Biology 2.1.4

Enzymes are important because they catalyse reactions, they are globular proteins that interact with substrate molecules causing them to react at much faster rates without the need for harsh environmental conditions. The chemical reacrions required for growth are anabolic reactions-all catalysed by enzymes. Energy is released from large organic molecules in metabolic pathways consisting of many catabolic reactions, which are catalysed by enzymes. Digestion is catalysed by a range of enzymes.

Metabolism: the sum of all the different reactions and reaction pathways happening in a cell or an organism, and it can only happen as a result of the control and order imposed by enzymes. 

Enzymes can only increase rates of reaction up to a point called Vmax, then another factor is limiting. 

Activation energy- the energy needed to be supplied for a reaction to start- enzymes can lower this by helping the molecules to collide successfully. 

Lock and Key Hypothesis- an area within the tertiary struture of an enzyme has a shape that's complementary to the shape of a specific substrate molecule- the active site. Substrate+ enzyme = enzyme substrate complex. The substrate is help in such a way by the enzyme that the atom-groups are close enough to react. The R-groups within the active site of the enzyme will also interact with the substrate, forming temporary bonds that put strain on the bonds within the substrate.

Induced-fit hypothesis- recent evidence suggests that the active site of the enzyme changes shape slightly as the enzyme enters. The initial interaction between the enzyme and substrate is fairly weak, but interactions rapidly induce changes in the enzyme's tertiary structure that strengthen binding, putting strain on the substrate.

Intracellular enzymes- function in the cell that it was produced in, e.g. synthesis of polymers from monomers.

Extracellular enzymes- function outside the cell that it was produced in- enzymes are released by cekks to break down large nutrient molecules into smaller nutrient molecules in the process of digestion. Both single-celled and multicellular organisms rely on extracellular enzymes to make us of polymers for nutrition. single-celled organisms (e.g. yeast) release enzymes into their immediate environment to break down larger molecules and then the smaller molecules produced (e.g. A.A) are absorbed by the cell. 

Amylase- starch is the substrate and the…