4.1 Enzymes Flashcards
Why are enzymes important
Biological catalysts.
Globular proteins that interact with substrate molecules causing them to react much faster.
What’s the role of enzymes in reactions
The chemical reactions for growth are ANABOLIC (building up) reactions and are all catalysed by enzymes.
Energy is constantly needed for majority of living processes and is released from large organic molecules in metabolic pathways consisting of many CATABOLIC (breaking down) reactions which are catalysed by enzymes.
How do enzymes catalyse?
If something is increased, like temp. or pressure, the speed of molecules will increase too so there will be an increase in successful collisions with other molecules -> rate of reaction increases.
Energy needs to be supplied for most reactions to start = ACTIVATION ENERGY.
Enzymes help molecules collide successfully and therefore reduce activation energy.
2 hypotheses:
1. lock and key model - area within tertiary structure of enzyme has a shape complimentary to a specific substrate; area is active site.
When substrate is bound to active site an ENZYME-SUBSTRATE COMPLEX is formed.
- induced-fit hypothesis - active site changes shape slightly to accommodate for the substrate joining onto it. The initial interaction between the enzyme and substrate is weak but these interactions induce changes in the enzyme’s tertiary structure - that can weaken bonds to lower the activation energy.
What are intracellular enzymes
enzymes that act within cells
