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chemistry
Enzymes
| Question | Answer |
|---|---|
| enzymes can catalyze a biochemical reaction without? | altering the equilibrium point of the reaction,being consumed,changing its composition |
| Active site | cavity where substrate is acted on |
| substrate | substance enzymes act upon |
| allosteric site | site that bind regulator |
| Iso enzyme | different forms of enzymes |
| cofactor | nonprotein enzyme activator |
| prosthetic group | enzyme/coenzyme complex |
| Nomenclature | numerical code, last number specific to each enzyme |
| activation energy | the energy necessary to begin the catalytic mechanism |
| how is activation energy achieved? | increased body temp, enzymes lower activation energy needed |
| name 4 catalytic mechanisms | absolute specificity, group specificity, bond specificity, stereosometric specificity |
| absolute specificity | enzyme combines with only one substrate and only one reaction occurs |
| group specificity | enzyme combines with all substrate in a chemical group |
| bond specificity | enzymes that are specific for certain chemical bonds |
| stereoisometric specificity | enzymes that predominantly combine with one optical isomer of a certain compound |
| factors that influence reactions | substrate concentration,enzyme concentration, pH, temperature, cofactors, inhibitors |
| at low concentrations reaction rate is directly proportional to the concentration of substrate | First order kinetics |
| substrate concentration is high enough to saturate all the available enzyme | zero order kinetics |
| what is the reaction rates for zero order kinetics | reaches plateau, becomes constant, independent of substrate concentration, only dependent on concentration of enzyme |
| Michaelic-Menton Constant(Km) | the constant from a specific enzyme reaction vs. the substrate concentration. |
| determined by plotting the rate of reaction of an enzyme catalysed reaction vs. the substrate concentration | Michaelic-Menten Constant (Km) |
| How does the enzyme concentration influence reactions | rate of catalyzed reaction |
| How does the pH influence the reaction? | denaturation or changes |
| How does the temperature influence the rate of reaction? | denaturation, rate |
| how does the cofactors influence the reaction? | necessary for reaction, excess-inhibit reaction |
| How does the inhibitors influence the reaction? | a substance that bind to particular enymes, resluting in a decrease in reaction velocity, 3 types |
| competitive inhibitors | bind to the active site and compete with substrate for the active site, may damage enzyme, |
| How may competitive inhibitors be overcome? | increase in substrate, but results in a higher Km, because increased substrate is required to react the max.catalysis |
| Non competitive inhibitors | bind the enzyme on a site other than active site, may be reversible or irreversible if the inhibitor destroys part of enzyme.cannot be be overcome by substrate |
| Uncompetitive Inhibitors | the inhibitor binds to the ES complex, the more ES compexes the more inhibition. |
| Increasing substrate will not overcome the problem but actually increase the problem | Uncompetitive Inhibitors |
| Enzymes are in very small quantities, so how are they measured? | measure activity to quantify enzyme concentrations |
| what are the 3 phases of reactions | lag, linear, substrate depletion |
| Lag phase | initial mixing of specimen and reagent, little change noted |
| Linear phase | zero order kinetic prevails, absorbance change becomes constant over time |
| Substrate depletion | dependant on the amount and activity of the enzyme present in the specimen |
| 1U | the amoount of enzyme tht will catalyze the reaction of 1 microole of substrate per minute under specified conditions of temp.,pH, substrate and activators |
| what does photometric measure? | increase product conc, decreased substrate conc.,decreased coenzyme conc.,increase conc. of altered coenzyme. |
| what does Mass Assay measure? | protein mass=enzyme concentration, |
| What is Mass Assay used for? | Isoenzyme |
| What has the Mass Assay replace? | Electrophoresis |
Created by:
joanndibattisto
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