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135 Cards in this Set
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Plasma Membrane: Phospholipids |
made of glycerol with a phosphate group and two fattyacids attached to it. The phosphate group is polar and the two fatty acid tails are nonpolar. When placed in water, the polar heads (which are hydrophilic) orient themselves with the water in a bilayer with the polar heads facing the outer surface and facing the inner surface of the bilayer. The nonpolar tails (which are hydrophobic) are located inside the bilayer (between the polar heads) forming their own nonpolar environment away from the water. This bilayer arrangement creates a unique barrier. Any molecule that wants to get inside the cell (or move outside the cell) must pass through both hydrophilic and hydrophobic regions. Most larger molecules and charged molecules cannot do this.
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Steroids
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are embedded in the phospholipid bilayer. They function strengthening and stiffening the membrane (adds stability to the membrane) and helps maintain the fluidity of the membrane. Animals have cholesterol, fungi have ergosterol and plants have phytosterol.
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Carbohydrates (include glycolipids and glycoproteins)
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carbohydrates are found in the membrane attached to proteins or lipids
Glycolipids – are lipids with carbohydrate groups attached. They are similar to phospholipids except the phosphate group is replaced with a carbohydrate group. Glycoproteins – proteins with carbohydrate groups attached. The glycolipids, along with glycoproteins form the glycocalyx – a sticky area on the outside of the cell. The glycocalyx functions in cell identification and helps cells stick together. |
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Integral proteins
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are embedded in the membrane
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Peripheral proteins
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are found on the outside or inside of the membrane.
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channel proteins
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are hollow proteins that allow small molecules to pass freely through the membrane. Only molecules that fit through the channel can pass through channel proteins.
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carrier proteins
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are proteins designed to bind a specific molecule and transport it across the membrane.
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cell recognition proteins |
are usually glycoproteins. Act as identification markers or “name tags” for the cell. These proteins identify the cell as “self”. Any “nonself” or “foreign” cells will be destroyed by the immune system. This is why a person who receives an organ transplant will have to take drugs to suppress their immune system or that organ will be rejected.
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receptor proteins
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These proteins bind specific extracellular molecules and then cause some time of cellular reaction in response. Example: Insulin receptors on cells bind insulin (a hormone). When insulin binds to the insulin receptor, this triggers the cell to begin taking in glucose.
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enzymatic proteins
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Some membrane proteins act as enzymes and carry out chemical reactions.
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junction proteins
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Proteins that help join animal cells together or provide some sort of bridge between animal cells. These are discussed in more detail at the end of this assignment.
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Impermeable
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nothing can pass through the membrane
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Freely permeable
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everything can pass through the membrane
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Semipermeable or selectively permeable
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the membrane would allow certain materials to cross while blocking others. It acts like a gatekeeper – letting certain materials in and certain materials out while blocking the passage of other materials.The plasma membrane is semipermeable or selectively permeable. If it were impermeable it would have no way to bring in food or get rid of waste. If it were freely permeable, it would lose everything it wanted to keep.
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concentration gradient
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difference in concentration of a solute. Solutes tend to move down a gradient from a high concentration to a low concentration. Solutes that move against the gradient (from low concentration to high concentration) require energy to do so
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solution
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a mixture of two of more substance that is equal throughout.
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solute
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a component in a solution that is present in the lesser amount.
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solvent
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a component in a solution that is present in the greater amount. For living organisms, the solvent inside and outside of cells is water.
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Describe the process of diffusion.
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The movement of a molecule from a high concentration to a low concentration. The term simple diffusion usually refers to the diffusion of a molecule directly through the membrane (through the phospholipid bilayer). This process does not require ATP.
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Define the terms osmosis and tonicity. Describe the following types of osmotic solutions including how each would affect an animal cell and a plant cell.
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Osmosis is the diffusion of water through a semipermeable or selectively permeable membrane. Osmosis does not require ATP.Tonicity is the ability of a solution to change the shape of a cell. There are three types of “tonic” solutions that can be defined by their ability to change the shape of a cell. These solutions are also defined by the concentration of their solutes. Remember that the higher the concentration of the solutes, the lower the concentration of water and the lower the concentration of the solutes, the higher the concentration of water.
