Exam 3 Metabolism 11/7 Flashcards
What are the different nutritional types of organisms in terms of carbon, energy, and electron acquisition?
All organisms need nutrients to produce to live, grow, and divide.
The process of incorporating nutrients into cellular parts is called assimilation.
Acquisition of Energy
Phototrophs – acquire energy from light energy to create ATP.
Chemotrophs – acquire energy from organic or inorganic compounds from the environment.
Acquisition of Electrons
Organotrophs – acquire electrons from organic molecules.
Lithotrophs – remove electrons from inorganic molecules.
Acquisition of Carbon
Heterotrophs – Assimilate carbon from pre-existing organic molecules.
Autotrophs – assimilate carbon from inorganic sources like CO2.
What are the basic principles of catabolism and energy that control metabolism?
Catabolism: Breaking down larger molecules to obtain energy and smaller precursors
Anabolism: Use of smaller precursor molecules and energy from catabolism to build macromolecular cell components
Metabolism is mediated by enzymes.
Enzymes catalyze biochemical reactions.
An enzyme’s active site binds specific substrates and helps to convert them to products.
Energy
Products of a chemical reaction must have a lower free energy than the reactants.
Energy released is known as Gibbs free energy (G).
Change in free energy in a reaction = ΔG°’
An energy-yielding reaction is exergonic (with a negative ΔG°’).
An energy-absorbing reaction is endergonic (with a positive ΔG°’).
Endergonic reactions in cells are coupled with exergonic reactions to drive them to completion.
The rate at which the reaction will occur is determined by its activation energy (EA).
Enzymes and activation energy
Enzymes jump-start reactions by lowering their EA, placing substrates in a more optimal arrangement.
Structure and Classification of Enzymes
Enzymes-catalysts
some enzymes are composed solely of one or more polypeptides
some enzymes are composed of one or more polypeptides and non-protein components
Cofactors=
coenzymes/prosthetic groups
Important Coenzymes
NAD+
NADP+
FAD
Coenzyme A
Factors Influencing Enzyme Activity
Enzymes can be denatured by temperature and pH
Effect of [substrate]Michaelis-Menton Kinetics
rate increases as [substrate] increases
no further increase occurs after all enzyme molecules are saturated with substrate
Enzyme Inhibition
competitive inhibitor
noncompetitive inhibitor
competitive inhibitor
directly competes with binding of substrate to active site
