Proteins: Where Shape Determines Function
Proteins
1) Building Blocks : __amino acids__
2) There are _20____ amino acids in nature
3) Proteins are built at the __ribosomes_______
(cell structure or organelle)
This is called protein synthesis
4) Proteins are _digested___ (broken down into a usable form) in the_stomach____ and _small intestine___.
Levels of Protein Structure
1) A long chain of amino acids is called a _polypeptide____.
2) The ORDER OF AMINO ACIDS  the __kind____ and _shape___ of the protein.
3) The _shape___ of a protein determines its _function____.
Examples:
1) __
receptor & its hormone
2) ___ receptor & its neurotransmitter
3) ____enzyme & its substrate(s)
4) ____antigens and antibodies (immune system
4) PROTEINS HAVE _SPECIFICITY__
5) Denaturation - _change in the shape of a protein_________
Proteins lose their shape (denature) at high _temperatures_____ or high/low _pH_______.
LOSS OF SHAPE = LOSS OF FUNCTION
Enzymes
Chemical Reactions
Ways to “activate” a reaction :
1) _increase temperature___
2) _add more reactants___
3) _add a catalyst______
H2O2
H2O + O2
H2O2
H2O + O2
What is a CATALYST?
 _ Substance that speeds up a reaction without changing or being used up_______________________
What is an ENZYME?
__
H2O2
H2O + O2
organic catalysts that control the rate (speed) of chemical reactions in living things___
More About Enzymes
● __Enzymes are proteins_____
● __Each enzyme has a specific shape that determines its function _____
This is known as ENZYME SPECIFICITY
● __Enzymes are recycled______
● ___Enzyme names end in -ase__________
___proteins _____ protease _____________
___lipids ______lipase________
_starch (amylose)________amylase____
The Lock & Key Model of Enzyme Action
The Lock & Key Model of Enzyme Action cont…
● The specific molecule that attaches to an enzyme is called a _substrate____.
A substrate is the same thing as a reactant(s).
● The __active site____ is the part of the enzyme that binds to the substrate.
THEY HAVE THE SAME SHAPE!
● The reaction occurs when the enzyme is bound to the substrate in the _enzyme-substrate complex____.
● The __shape____ of the _enzyme___ determines the substrate(s) to which it can bind.
● Enzymes have _specificity_____.
Like other proteins, the shape of the enzyme
determines its function.
Factors Affecting Rate of Enzyme Reactions
1. Temperature
Denaturation - _enzyme changes shape when____
_temperature gets too hot____
2. pH
3. Concentration of Enzyme and Substrate