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Isotonic solution
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a solution with the same concentration of solutes as the cell. Cells do not change shape in an isotonic solution.
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animal cell
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does not cause a change in the shape animal cells. This is the desired condition for animal cells.
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plant cell
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does not cause a change in the shape of plant cells. This is not really the desired condition for plant cells. They prefer to be full of water. In the isotonic conditions, plant cells are said to be flaccid.
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Hypotonic solution
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a solution with a lower concentration of solutes than the cell. This results in water moving from a high concentration (outside the cell) to a lower concentration (inside the cell). This will cause the cell to expand in size.
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animal cell
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Hypotonic solutions cause animal cells to swell and lyse (burst).
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plant cell
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Hypotonic solutions do not causes lysis in plant cells because they have cell walls. Hypotonic solutions cause the central vacuole to increase in size and causes turgor pressure in the cell (the cell becomes turgid). This is important in helping support the plant and keeping it upright. Compare a wilted plant to a well watered plant.
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Hypertonic solution
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a solution with a higher concentration of solutes than the cell. This results in water moving from a high concentration (inside the cell) to a lower concentration (outside the cell). This will cause the cell to shrink in size.
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animal cell
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Hypertonic solutions cause animals cells to crenate (shrivel or shrink).
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plant cell
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Hypertonic solutions do not cause shriveling of a plant cell, again because of the cell wall. In a plant cell, as the central vacuole loses water, the plasma membrane pulls away from the cell wall and the cytoplasm pulls inward. This is called plasmolysis. This will cause the plant to lose support and wilt.
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Facilitated Transport (Facilitated Diffusion)
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is the diffusion of molecules that cannot pass directly through the lipid bilayer. This process requires the help of carrier proteins. This process does not require ATP.
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Active transport
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is the movement of molecules from a low concentration to a high concentration with the help of carrier proteins and with the use of ATP. This is an “active” process and requires the input of energy. |
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Exocytosis
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the movement of materials from the inside of the cell to the outside of the cell using a membrane bound vesicle. Can be excretion (getting rid of waste) or secretion (releasing a usable product such as mucus, hormones, or digestive enzymes). Exocytosis is an active process and requires ATP.
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Endocytosis
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the movement of materials from the outside of the cell to the inside of the cell using a membrane bound vesicle. There are three types of endocytosis: phagocytosis, pinocytosis and receptor-mediated endocytosis. All types of endocytosis are active processes and require ATP.
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Phagocytosis
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involves taking in large particles using pseudopods (cellular extensions ofthe membrane). Pseudopod means false feet but I prefer to think of them more as false arms. This process is nicknamed “cell eating”.
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Pinocytosis
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involves taking in small or dissolved particles by forming a “pit” and taking in whatever particles gets pulled into the pit. This process is nicknamed “cell drinking”.
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Receptor-mediated endocytosis
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a form of pinocytosis where receptors in the plasma membrane bind the desired molecules and then a pit forms and brings them inside the cell. This allows the cell to select what it brings in, rather than just randomly pulling particles into the pit.
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Extracellular matrix
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made of polysaccharides and proteins and is found between cells. Collagen is a protein fiber that can give the matrix strength. Elastin is a protein fiber that can give it flexibility. Fibronectins and laminins are adhesive proteins that can help cells stick together.
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Adhesion junction
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Consists of plaques on the inside of each cell with filaments joining the cells attached to the plaques. Filaments from the cytoskeleton are also attached to the plaques. This type of junction is very strong but flexible. It can be found between the cells in your skin, in the heart, bladder and other organs. Creates a sturdy, flexible sheet of cells.
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Desmosome
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A desmosome is an adhesion junction where internal cytoplasmic plaques are firmly attached to the cytoskeleton. These plaques are also attached to filaments that attach two adjacent cells together. Creates a strong connection for a sheet of cells.
