intermediary metabolism

generates energy from fuel molecules

catabolic or anabolic

catabolism

oxidative degradation

usually exergonic

chem energy released captured in the form of reduced coenzymes (NADH and FADH) that carry energy fwd to form ATP

anabolism

synthetic process

complex biomolecules are assembled from simpler precursors

formation of new covalent bonds

endergonic--input of E (mostly from ATP) drives rxns

exergonic rxns produce ____ (3 molecules)

endergonic rxns consume ___

NADH, NADPH, ATP

NADPH, ATP

What drives reactions?

Free energy ΔG

ΔG=ΔH-TΔS

ΔG, negative=exergonic positive=endergonic

When can catabolic rxns be endergonic and anabolic rxns be exergonic?

Pathways are often linked reactions

therefore, a single step with a pos ΔG may still proceed spontaneously if overall pathway has negative ΔG

unfavorable reactions are often driven by coupling to a favorable reaction

stepwise degradation of nutrient molecules

nutrient macromolecules (proteins, polysaccharides, lipids) are taken up in GI tract and degraded into smaller molecules (aa, monosaccharides, glycerol/fatty acids)

conversion of these molecs to AcCoA-->TCA cycle+oxidative phosphorylation-->ATP

How is energy stored in ATP?

phosphodiester bonds=ENERGY

can be converted to different kinds of energy (heat, mechanical, chemical etc)

Side note: ATP can act as an allosteric inhibitor to some enzymes

Phosphatases and Kinases

Phosphatases dephosphorylate

Kinases phosphorylate

enzyme regulation

Energy molecules (aside from ATP)

GTP--gluconeogenesis, protein synth

UTP--glycogen synth

CTP--lipid synth

AcCoA/succinyl CoA--intermediates in oxidative catabolism

1,3-biphosphoglycerate and phosphoenolpyruvate--intermediates in glycolysis to produce ATP

Where is energy generated?

cytosol: glycolysis (anaerobic)

mitochondria: everything else (aerobic)

Where in the body can glucose, fatty acids, ketone bodies, and proteins be used for E generation?

Glucose: all tissues--glycolysis is anaerobic process

tissues with poor oxygenation/no mitochondria can ONLY utilize glucose--RBC, retina sclera, white skeletal muscle

Fatty acids and amino acid: in tissues with good oxygenation and mitochondria (except brain)--liver, cardiac/red skeletal muscle, etc

Brain: glucose and ketone bodies

4 major energy-generating processes in mitochondria

1) PDH, pyruvate dehydrogenase complex

2)fatty acid beta-oxidation

3) krebs

4)terminal oxidation (Electron transport and ox phosph'n)

inner vs outer mitochondrial membrane

outer: very permeable, simple with few transporters/enzymes

inner: complex, ~80% protein content, semi-permeable, ETC/OP proteins

dicarboxylate transporter

important inner mito memb transport protein

maintains malate/phosphate balance (malate out phosphate in)

important because phosphate is needed to convert ADP to ATP

Adenine nucleotide transporter

important inner mito memb transporter

ADP in ATP out

malate-aspartate and alpha-glycerol phosphate shuttles

transfer reducing equivalents from cytosol to matrix, where they are oxidized in ETC/OP

also reconstruct NAD+ to get back into the cytosol so it can be used in other reactions (glycolysis etc)

irreversible

energy-generating reactions taking place in mitosol

PDH

fatty acid beta-oxidation

Krebs

energy-generating reactions in mitochondrial inner membrane

terminal oxidation