Bio Chapter 5

Book Notes (Homework)

5.1 Membranes are fluid mosaics of lipids and proteins with many functions- Gases and water can go through cellular membranes Fluid mosaic models are models of cell membrane structure showing the proteins suspended in phospholipid fluid as a mosaic Shows structure and function Diffusion and osmosis are forms of passive transport Selective permeability is when a membrane only allows certain things to pass through Selective permeable membranes require proteins to regulate substances that enter and exit Can you identify six different types of functions of proteins in a plasma membrane? 5.2 The spontaneous formation of membrane was a critical step  in the origin of life Phospholipids are the key ingredients in a biological membrane Probably first organic molecule to form Self-assemble into membranes Phospholipid bilayer form with phospholipids and water Membrane can enclose substance different than surrounding In the origin of a cell, why would the formation of a simple lipid bilayer membrane not be sufficient? What else would have to be part of such a membrane? Need proteins to regulate selective permeability 5.3 Passive transport is diffusion across a membrane with no energy investment Diffusion is the tendency of molecules to spread out in available space The area along where the density of a substance increases or decreases is called the concentration gradient Equilibrium is what a substance strives for with diffusion 2+ substances diffuse separately Why 2 molecules originally might go in seperate directions Higher concentration on one side, lower concentration on the other, want to get to the lower concentration to attain equilibrium Passive transport occurs across a membrane Ions and polar molecules can diffuse across hydrophobic membranes by moving down in concentration gradient/if they have transport proteins Why is diffusion across a membrane called passive transport? It requires no energy from the cell, only uses kinetic energy     5.4 Osmosis is the diffusion of water across a membrane Water is one of the most important substances to cross a membrane because... Water keeps the balance between a cell and environment Diffusion of water across selectively permeable membrane is called osmosis 5.5 Water balance between cells and their surroundings is crucial to organisms Tonicity is the ability of the solution surrounding a membrane to make a cell gain or lose water Depends on concentration gradient Cells are covered different solutions to monitor water movement Isotonic solutions ceases net water movement into or out of a cell Hypotonic solutions are solutions which cause cells to take in water Hypertonic solutions cause cells to expunge water The control of water balance is called osmoregulation Turgid: very firm (Non-woody plants need turgid cells for support) Turgor pressure: back pressure Flaccid: limp Plasmolysis: plants losing water and shrivelling and pulling away from the cell wall 5.6 hydrophobic/polar molecules require transport proteins Passive transport to move down the concentration gradient Facilitated diffusion is passive transport, moving down the concentration gradient Provides channel for specific molecules Carrier proteins carry proteins through phospholipid bilayer Polar molecules diffusion (such as osmosis) is slow because the hydrophobic tails of the phospholipid bilayer 5.7 Research can lead to unplanned discoveries Dr. Agre discovered abundant protein in cell membranes on accident Used frog eggs to test to see if protein made up water passageways to speed osmosis Theory seems to be true- named proteins aquaproteins Aquaporins allow only water to pass through Aquaporins can contribute to kidney, eye, and brain Researching aquaporins can lead to medical solutions 5.8 Active transport moves a solute up its concentration gradient ATP provides energy for active transport Sodium Potassium pumps are a form of active transport Active transport let’s cells keep different environments Nerve signals depend on cell environment differences 5.9 Exocytosis release molecules from a cell through the cell membrane (EXIT) Transport vesicles track: from golgi body Merges with plasma membrane Pinocytosis Cellular drinking Endocytosis helps molecules enter the cell via the cell membrane 2 types of endocytosis: Phagocytosis: pseudopodia wrap around molecules Vacuole merges w/ lysosome Digests molecules “Cellular eating” receptor-mediated endocytosis: specific solute transports Specific molecules trigger plasma membrane to indent and pinch closed around molecules, bringing them inside the cell Can take in cholesterol for blood creation Lipoproteins (LDL) bind to receptors Enter endocytosis receptor-mediated endocytosis Lack of LDL can lead to diseases Because of build up of cholesterol   5.10 Forms of energy Energy capacity to cause change/to do work Kinetic energy is the energy of motion Motion onto matter Potential energy is the energy all matter possesses Water behind a dam Energy (like matter) is conserved Cannot be created or destroyed Every time energy is used, some is lost as heat Food provides covalent energy when bonds are broken Chemical energy potential energy could be released in chemical reaction Energy Transformations Study of energy transformations = thermodynamics 1st law of thermodynamics Law of energy conservation Energy in universe is consistent, forms change Recycling energy is impossible due to the give-off of heat Entropy is the measurement of disorder 2nd law of thermodynamics Every energy conversion adds disorder aka entropy Cellular respiration is the chemical energy stored to make ATP   5.11 Exergonic reactions Energy outward Much potential energy used Reaction released energy equal in amount to which was used in reaction Endergonic reactions Energy outward Little amount of potential energy Photosynthesis Metabolism: total number of chemical reactions in an organism Metabolic pathway: series of chemical reactions to build or break molecules EVERYTHING REQUIRES ENERGY Coupling: use of energy from exergonic reactions   5.12 Atp: Adenosine triphosphate Negatively charged phosphate groups Unstable bonds: breaks make ADP Phosphate transfer from ATP to other molecule is called phosphorylation (powers endergonic synthesis) ATP makes active transport possible Renewable source: Cells regenerate ATP Energy from exergonic reaction → generates ATP Endergonic bonding of phosphate to ADP → ATP 10 million ATP molecules per second 5.13 Enzymes speed chemical reactions by lowering energy barriers Energy has to be absorbed to break reactant bonds Activation energy: Amount of energy needed to make reactants less stable Activation energy prevents spontaneous breakdown of molecules- Break by adding heat Enzymes: molecules that increase reaction speed without being in the reaction All enzymes are proteins, except RNA which can be an enzyme Lower activation energy Lower the barrier, faster the chemical reaction 5.14 Enzymes are specific for specific reactions: aka lock and key Specific reactant for an enzyme labeled substrate Substrate fits into active site (indent on enzyme surface) Catalytic Cycle Empty active site Substrate enters active site connection, known as induced fit can contort molecules Strained bond reacts with water, substrate converts into products Enzymes release products, do not change Single enzyme can act w/ millions of substrates per second Optimal Conditions for Enzymes Shape affects substrate Temperature: rate of contact between reactants and acyive site Higher temps. denature/destroy function Alter shape, substrates do not fit 6-8 ph for the same reasons as stated above Cofactors Cofactors are non-proteins that assist enzymes inorganic/non-living (ex. ions) Organic cofactor = coenzyme All metabolic pathways function at once would create chemical chaos; cofactors regulate metabolism 5.15 Inhibitors limit enzyme activity Competitive inhibitors block substrates from getting to the active sites Non-competitive inhibitors do not block active site Inhibitors regulate metabolism: overproduction leads  to blockage feedback inhibitors