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Hemidesomosome
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an adhesion junction that is a single point of attachment between cells or between cells and extracellular matrix.
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Tight junctions
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consist of proteins that rivet to cells together in a zipper-like fashion. Tight junctions are just as they are named – tight. These junctions do not let materials pass between the cells. For example – these junctions are found between the cells in the digestive tract. This keeps the digestive enzymes away from the inner cells of the digestive tract. Otherwise, you would digest your own organs!
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Gap junctions
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a. are junctions made of a group of proteins formed into circle with a small passageway in the middle. These join cells together but also allow small molecules to pass between cells. They allow communication between cells. For example gap junctions in heart muscle allow the electrical impulse to travel from one cell to another and allow the heart to contract as a unit.
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Primary cell wall
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All plant cells have a primary cell wall that is made of cellulose and pectins that allow the primary wall to be flexible.
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Secondary cell wall
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Some plant cells also have secondary cell walls that contain many layers of cellulose. The secondary wall is more rigid and is not as flexible. The secondary cell wall in seen in plant cells in “woody” parts of the plant such as trunks and branches.
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Plasmodesmata |
membrane lined channels that pass through the cell wall and connect plant cells together. The plasmodesmata allow the passage of water and small solutes between plant cells. This allows some equalization of water pressure in the plant.
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Kinetic Energy
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the energy of motion
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Potential Energy
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stored or inactive energy
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Mechanical energy
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energy involved in moving matter (example – your muscles exhibit mechanical energy)
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Electrical energy
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energy in the movement of charged particle (example – nerve impulses)
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Radiant energy
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energy that moves in waves (example – heat)
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Chemical Energy
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energy stored in chemical bonds (example – ATP)
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First law of thermodynamics
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energy cannot be created or destroyed, but it can be changed from one form to another.
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Second law of thermodynamics
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energy cannot be changed from one form to another without a loss of usable energy. In living systems, energy is lost in the form of heat.
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Entropy
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the relative amount of disorder or disorganization. Each energy transformation that occurs increases the amount of entropy (disorder) in the universe. Therefore, the entropy in the universe is continually increasing.
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Reactants
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the substance(s) that participate in the reaction. What you begin the reactionwith.
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Products
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the substance(s) that are produced by the reaction. What the reaction ends with.
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Reversible reaction
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reversible reactions can go in both directions. Reactants can produce products and produces can produce reactants. It is important to note that all chemical reactions are theoretically reversible but in reality some are more reversible that others.
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Chemical equilibrium
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occurs when amount of reactants and products are constant. In other words they are not changing anymore. They are not necessarily equal but they are constant. For example one reaction might reach equilibrium when 70% of the material is in the form of reactants and 30% in products while another reaction might reach equilibrium when 5% of the material is in the form of reactants and 95% is in the form of products.
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Endergonic reaction
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requires the input of energy for the reaction to occur
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Exergonic reaction
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these reaction produce energy
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Coupled reaction
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energy released by exergonic reactions are used to power endergonic reactions
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Biosynthetic pathway
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metabolic pathways that build larger molecules from smaller molecules
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Degradative pathway
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metabolic pathways that break down molecules
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ATP
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Structure: See figure 3.21 in your textbook. You can also refer to figure 6.3 in Chapter 6. Note that the bonds between the phosphates are high energy bonds because the phosphates have a negative charge and are pulling away from each other.
Function: to store energy in the phosphate bonds. The energy in ATP is only released when a high energy phosphate bond is broken. This energy is used for: chemical work – used to synthesize macromolecules transport work – used to move materials across the plasma membrane (example – active transport, phagocytosis etc.) mechanical work – used to contract muscles, move cilia and flagella etc. |
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Enzymes
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proteins that act as biological catalysts. They speed up chemical reactions.
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Four characteristics common to all enzymes
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1. All enzymes are proteins.
