism of Lipids/ Fatty Acids | Broken into 2- carbon units, enter citric acid cycle |
| Categories of Organisms | Heterotrophs and Autotrophs including Photoautotrophs (example: plants, some protists, some bacteria) |
| Chemical Formula for Photosynthesis | CO2 + H2O + light -> C6H12O6 + O2 |
| Photosynthesis | 2 Parts: Light-Dependent Reactions and Light-Independent Reactions *In Eukaryotes, virtually all steps in chloroplasts |
| Light-Dependent Reactions (LDR) | Require light |
| Light-Independent Reactions (LIR) | Do not require light |
| What is visible light a type of | Electromagnetic Radiation - Has specific wavelength - Different colors of visible light have different wavelengths |
| Light has what types of nature | Wave and Particle -Particles of light are called photons - Carry Energy |
| Pigment | Example: Chlorophylls: harness energy from photons for photosynthesis Example: Carotenoids: Dispose of excess energy |
| Hundreds of chlorophylls and carotenoids arranged into what | light harvesting complexes - part of photsystems |
| The LDR Step One | Photons strike pigments in photosystem II, excite electrons of chlorophylls to a higher energy state |
| The LDR step two | Energy of excited electrons passed from one chlorophyll to another until it reaches the Reaction Center (RC) chlorophyll |
| The LDR step three | RC chlorophyll delivers high-energy electrons through an electron transport chain - RC chlorophyll replaces lost electrons from H2O - H2O -> O2 + e- |
| The LDR step four | High energy electrons passed through series pf carriers, lower energy with each passing - energy used to pump H+ across the membrane - Creates proton gradient - Used by ATP synthase to generate ATP |
| LDR step five | Low energy electrons arrive at the photosystem I's RC chlorophyll |
| LDR step six | Photons excite electrons in photosystems I's chlorophylls, energy moves to RC chlorophyll |
| LDR step seven | High energy electrons in photosystem I used to reduce NADP+ to NADPH (electron carriers) |
| LDR overview | H20 + photons -> O2 + ATP + NADPH |
| The LIR | Takes place in the stroma (cytoplasm of chloroplast) Steps 1-3 are called the Calvin Cycle |
| LIR Step One | An enzyme call RuBisCO performs carbon fixation by attaching CO2 to Ribulose Bisphosphate (5 carbons), creating 3- phosphoglyceric acid (3-PGA) X 2 |
| LIR Step Two | ATP and NADPH used to reduce 3-PGA to Glyceraldehyde |
| LIR Step Three | ATP used to regenerate Ribulose Biphosphate from some G3P |
| LIR Step Four | In cytoplasm, some G3P used to build amino acids, lipids, sugars - Converted to glucose through glycolysis - Same enzymes from cell respiration working in reverse |
| LIR Overview | CO2 + ATP + NADPH -> C6H12O6 |
| Ligands | Released from signaling cells Bind to receptor proteins on target cells |
| 4 types of Signaling Mechanisms | Autocrine Direct Signaling Paracrine Endocrine |
| Autocrine | Ligand binds to receptor on the signaling cell |
| Direct Signaling | Ligand travels from cytoplasm to cytoplasm from signaling cell to target cell |
| Paracrine | Ligand binds to receptors on nearby cells |
| Endocrine | Ligand binds to receptor on distant cells Stable ligand ensures it can travel across the body |
| 2 types of receptors | intracellular receptor Cell surface receptors |
| Intracellular Receptors | receptor protein in cytoplasm of cell ligands for these receptors must be small and hydrophobic to diffuse across the membrane Example - steroid hormones |
| Cell surface receptors | Receptor protein on surface of cell Anchored in plasma membrane Must possess 3 Distinct membranes: Extracellular Domain Cytoplasmic Domain Transmembrane Domain |
| Extracellular Domain | Exposed to outside of cell Binds ligand |
| Cytoplasmic Domain | Exposed to cytoplasm |
| Transmembrane Domain | Spans membrane |
| Cell Surface Receptors example | Small molecules pr proteins *Ligands for these receptors are water-soluble |
| Signal Transduction | Binding of ligand to change in shape of receptor (behaves differently) Example: an intracellular receptor may enter nucleus, causes genes to be turned on/off Example: May lead to release/creation of a second messenger |
| Phosphorylation | Modification of protein by the addition of a phosphate group from ATP Catalyzed by a class of enzymes called kinases |
| Dephosphorylation | Removal of a phosphate group from a protein Catalyzed by a class of enzymes called phosphates |
| Function of a protein can be switched on/off depending on its | phosphorylation site |
| Signal transduction can ultimately result in | Altered cell behavior cell growth/division Apoptosis |
| Single celled yeasts secrete a | "mating factor" ligand to find yeasts cells to mate with Example: Quorum sensing - released ligands (autoinducers) communicate cell density to other bacteria -some bacteria can form biofilms, but this requires high cell density |
| Quorum sensing | low ligand density |
| Ligand diffuses - no response | High ligand density |
| Signaling pathway activated | formation of biofilms |
| Aquaporin: | a channel protein that allows water through the membrane at a very high rate |
| Carrier protein | a membrane protein that moves a substance across the plasma membrane by changing its own shape |
| Channel protein | a membrane protein that allows a substance to pass through its hollow core across the plasma membrane |
| Endocytosis | type of active transport that moves substances into a cell |
| Exocytosis | a type of active transport that moves substances out of a cell |
| Glycolipid: | combination of carbohydrates and lipids |
| Glycoprotein | a combination of carbohydrates and proteins |
| Solute | a substance that is dissolved in a liquid to form a solution |
| Coenzyme: | a small organic molecule that is required for optimal enzyme activity |
| Cofactor: | an inorganic ion that is required for optimal enzyme activity |
| Metabolism: | all of the chemical reactions that take place inside cells, including anabolic and catabolic pathways |
| Autotroph: | an organism that gets carbon from inorganic sources |
| Carbon fixation | the process of converting inorganic CO2 gas into organic compounds |
| Heterotroph | an organism that consumes organic substances or other organisms for carbon |
| Photoautotroph | an organism capable of producing its own organic compounds from inorganic carbon and energy from sunlight |
| Pigment | a molecule that is capable of absorbing certain wavelengths of light and reflecting others |
| Apoptosis: | programmed cell death |
| Biofilm | a matrix of proteins and sugars that protects colonies of pathogenic bacteria from the host immune system |
| Ligand: | a molecule produced by a signaling cell that binds with a specific receptor, delivering a signal in the process |
| Second messenger | a small, non-protein molecule that propagates a signal within the cell after activation of a receptor causes its release |
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Scarlettblanchard3
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