cell metabolism enzymes definition catalysts proteins that speed up chemical reactions by lowering...
TRANSCRIPT
CELL METABOLISM
Enzymes Definition
Catalysts Proteins that speed up chemical reactions by lowering the energy of activation.
LOWERING THE ENERGY OF ACTIVATION
Substrate
ENZYMESCharacteristics
Do not change or get used up.
Is specific to one substrate.
Does not make a reaction happen if it would not normally occur.
ENZYMESStructure
Three-dimensional protein frameworkActive siteCofactors Coenzymes
Organic molecules that become part of the enzyme structure.
Metal ions Inorganic metals that help shape enzyme structure.
ENZYMESMode of Action
Chemical reactionsMust have contact
Fig. 6.6b
ENZYMESMode of Action
Chemical reactionsMust have contactMust have sufficient force
ENZYMESMode of Action
Chemical reactionsMust have contactMust contact with sufficient forceMust have proper orientation
ENZYMESMode of Action
Method Induced Fit
A substrate promotes reactivity by altering the shape of the active site for a more precise fit.
Lock & Key
Induced Fit
PRIMARY PROTEIN STRUCTURE
20 & 30 PROTEIN STRUCTURE
ENZYMESExternal Effects
Temperature Cold Temperatures
Slow reactions down Warm Temperatures
Speed reactions up Hot Temperatures
Denature protein enzymes
ENZYMESExternal Effects
Ph Strong Acids
Denature proteins Strong Bases (Alkaline)
Denature Proteins
ENZYMESOptimum Environment
Resulting effects depend on the strength of the crosslinkages between amino acids.
METABOLISM
DefinitionOrderly sequence of chemical reactions that change substrates into products.
Product 1
Substrate 2
Substrate 1
Product 2
Substrate 3
Product 3
Substrate 4
Final End Product
METABOLISM
PathwaysCatabolic (Degradative)[Exergonic] Breaking down of complex molecules to simpler products with the release of
energy.
Energy
METABOLISM
PathwaysAnabolic (Biosynthetic) [Endergonic] Synthesis of complex molecules with a net input of energy.
Fig. 6.6b
Energy
Fig. 6.3
ANABOLIC
CATABOLIC
ANABOLIC
CATABOLIC
sHEAT
sHEAT
METABOLISMControl
Inhibitors Competitive
Blocking of active site to prevent enzyme action
METABOLISMControl
Inhibitors Noncompetitive Changing of the shape and chemistry of
an enzyme to prevent action.
METABOLISMNoncompetitive
Method Feedback Inhibition
Mechanism by which an end product shuts down the first enzyme of the pathway.Allosteric Enzymes containing an additional binding site for allosteric control.