2. All enzymes are biological catalysts that speed up chemical reactions. However, enzymes will not cause a chemical reaction to occur that would not occur naturally 3. All enzymes are specific for their substrate (a substrate is a substance that the enzyme acts upon). 4. All enzymes simply help a chemical reaction occur (therefore they speed up chemical reactions). However, the enzymes does not become part of the product and is not used up by the reaction. |
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Energy of activation
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the energy that must be added to cause molecules to react with each other
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Substrate
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the substance that the enzyme acts upon
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Active site
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the place on the enzyme where the substrate binds
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Enzyme-substrate complex
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the combination of the enzyme and substrate where the substrate enters and bind to the active site on the enzyme.
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Lock and key model
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the older (and incorrect) model of how the enzyme and substrate fit together. In this model they fit exactly together like a lock and key.
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Induced fit model
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the current model in which the substrate enters the active site and the active site molds around the substrate.
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Substrate concentration
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the more concentrated the substrate the faster the enzyme will react.
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Enzyme concentration
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the more concentrated the enzyme, the faster the reaction will occur
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Temperature
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enzymes work better with warmer temperatures. However, if temperature rises too much, the enzyme could be denatured and not be usable.
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pH
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enzymes work better at a neutral pH. However, if the pH becomes extremely basic or extremely acidic, the enzyme could be denatured and not be usable.
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Cofactors - “enzyme helpers”.
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These are molecules that are necessary for an enzyme to function. Cofactors are inorganic ion or organic (but nonprotein) molecules.
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Coenzymes
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The term Coenzyme is usually given to the organic (but nonprotein) cofactors. They are the organic enzyme helpers.
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Competitive inhibition
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where a molecule binds to the active site and prevents the substrate from binding.
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Noncompetitive (allosteric) inhibition
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where a molecule binds to the enzyme and changes the shape of the active site and prevents the substrate from binding. The allosteric site is where the non-competitive inhibitor binds.
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Feedback inhibition
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Where the end product of a metabolic pathway binds to the enzyme and prevents it from binding with its substrate.
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Enzyme Activity – enzymes work by the enzyme cycle.
Enzyme + Substrate → Enzyme substrate complex → Product + Enzyme ↑ ←←←←←←←←←←←←←←←←←←←←←←←←← ↓ Notice that the enzyme is recycled and can become be used again and again. It is not used up by the reaction and it does not become part of the product. |
Enzyme Activity – enzymes work by the enzyme cycle. Enzyme + Substrate → Enzyme substrate complex → Product + Enzyme ↑ ←←←←←←←←←←←←←←←←←←←←←←←←← ↓Notice that the enzyme is recycled and can become be used again and again. It is not used up by the reaction and it does not become part of the product. |
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Oxidation
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the loss of electrons from a molecule |
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Reduction
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the gain of electrons from a molecule
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Electron transport chain
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also called an Electron transport system – usually abbreviated ETS. Is a series of membrane bound carriers that pass electrons from one carrier to another. We are going to see ETS’s coupled with an enzyme called ATP synthase that will be used to produce ATP.
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Photosynthesis
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in living things, hydrogen ions (H+) often accompany electrons. Photosynthesis uses oxidation/reduction reactions to transfer electrons (and hydrogen ions) from water to carbon dioxide to make glucose.
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Cellular respiration
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This reaction is the reverse of photosynthesis. Glucose loses hydrogen ions (and electrons) and produces carbon dioxide and water. In the process energy is released and is used to make ATP (primarily in the mitochondria).
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photosynthesis
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Photosynthesis is the process by which carbon and energy enter the web of life. Is the process that uses sun energy (radiant energy) to take carbon dioxide and water and produce oxygen and glucose. Photosynthesis consists of light dependent and light independent reactions (sometimes called light and dark reactions)
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Autotrophs
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can produce their own food (their own glucose) from carbon dioxide and water
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Photoautotrophs
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use photosynthesis to produce glucose. Use radiant energy.