Powerpoint Presentation Notes (Classwork)

5.1 Fluid mosaic model describes membrane structure Selective permeability Transport proteins allow certain proteins to enter/exit cell Enzymes carry out sequential reactions Attachment proteins support cell membrane Receptor proteins activate molecules inside cells Junction proteins attach cells to each other Glycoproteins identify cells to one another 5.2 Phospholipids make membranes 5.3 Diffusion is the random spreading of molecules Passive transport moves down a concentration gradient 5.4 Water moving across a membrane is called osmosis 5.5 Tonicity ability of cell/solution to gain/lose water Hypertonic: more Hypotonic: less Isometric: equal

Study Guide

Fluid Mosaic Model:               "diverse protein molecules suspended in a fluid phospholipid bilayer" Selective Permeability:          "allows certain substances to pass through" 6 Proteins:          attatchment: Extracellular Matrix, Cytoskeleton          junction: long-term attatchment of cells\          glycoproteins: sugar identification          transport: move ions and molecules          receptor: bind signaling molecules and activate others          enzymes: catalyze chemical reactions Diffusion: random spreading of molecules in available space Facilitated Diffusion: passive transport driven by concentration gradient, TRANSPORT PROTEINS Concentration Gradient: "A region along which the density of a cell increases or decreases" Passive Transport: movement that does not require ATP/cellular work Active Transport: movement of molecules using ATP     Exocytosis: getting out of the cell     Endocytosis: taking into the cell  

Osmosis: diffusion of water  Tonocity: ability of solution surounding cell to affect water levels      hypotonic: less concentrated      hypertonic: more concentrated      isotonic: equally concentrated Osmoregulation: control of water: contractile vesicles Aquaporin: channel that allows water molecules to pass through Energy: abilkity to cause change          Exergonic Reactions: release energy, higher potential energy in reactants than products, CELLULR RESPIRATION       Endergonic Reactions: store energy, products have more energy than the reactants, PHOTOSYNTHESIS

End of Chapter Questions

(a) active transport (b) concentration gradient (c) nonpolar molecules (d) facilitated diffusion??? (e) proteins

(a) enzyme (b) active site (c) substrate (d) induced fit  (e) converted to products (f) products released  

8.          chemical, transport, mechanical. Chemical: adding phosphates to ADP provides energy for endergonic reactions Transport: ATP is used in active transport Mechanical: Cell contraction 9.          Enzymes lower ctivation energy by weakening bonds to a more attainable level of instablity for a chemical reaction to sever.  10.         Matter cannot be created or destroyed/ energy cannot be created or destroyed. Matter/ energy are passed through Food chains 11.          Proteins scattered throughout cell membranes decide how the membrane will functions 12.         If an enzyme is ove producing a product, inhibitors ca slw or stop the reacton from occuring, letting the cell have time to recuperate. 13.          hot day: need to regain water after losing it through sweat 14.          Ask for help    

MCAS Study Guide