Chapter 6 Flashcards
What is metabolism?
Total of all reactions in a cell
Catabolism?
Breaks down! Energy released!
When energy is released, it can be transferred elsewhere in the form of electrons. Is a source of reducing power.
Anabolism?
Builds up! Needs energy to do so.
Needs reducing power. Is a source of electrons. Synthesizes complex organics from simple molecules.
Phototrophs?
Harvest energy and use it to power synthesis of organics from inorganic CO2.
Chemoorganotrophs
Harvest energy from organics
Chemolithotrophs
Harvest energy from inorganics
Exergonic reactions
Energy released. More free energy is present in reactants.
Energonic reactions
Energy is gained. More free energy is present in the products.
ADP + Pi —> ATP
Energy is used. Exergonic. Catabolic rxn.
ATP —> Pi + ADP
Energy released and drives anabolic reactions. Endergonic.
Substrate level phosphorylation
Exergonic. Phosphate comes directly from substrate. Free energy used to phosphorylate ADP to ATP.
Oxidative Phosphorylation
Transfer of electron energy (ETC, proton motive force, ATP synthase). Coupled rxn that is driven by oxidation-reduction reactions.
Photophosphorylation
Light harvested, used to create proton motive force
Electron carriers have oxidative or reducing power?
Reducing power.
True or false: number of steps and speed of reaction is irrelevant because the change in free energy is always the same.
True
Why are numerous steps in metabolism advantageous?
More steps allows cell to have more control over energy release. Also provides variety in points at which it can release energy.
Glucose breaks down to power respiration. Does it lose or gain electrons?
Lose
Oxidation
Lose electrons
Reduction
Gain electrons
True or false - enzymes affect change in free energy
False, because some reactions would occur without enzymes, just very slowly.
Enzymes’ primary function…
to reduce activation energy.
How do enzymes lower Ea?
Binds substrates to active sites, orients substrates so reactive ends of compounds are in close proximity with one another, creates microenvironment (i.e. raise and lower pH to make rxn more favorable), destabilize existing bonds
What does it mean when exergonic rxns are coupled to endergonic?
Energy released from exergonic rxn can be used by endergonic rxn
Factors that affect enzyme activity?
ph, temperature, salt, cofactors (nonprotein)
Cells can turn enzyme activity off and on after transcription and translation. How?
Allosteric regulation. It can be positive or negative. Regulatory molecule binds to the enzyme, but NOT in the active site.
deeThis changes the overall shape of the substrate, and prevents or enhances substrate binding in the active site.
Non-competitive inhibition
Type of negative allosteric regulation. Inhibitor binds to site other than the active site.
Competitive inhibition
Prevents substrate from binding because it competitively inhibits the active site. Competitive inhibitors have similar shapes that fit to the substrate.
ETC, proton motive force, and ATP synthase involve transport of….
electrons
In central catabolism, glycolysis involves oxidation or reduction of glucose?
Oxidation of glucose
Cells need to _______ and use _____ when building new cell material
harvest energy, sources of carbon
Where does the reducing power of central catabolism go?
Respiration or fermentation