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Chemoautotrophs
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use chemical reactions to produce glucose (chemical energy)
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Heterotrophs
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organisms that must consume organic molecules (carbohydrates, lipids, proteins) made by other organism. (must eat plant or animal materials)
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Stomata
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small openings in a leaf that allows air to enter. These are controlled guard cells that lie on each side of the opening. Air can enter but unfortunately water can exit. So the plant can open the stomata to allow air to enter or close them when the plant does not want to lose water.
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chloroplast - Stroma |
the fluid filled interior. Light independent reactions occur in the stroma.
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chloroplast - Thylakoids |
disks made from folds of the inner membrane. Light dependent reactions occur along the thylakoid membranes.
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Write out the summary equation for the process of photosynthesis.
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12 H2O + 6 CO2 + radiant energy -> 6 O2 + C6H12O6 (glucose) + 6 H2O
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light energy
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Light energy is a form of electromagnetic energy that radiates from the sun in rhythmic waves. The distance between two successive waves is the wavelength (colors are determined by specific wavelengths of light).
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Photon
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a packet of radiant (light) energy
Photons vary in wavelength and energy. Photons of short wavelength have more energy than photons of longer wavelength. |
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Chlorophyll A
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is the primary chlorophyll – absorbs blue-violet and red and reflects yellow green. We say it looks “grass green”.
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Chlorophyll B
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picks up what Chlorophyll A misses. It absorbs blue and orange and red. It is thought to look more blue-green.
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Carotenoids
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sometimes called accessory pigments. They also contribute to photosynthesis. Carotenoids absorb blue-violet and/or blue-green and reflect either red, yellow and /or orange. These pigments are found in leaves but are masked by the chlorophylls. They can be seen in leaves in the fall when the chlorophylls break down. Carotenoids are also found in many flowers, fruits and vegetables.
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photosystem
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A photosystem is a cluster of 200 to 300 pigment molecules (chlorophylls a, b and the carotenoids) located in a thylakoid membrane. There are two photosystems – photosystem I (P700) and photosystem II (P680).
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Describe the locations for the light dependent reactions and the light independent reactions.
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Light dependent reactions (cyclic and noncyclic) occur on the thylakoid membranes. The Light independent reactions (the Calvin cycle) occur in the stroma.
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Describe the basic pathway of the Cyclic electron flow (the cyclic light dependent pathway). What are the reactants and the products for this pathway? Describe how the electron is both a reactant and a product.
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Basic pathway:
a. Photons excite photosystem I and it releases an electron to a higher energy level.b. The electron is taken by a primary electron acceptor. c. The primary electron acceptor passes the electron to an ETS which produces ATP. d. The electron is returned to P700 (photosystem I) Reactants – radiant energy and photosystem I (source of electrons) Product – electrons (which are returned to photosystem I) and ATPThis is a cycle because the electron returns to its original location. This pathway originated in ancient bacteria as a way to produce ATP but did not allow for the production of glucose. This pathway can still be used to supplement ATP production. |
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Describe the basic pathway of the Noncyclic Electron flow (the noncyclic light dependent pathways). What are the reactants and the products for this pathway?
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Basicpathway:
a.Photons excite the reaction center ofphotosystem II (P680). b. P680 releases an electron which is picked upby a primary electron acceptor. c. The primary electron acceptor passes theelectron to an ETC which uses the energy in the electron to produce ATP. d. The electron is deposited in photosystem I(P700). e. Photons excite the reaction center P700 whichreleases an electron to a primary electron acceptor. f. The electron is passedto the electron acceptor NADP+. g. NADP+combines with the electron and H+ to produce NADPH. h. Since P680 lost anelectron it must be replaced. Replacement occurs through photolysis. Water is broken down releasing hydrogen ions, electrons and oxygen. Reactants: Photosystems II and I (source of electrons), radiant energy and water. Products and by-product of The NoncyclicPathway: Products: ATP and NADPH Byproduct: oxygen (O2)i |
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Describe the process of photolysis as it is used to replace the electron used in the Noncyclic light dependent pathway.
