B.1Pooja6.6

Front 1

what do metabolic pathways consist of?

Back 1

metabolic pathways consist of chains and cycles of enzyme catalyzed reactions.

Front 2

The induced fit model

Back 2

-The active site of an enzyme does not fit the substrate precisely. As teh substrate approaches the active site and binds to it, teh shape of the active site changes and fits the substrate.
-The substrate induces the active site to change by weakening the bonds in the substrate during the process, reducing its activation energy.
-Some enzymes have a broad specificity, like proteases. Several different substrates that are similar could bind to the same enzyme.

Front 3

What is the function of enzymes?

Back 3

-Ensymes lower the activation eneggy of the chemical reactions they catalyze.
-the substrate causes the active site to change shape, since the substrate's bonds are weakened and the activation energy is reduced.
Include graphs of exothermic and endothermic reactions.

Front 4

Explain the difference between competitive and non-competitive inhibition, with an example of one of each.

Back 4

competitive inhibition: substarate and inhibitor are chemically similar, and structurally similar.
-The inhibitor binds to the active site of the enzyme, and prevents the substrate from binding. The activity of the enzyme isprevented until the inhibitor dissociates.
Example: inhibition of succinate dehydrogenase by malonate in the Krebs cycle.
Non-competitive inhibition: the substarate and the active site are not similar chemically or structurally. The inhibitor binds toe the enzyme at a different site from the active site, and changes the conformation of the enzyme. The substrate may still be able to bind, but the active site does not catalyze the reaction, or catalyzes it at a slower rate.
Example: metal ions like Copper 2+ and Mercury 2+ and Silver + act as a non competitive in hibitor of many enzymes by binding reversibly to the -SH groups of cysteine, the amino acid that forms disulfide bridges, breaking S-S linkages.

Front 5

The role of allostery in the control of metabolic pathways by end product inhibition.

Back 5

End product inhibition: the product of the last reaction in the pathway inhibits the enzyme that catalyzes the first reaction.
-The inhibited enzyme is allosteric, they have 2 non overlapping binding sites. One active site, and one allosteric site (a form on non competitive inhibition).
-The end product binds to the allosteric site and the structure of the enzyme is altered, decreasing its activity.
-Binding of this inhibitor is reversible, the enzyme will return to its original conformation.
-Metabolites can act as allosteric inhibitors of enzymes earlier ina metabolic pathway and can regulate metabolism according to the requirement of organisms, a form of negative feedback.
Examples: ATP inhibition of posphofructokinase in glycolysis.