BCH 4033- ch.15 metabolism: basic concepts and themes

exam 3 content

where do cells extract energy from and what do they use it for?

their environment

used to convert simple molecules into cellular components

where does energy transduction take place through?

metabolism

• highly integrated network of chemical reactions

what can metabolism be subdivided into?

catabolism and anabolism

• extract energy from fuels and require energy

when can a spontaneous reaction occur?

if the change in free energy (delta G) is negative

what is thermodynamically unfavorable reaction driven by?

by a thermodynamically favorable one, usually hydrolysis of ATP

what is the energy from catabolism captured as?

adenosine triphosphate (ATP)

what is ATP hydrolysis?

an exergonic process

energy released and used to power cellular processes

• ex.) motion, active transport, biosynthesis

what is ATP?

an energy-rich molecule

contains 2 kinetically stable but thermodynamically unstable phosphoanhydride linkages

what is ATP formation coupled to?

the oxidation of chemicals

• directly or through formation of ioin gradients in chemotrophs

what are chemotrophs?

organisms that get energy by the oxidation of chemicals

organochemotroph → organic chemical source

lithotroph → inorganic chemical source

how can ion gradients for ATP be generated?

using phototrophic organisms, including photosynthetic organisms → use light to generate gradient

what are phototrophs?

organisms that can meet its energy needs by converting light energy into chemical energy

what are the 3 stages of extraction of energy from food by aerobic organisms?

1. large molecules are catabolized into smaller ones (ex. AAs, sugars, fatty acids)

2. the small molecules are degraded to a few simple units (ex. acetyl CoA

   1. the citric acid cycle and oxidative phosphorylation generate ATP as electrons flow to O2 and fuels are completely oxidized to CO2

what is the function of the recurring activated carriers in metabolism?

to transfer activated groups in many metabolic pathways

what are the recurring activated carriers in metabolism?

ATP, NADH, acetyl CoA

derived from vitamins

what are vitamins?

small organic molecules required in the diets of many higher organisms

what activated metabolism carriers are derived from

what is NADPH?

a metabolism carrier that carries 2 electrons at a high potential

provides reducing power for reductive biosynthesis of cells components

how is metabolism regulated?

the amounts of enzymes are altered

the catalytic activities of many enzymes are regulated by allosteric interactions and controlled by covalent modification

availability of many substrates is limited

what does ATP inhibit?

ATP-generating pathways and stimulates ATP-utilizing pathways

AMP has opposite effect