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Since an electron is lost for photosystem II at the beginning of the noncyclic light dependent pathway, it must be replaced. Notice that photosystem I gains the electron lost by photosystem II and then loses and electron to NADPH.
So photosystem I gains one and loses one (it is even). However, photosystem II loses an electron and needs to get one back or eventually the photosystem will be degraded and destroyed. So the process of photolysis is used to replace the electron lost by photosystem II.In photolysis light is used to break water molecules releasing electrons (which are picked up by photosystem II to replace the ones that are lost) and hydrogen ions and oxygen gas. |
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Describe the basic pathway of the Calvin cycle. Be sure to include how ATP and NADPH are involved. What are the reactants and the products for this pathway?
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a. Six carbon dioxide molecules (from the air) combine with six molecules of ribulose biphosphate (RuBP) in the stroma of the chloroplast. This produces six intermediate molecules (we are not going to learn all the names of the molecules in this cycle).
b. The six intermediates are split into 12 molecules that each contain 3 carbon atoms.c. The 12 intermediate 3 carbon molecules are combined with 12 ATP and 12 NADPH to produce 12 molecules called G3P (this is an abbreviation for the full name – you don’t have to know full names here). d. 10 of the G3P molecules are used to produce 6 RuBP molecules (see how this is a cycle – you have recreated what you started with). e. 2 of the G3P molecules are used to create one molecule of glucose. Reactants: 6 RuBP, 6 carbon dioxide molecules (CO2), 12 ATP and 12 NADPH. Notice that the ATP and NADPH must be produced in the Noncyclic light dependent pathway in order for the Calvin cycle to occur.Products: Glucose and 6 RuBP |
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Describe how ribulose biphosphate (RuBP) is both a reactant and the product.
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RuBP is required for the Calvin cycle to occur and is regenerated by the Calvin cycle. This is what makes this process a cycle. You begin and end with the same molecule.
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Describe the types of organic molecules that can be made from G3P.
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G3P can be used to make more than glucose. Also, glucose can be use to make other carbohydrates. Here is a list of molecules that can be made from G3P and/or glucose.
glucose – can be used for energy starch - made of glucoses. Is stored for later use. sucrose - is a disaccharide made of glucose and fructose. Is a form of sugar that is easily transported around inside the plant. cellulose – is made of glucoses. Is used to make the cell wall. fatty acids - G3P can be used to make fatty acids that are converted into lipids. amino acids - G3P can be used to make amino acids that are used to make proteins. |
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C3 photosynthesis
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use photosynthesis as we have described in the previoussections. These plants tend to live in moderate climates with sufficient rainfall.
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C4 photosynthesis
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These are plants that live in hotter, drier climates. They include sugarcane, some grasses (like crabgrass) and corn. The C4 plantstake in carbon dioxide and fix it into an intermediate molecule so it can be stored. By fixing carbon dioxide, the plants can control the opening and closing of their stomata (pores in the leaves) and reduce water loss.
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CAM photosynthesis
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These are plants that live in very arid environments. They are succulent plants such as pineapple and cacti. The difference for these plants is that they only open their stomata (openings that allow carbon dioxide in, but also allow water to leave) during the night. The nights are cooler and water loss is reduced when the stomata are opened. The carbon dioxide taken in at night and fixed into an intermediate that is stored in large vacuoles in the cells. This stored carbon dioxide can be used in the day when ATP and NADPH are available from the light reactions to turn the Calvin cycle while the plant keeps its stomata closed.
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Cellular Respiration
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a cellular process which requires oxygen to break down glucose, giving off carbon dioxide, water and energy in the form of ATP. Eukaryotic cells produce 36 ATP molecules per glucose. Prokaryotic cells produce 38 ATP
The term aerobic is often used to describe this process because it requires oxygen. |
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Write out the summary equation for cellular respiration
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C6H12O6 + 6O2 + 6H2O -> 6CO2 + 12H2O + 36 – 38 ATP
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What are NAD+ and FAD used for in the process of cellular respiration?
