METABOLISM

Catabolism

Breakdown; releases energy.

Anabolism

Build-up; consumes energy.

Amphibolic Pathway

acts at the crossroads of anabolic and catabolic metabolism;

TCA cycle is the source example.

ATP

Cellular energy currency;

energy is stored in ATP bonds and released on hydrolysis.

Substrate-level phosphorylation:

direct transfer of high-energy phosphate to ADP.

 Oxidative phosphorylation:

ATP synthesis using energy from electron transport in mitochondria.

Fed state

Glycolysis

Glycogenesis

Lipogenesis

Insulin predominates

Fasted state

Glycogenolysis

Gluconeogenesis

Lipolysis

Glucagon predominates

Embden-Meyerhof pathway:

main pathway for glucose oxidation in human tissues; occurs in cytoplasm.

10 enzyme-catalyzed steps yields?

2 pyruvate.

Cytoplasm

glycolysis location

Steps

GLYCOLYSIS

10 total

Phase 1

GLYCOLYSIS

Steps 1-5 = energy investment

Phase 2

GLYCOLYSIS

Steps 6-10 = energy payoff

Irreversible steps

GLYCOLYSIS

1, 3, 10

Rate-limiting step

GLYCOLYSIS

Step 3

Source ATP values

GLYCOLYSIS

2 ATP without NADH;

7 ATP with NADH

PYRUVATE FATES

 Aerobic context ->

 Anaerobic context ->

acetyl-CoA -> TCA cycle.

fermentation pathway in the source.

GLUCONEOGENESIS

 Makes new glucose from pyruvate, amino acids, glycerol, or lactate.

 Requires biotin

liver, kidneys, intestinal epithelium.

Lactate -> glucose =

alanine -> glucose =

Cori cycle;

Cahill/alanine cycle.

GLYCOGENOLYSIS

 Fasted state; stimulated by glucagon; increases blood glucose.

 Glycogen phosphorylase breaks alpha-1,4 bonds.

type 0

Glycogen synthase

N/A

type I-a

Glucose-6-phosphatase

Von Gierke

type I-b

Glucose-6-translocase

type II

Lysosomal alpha-glucosidase

Pompe - acid maltase deficiency

type IV

Branching enzyme

Andersen’s – amylopectinosis

type 5

Muscle glycogen phosphorylase

Mc Ardle’s

type 6

Hepatic glycogen phosphorylase

Hers’

type 7

Phosphofructokinase

Tarui’s

G6PD Deficiency –

causes hemolytic anemia due to decrease NADPH from PPP → decreased active GSH → increase oxidative stress → increase hemolysis

PENTOSE PHOSPHATE PATHWAY (HMP SHUNT)

generates NADPH and provides ribose-5-phosphate for nucleotide synthesis.

Malate-aspartate .

Transfers cytosolic reducing equivalents into mitochondria efficiently

Glycerol phosphate

Transfers cytosolic reducing equivalents through FAD-linked pathway.