enzymes Flashcards
enzymes are
biological catalysts
what are enzymes used in
all metabolic reactions that occur in cells
all chemical reactions that occur in the cells are termed as
metabolic
2 types of metabolic reactions
- anabolic
- catabolic
anabolic reactions refer to
the process of synthesising macromolecules from monomers or simpler molecules
(e.g. sythesis of proteins from amino acids)
catabolic reactions refer to
the process of breaking of macromolecules into monomers or simpler molecules
e.g. catalase breakdowns hydrogen peroxide to oxygen and water molecules
features of enzyemes
- specific in action
- speed up chemical reactions
why is an enzyme specific
- an enzyme has a specific three-dimensional (3-D) shape. It has a depression called the active site
- Only the substrate with a 3-D shape complementary to that of the active site can fit Into the enzyme.
- This results in the formation of an enzyme- substrate complex.
what is the active site
groves or pockets on the surface of an enzyme molecule into which the substrate molecule(s) with the matching shape can fit — just like a lock and key.
which one is the lock
enzyme
which one is the key
substrate
what happens while the substrate is attached to the active site
- a chemical reaction occurs
- The substrate is converted to the products.
general equation of enzymes
e + s → es → e + p
(e = enzyme, s = substrate, p = product)
how do enzymes speed up chemical reaction
lowering the activation energy needed to
start the reaction.
what are enzymes affected by
- temperature
- pH
- substrate concentration
- enzyme concentration
how are enzymes affected by temperature
- An enzyme is less active at low temperatures.
- As the temperature Increases, the rate of enzyme reaction increases.
- Increasing the temperature above the optimum causes a rapid decrease In the rate of enzyme reaction.
why is an enzyme less active at low energy
At low temperature, the kinetic energy of molecules is low. Enzyme and substrate molecules move slowly. The rate of the substrate molecules colliding with the enzyme is very low.
why does the rate of enzyme reaction increase as the temperature increases
- increasing the temperature increases the kinetic energy of molecules.
- The rate of effective collision (i.e. the rate of substrate molecules colliding and fitting into the active site of the enzyme) is increased.
- This increases the rate of enzyme-substrate complex formation.
optimal temperature for human enzymes
40-50°C
why is there a rapid decrease in the rate of enzyme reaction when temperature increases after optimal temperature
the active site of the enzyme molecule begins to lose its original shape and is no longer complementary to the shape of substrate molecules