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NAD+ and FAD are coenzymes that can pick up hydrogen ions and electrons. They act as electron carriers. They carry electrons to the ETS (electron transport system or electron transport chain).
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List the four phases of cellular respiration.
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a. glycolysis – takes glucose, splits it and form two pyruvate molecules along with ATP and NADH.
b. preparatory reactions – takes pyruvate and produces acetyl CoA and NADH c. citric acid cycle – takes acetyl CoA and produces ATP, NADH and FADH2 d. electron transport chain – takes the NADH and FADH2 and uses them to produce ATP. |
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mitochondrian: Cristae
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the folds of the inner membrane of the mitochondrian
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mitochondrian: Matrix |
the fluid inside the mitochondrian
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glycolysis
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a. Where does it occur in the cell? In the cytosol
b. What happens in the energy investment step?2 ATP molecules are used to split glucose c. What happens in the energy harvesting step?The two molecules produced by splitting glucose are used to produce 2 pyruvate molecules, 4 ATP molecules and 2 NADH molecules d. For the overall reaction – what are the reactants?The reactants are glucose, 2 ATP, and 2 NAD+ e. For the overall reaction – what are the products?The products are 2 pyruvates, 2 NADH molecules and 4 ATP. However, since you used 2 ATP in the energy investment step, the process of glycolysis actually produces a net total of 2 ATP. |
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preparatory reaction
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a. Where does it occur in the cell?In the matrix of the mitochondrian
b. What are the reactants?2 pyruvates (produced by glycolysis), 2 CoA molecules and 2 NAD+ c. What are the products?2 Acetyl CoA molecules, 2 NADH molecules and 2 carbon dioxide (CO2) molecules. The CO2 molecules are actually byproducts since they must be excreted from the body. |
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Citric Acid cycle
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a. Where does it occur in the cell?In the matrix of the mitochondrian b. What are the reactants?2 Acetyl CoA molecules (produced in the preparatory reaction), 2 oxaloacetate molecules, 6 NAD+ and 2 FAD. c. What are the products?2 oxaloacetate molecules, 6 NADH, 2 FADH2 and 4 CO2 (byproducts) d. What molecule is part of both a reactant and product (this is the molecule that cycles)?Oxaloacetate e. How many times does the cycle turn for each glucose that starts this process? Since there are two acetyl CoA molecules produced, this cycle turns twice. The totals for reactants and products listed above take this into account. |
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electron transport system (or electron transport chain)
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a. Where does it occur in the cell?On the cristae of the mitochondrian
b. What are the reactants?The molecules of the electron transport system (the ETS or ETC – electron transport chain). Requires the 10 NADH and the 2 FADH2 molecules produced in the preceding steps. Also requires oxygen to act as an acceptor for the electrons as they exit the chain. c. What are the products?34 ATP molecules and water |
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How many ATP molecules can be made from each NADH? How many NADH molecules are produced by glycolysis, the preparatory reaction and the citric acid cycle? Total the ATP produced by NADH.
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Each NADH can be used to make 3 ATP molecules. A total of 10 NADH molecules are made in glycolysis (2), the preparatory reaction (2) and the citric acid cycle (6). So the 10 NADH can be used to make a total of 30 ATP molecules.
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How many ATP molecules can be made from each FADH2? How many FADH2 are produced in the citric acid cycle (remember that none are produced in glycolysis and the preparatory reaction)?
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Each FADH2 can be used to make 2 ATP molecules. A total of 2 FADH2 molecules are produced in the citric acid cycle. So FADH2 can be used to make a total of 4 ATP molecules.
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Carbon dioxide is really a byproduct that is produced in some of these reactions. For us it is a waste product and we have to get rid of it (by breathing it out). How many carbon dioxide molecules are produced in the preparatory reaction and the citric acid cycle?
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6 carbon dioxide molecules.
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Give the total ATP produced by one molecule of glucose in a prokaryotic cell and a eukaryotic cell? Why are the numbers different?
