Chp 5 Flashcards
Metabolism is the
buildup and breakdown of nutrients within a cell
These chemical reactions provide energy and create substances that sustain life
Metabolism
microbial metabolism can cause
disease and food spoilage, many pathways are beneficial rather than pathogenic
Catabolism
breaks down complex molecules; provides energy and building blocks for anabolism; exergonic
Anabolism
uses energy and building blocks to build complex molecules; endergonic
Metabolic pathways are
sequences of enzymatically catalyzed chemical reactions in a cell
Metabolic pathways are determined by
enzymes
Enzymes are encoded by
genes
The collision theory states
that chemical reactions occur when atoms, ions, and molecules collide
Activation energy
is the collision energy required for a chemical reaction to occur
Reaction rate
is the frequency of collisions containing enough energy to bring about a reaction
Reaction rate can be increased by
enzymes or by increasing temperature, pressure, or concentration
Catalysts
speed up chemical reactions without being altered
Enzymes are
biological catalysts
Enzymes act on a
specific substrate and lower the activation energy
Substrate contacts the enzyme’s active site to form an
enzyme-substrate complex
Substrate is transformed and rearranged into
products, which are released from the enzyme
Enzyme is unchanged and can react with other
substrates
Enzymes have specificity for
particular substrates
Turnover number is the
number of substrate molecules an enzyme converts to a product per second
Generally 1 to 10,000
Names of enzymes usually end in
ase
Naming enzymes
1) Oxidoreductase: oxidation-reduction reactions
2) Transferase: transfer functional groups
3) Hydrolase:
hydrolysis
4) Lyase: removal of atoms without hydrolysis
5) Isomerase: rearrangement of atoms
6) Ligase: joining of molecules; uses ATP
Enzyme Components
1) Apoenzyme: protein portion
2) Cofactor: nonprotein component
- –Coenzyme: organic cofactor
3) Holoenzyme: apoenzyme plus cofactor
Enzyme Components Assist
enzymes; electron carriers
example:
- Nicotinamide adenine dinucleotide (NAD+)
- Nicotinamide adenine dinucleotide phosphate (NADP+)
- Flavin adenine dinucleotide (FAD)
- Coenzyme A
Factors Influencing Enzyme Activity
1) Temperature
2) pH
3) Substrate concentration
4) Inhibitors
High temperature and extreme pH do what to enzyme activity
denature proteins
what happens to enzymes if the concentration of substrate is high
(saturation), the enzyme catalyzes at its maximum rate
increasing temperature does what to enzymatic activity
The enzymatic activity (rate of reaction catalyzed by the enzyme) increases with increasing temperature until the enzyme, a protein, is denatured by heat and inactivated. At this point, the reaction rate falls steeply.
Competitive inhibitors
fill the active site of an enzyme and compete with the substrate
Noncompetitive inhibitors
interact with another part of the enzyme (allosteric site) rather than the active site in a process called allosteric inhibition
Feedback Inhibition
End-product of a reaction allosterically inhibits enzymes from earlier in the pathway
Ribozymes
RNA that function as catalysts by cutting and splicing RNA
Oxidation:
removal of electrons