Ch.5 Microbial Metabolism Flashcards
Metabolism
the buildup and breakdown of nutrients within a cell
metabolism chemical reactions provide
energy and create substances that sustain life
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
sequences of enzymatically catalyzed chemical reactions in a cell
metabolic pathways are determined by
enzymes
enzymes are
encoded genes
Collision theory
states that chemical reactions occur when atoms, ions, and molecules collide
Activation energy
the collision energy required for a chemical reaction to occur
Reaction rate
frequency of collisions containing enough energy to bring about a reaction
reaction rate can be increased by
enzymes or by increasing temp., pressure, or concentration
catalysts
speed up chemical reactions without being altered
enzymes
are biological catalysts
enzyme-susbstrate complex
substrate the enzyme’s active site
products
released from the enzyme when substrate is transformed and rearranged
Turnover number
the number of substrate molecules an enzyme converts to a product per second
Oxidoreductase
oxidation-reduction reactions
transferase
transfer functional groups
hydrolase
hydrolisis
lyase
removal of atoms without hydrolysis
isomerase
rearrangement of atoms
ligase
joining of molecules; uses ATP
Apoenzyme
protein portion (inactive when alone)
Cofactor
nonprotein component
coenzyme
organic cofactor
holoenzyme
apoenzyme plus cofactor (whole, active enzyme form)
Factors influencing enzyme activity
-temp.
-pH
-substrate conc.
-inhibitors
high temp. and extreme pH does what?
denature proteins
Saturation
-when the conc. of substrate is high.
-enzyme catalyzes at its maximum rate
Competitive inhibitors
fill the active site of an enzyme and compete with the substance
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 binding to substrates and acting upon them
-not used up in the reaction
-frequently used in cells to cut and splice RNA
-also involved in protein synthesis in ribosomes
Oxidation
removal of electrons
reduction
gain of electrons
redox reaction
an oxidation reaction paired with a reduction reaction
dehydrogenations
biological oxidations
ATP is generated by the
phosphorylation of ADP with the input of energy
ATP is generated when
high-energy PO4- is added to ADP
Chemiosmosis
a mechanism that uses a proton gradient across a cytoplasmic membrane to generate ATP