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Prokaryotic cells Glycolysis: 2 ATP (net) Preparatory reaction – 0 ATP Citric Acid cycle – 2 ATP ETS – 34 ATP
Total ATP produced per glucose = 38. Now this total is only true for prokaryotic cells. Eukaryotic cellsGlycolysis – 2 ATPPreparatory reaction – 0 ATPCitric acid – 2 ATPETS – 32 ATP Total ATP produced per glucose = 36 In eukaryotic cells, 2 ATP must be used to actively transport the 2NADH from glycolysis into the mitochondrian where they can enter the ETS. So the total ATP production for a eukaryotic cell is 36 ATP. |
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Describe the process of fermentation.
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Fermentation is the breakdown of glucose to produce ATP without oxygen available. This process really includes just glycolysis and then the conversion of pyruvate to either alcohol or some type of acid.
Anaerobic – a term used to describe a process that does not use oxygen. |
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What are the two types of fermentation and what are the products produced by each?
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Alcohol fermentation – is a process used by yeast. Yeast can function anaerobically (without oxygen) or aerobically (with oxygen). In alcohol fermentation, the yeast break the glucose into G3P, then into pyruvate and convert the pyruvate into alcohol. The number of ATP molecules produced per glucose molecule by this process is 2 ATP. So you can see this is not as efficient as aerobic respiration. Think about two things that can be made with yeast – bread and beer. Which takes longer to make? Bread or Beer? Beer takes much longer because the yeast are functioning anaerobically and grow more slowly since they are producing less ATP.
Lactate fermentation – bacterial cells and human muscle cells produce acids when using anaerobic fermentation. Human muscle cells produce the acid lactate (lactic acid). When muscle cells work very hard, they cannot take in enough oxygen to power aerobic respiration. They use fermentation pathways to supplement aerobic respiration. Certain bacteria use fermentation pathways to live and grow and produce acids as well. The total ATP produced per glucose molecule in lactate fermentation is 2 ATP. |
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Can all cells survive using fermentation only?
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Some bacteria (and yeast) can live in completely oxygen free environments. Some bacteria even require completely oxygen free environments. The disadvantage to fermentation lies in the fact that it produces byproducts that are damaging to the organism. If the organism has a way to deal with the toxic byproducts, and it has a low metabolic rate, it can use fermentation to survive without oxygen. We cannot survive without oxygen because our neural tissue (brain) has a very high metabolic rate. Neural tissue cannot survive even short periods without oxygen. And once the brain dies – the rest of the body will die too. So not all cells can survive using fermentation only.
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Catabolic reactions
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break down molecules to produce energy.
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Anabolic reactions
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build molecules and require energy.
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Describe how carbohydrates can be broken down to produce energy.
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All carbohydrates are broken down into monosaccharides.If the monosaccharides is not glucose it will be converted to glucose.For humans the liver converts monosaccharides to glucose.
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Describe how fats can be broken down to produce energy.
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All fats (lipids) are broken down into glycerol and fatty acids. Glycerol is converted into G3P which enter glycolysis. The fatty acids are converted to acetyl CoA and enter the citric acid cycle.
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Describe how proteins can be broken down to produce energy. Include deamination and the production of urea.
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All proteins are broken down into amino acids. The amino acids are deaminated (the amine group is removed). Then the remainder of the molecule enters the citric acid cycle and can be used to produce ATP. The amine group (ammonia) is converted to urea in the liver. Urea is a waste product and must be excreted in urine.
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Summary of energy flow:
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Flow of energy:
• Energy ultimately comes from the sun. • Radiant energy is converted in the chemical energy of glucose. • Glucose is converted into the chemical energy of ATP. • The chemical energy of ATP is used to drive cellular and body processes that require mechanical or radiant energy. • ATP is also used to drive anabolic reactions in the cells. • Since energy cannot be converted from one form to another without the loss of usable energy, these processes also produce radiant energy (heat) which is lost to the environment Sun (radiant energy) → glucose (chemical energy) → ATP (chemical energy) → mechanical energy, electrical energy, anabolic reactions, and radiant energy. |
