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66 Cards in this Set
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Metabolism |
All the chemical reactions within a living organism |
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Catabolism/Catabolic Reactions |
- generally hydrolytic - breakdown of complex organic molecules into simpler compounds - exergonic |
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Hydrolytic |
Reactions that use water in the breaking down of bonds |
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Exergonic |
Energy is released |
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Types of metabolism |
1. Catabolism 2. Anabolism |
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Anabolism/anabolic reactions |
- Building of complex molecules from simpler ones - endergonic |
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Endergonic |
Energy is required |
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Example of anabolism |
Dehydration synthesis: Reactions that release water |
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Collision Theory |
All molecules are constantly in motion and constantly colliding with each other If there is enough activation energy when these molecules collide, it will lead to a chemical reaction |
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Chemical reaction |
The breaking of chemical bonds and/or the forming of new bonds |
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Enzymes |
Organic catalysts that speed up and direct biochemical reactions without being altered themselves |
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How do enzymes speed up reactions? |
By lowering the energy of activation |
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How much of a difference do enzymes make? |
Enzymes speed up the reaction rate a million times compared to un-catalyzed reactions |
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Substrate |
The specific molecule the enzyme interacts with Enzymes are substrate specific! |
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Most enzymes we study are ____ |
Proteins |
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RNA enzymes |
Ribozymes: Old enzymes that developed early in the evolution of life |
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Describe enzyme action |
1. Substrate bonds with the active site, forming an enzyme-substrate complex 2. The substrate is changed to the product(s) and is released, leaving the enzyme unchanged |
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Active site |
The spot on an enzyme that can form bonds with a substrate |
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Enzyme-substrate complex |
A temporary bond between an enzyme and a substrate during enzyme action |
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Substrate specific |
Enzymes only react with their specific substrate(s) |
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How are enzymes often named? |
After their substrate |
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Examples of enzymes named after their substrate |
1. Lipase (breaks down lipids) 2. Sucrase (breaks down sucrose) 3. Urease (breaks down urea) 4. Protease (breaks down protein) 5. DNase (breaks down DNA) |
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Categories of enzyme classification |
1. Oxidoreductases 2. Transferase 3. Hydrolase 4. Lyase 5. Isomerase 6. Ligases |
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Oxioreductases |
Involved in oxidation and reduction reactions |
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Reduction reactions |
The removing or adding of electrons |
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Transferase |
Transfers functional groups, such as an amino, acetyl, or phosphate group |
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Hydrolase |
Involved in hydrolysis |
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Hydrolysis |
Breaking down molecules in water |
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Lyase |
Removal of groups without hydrolysis |
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Isomerase |
Rearrangement of atoms within a molecule |
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Ligases |
Joining of two molecules, usually coupled with the breakdown of ATP) |
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Components of enzymes with more than just proteins |
1. Apoenzyme 2. Cofactor/Coenzyme |
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Apoenzyme |
The protein part of an enzyme |
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Cofactor/Coenzyme |
Non-protein part of an enzyme. Many are derived from vitamins
Can be inorganic, like an ion, or organic |
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Holoenzyme |
The components of an enzyme put together |
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Examples of coenzymes derived from vitamins |
1. NAD 2. FAD 3. CoA |
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Nicotinamide adenine dinucleotide |
NAD Cornzyme derived from Niacin |
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Niacin |
Vitamin involved in cellular respiration |
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Flavin adenine dinucleotide |
FAD Coenzyme derived from Riboflavin |
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Riboflavin |
A vitamin involved in cellular respiration |
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Coenzyme A |
CoA Coenzyme derived from Panthothenic acid |
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Panthothenic acid |
Vitamin involved in cellular respiration |
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Factors that influence enzyme activity |
1. Denaturation of an active protein 2. Temperature 3. pH 4. Substrate concentration |
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Denaturation |
Loss of shape |
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Most enzymes are ____ |
Proteins |
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How does temperature affect enzyme activity? |
- chemical reaction rates increase a temperature increases - most enzymes have an optimum temperature, beyond which will reduce the rate - eventually, high temperatures will denature most enzymes |
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How does pH affect enzyme activity? |
- Most enzymes have an optimum pH at which their activity is the highest - pH above or below optimum pH will cause a decline in reaction rate - extreme pH will denature enzymes - optimum pH varies |
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How does substrate concentration affect enzyme activity? |
- a higher concentration of substate will increase reaction rate until saturation - after saturation, any further increase will not increase enzyme activity |
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Saturation |
The point at which all active sites are occupied |
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Inhibitors |
Decrease or stop enzyme activity |
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Types of inhibitors |
1. Competitive 2. Non-competitive 3. Reversible 4. Irreversible |
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Competitive inhibitors |
Competes with the substrate for the the active site |
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Non-competitive inhibitors |
Bind to the allosteric site |
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Allosteric site |
The "back door" site When a non-competitive inhibitor binds to this site, the active site shrinks |
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Examples of competitive inhibitors |
1. Penicillin 2. Sulfanilamide |
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Penicillin as an inhibitor |
Competes for the active site of the enzyme involved in the synthesis of the pentaglycine crossbridges |
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Sulfanilamide |
- used to treat bacterial infections before antibiotics (still used today) - competes for the active site on the enzyme that converts PABA (para aminobenzoic acid) into folic acid |
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Examples I'd non-competitive inhibitors |
- cyanide - heavy metals (Hg, Ag) |
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Heavy metals as inhibitors |
Disrupt the disulfide bridges and denature the enzymes |
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Reversible inhibitor |
Structurally very similar to its substrate Binds temporarily to the substrate and does not alter the structure of the enzyme |
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Example of a reversible inhibitor |
Protease inhibitor: Part of HIV therapy Will not permanently have an effect unless one continues to take the medication |
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Irreversible inhibitor |
Binds covalently to the enzyme, permanently altering its structure |
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Covalent bond |
A chemical bond that involves the sharing of electron pairs between atoms |
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Examples of irreversible inhibitors |
1. Penicillin 2. Cyanide |
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Feedback Inhibition |
- Control mechanism that prevents the cell from making too much of any substance - Requires a chain of enzymes working together to make a final end-product - once it reaches a certain concentration, the final end-product acts as a noncompetitive inhibitor to one of the early enzymes in the chain |
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What happens if the concentration of the final product dips during feedback inhibition? |
The end product falls off the enzyme and the process begins again |
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