[SEC 3] CHAPTER 4 - enzymes Flashcards
define biological catalysts
Alter or speed up a chemical reaction without itself being chemically changed at the end of the reaction
What are the 2 types of reactions in an organism with enzymes?
- Anabolic reactions
- Catabolic reactions
what is metabolism
the sum total of all chemical reactions
anabolism + catabolism = metabolism
what is anabolic reaction and state an example
synthesis (build up) of complex molecules from simpler ones
example: synthesis or proteins from amino acids in cytoplasm of cell
what is catabolic reaction and state an example
Breaking down of large, complex molecules into simpler ones
example:
1) Digestion of starch to maltose and then to glucose (soluble & diffusible across partially permeable membrane)
2) Cellular respiration: A series of chemical reactions involving an enzyme for each reaction to break down of glucose to release energy, carbon dioxide and water.
define activation energy
the energy needed to start a chemical reaction
name the 5 characteristics of enzymes
enzymes:
1. speed up chemical reactions
2. are required in minute amounts
3. are specific in action
4. are affected by temperature and pH
what is the lock and key in the ‘lock-and-key’ hypothesis?
lock: enzyme
key: substrate
name the steps for the ‘lock-and-key’ hypothesis
- the substrate enters the active site of the enzyme
- enzyme changes shape slightly as enzyme and substrate binds, forming an enzyme-substrate complex
- enzyme-substrate complex becomes an enzyme-products complex
- products leave the active site of the enzyme
what is an active site?
a portion of the enzyme that attaches the substrate by means of weak chemical bonds
what is the type of reaction during ‘lock-and-key’
catabolism
how does chemical reactions occur?
- enzyme and substrate molecules collide in the correct orientation
- substrate gets attached at the active site
- chemical reaction occurs
- products formed and leave the current site
- enzyme remains unchanged and is free to react again
define denaturation
the change in the three-dimensional structure of an enzyme, caused by heat or chemicals such as acids or alkalis
what happens during denaturation?
- enzymes loses its 3D configuration
- active site becomes altered
- substrate cannot fit into the active site of the enzyme
- no reaction occurs
-irreversible process
how does pH level affect an enzyme?
extreme changes in the acidity or alkalinity of the solution will denature the enzyme
