BIOC/DENT/PHCY 230

LECTURE 1

Overview of MetabolismMetabolism: sum total of reactions

Catabolism:breakdown of polymers and

macromolecules

Anabolism: synthesis of macromolecules and polymers

Energy homeostasis:

Extraction

Storage

Regulation

Hormonal regulation of metabolism

Insulin

Glucagon

Growth Hormone

Cortisol

Adrenaline

Thyroid hormone

PEPTIDE

STEROID

AMINO ACID DERIVED

T3 T4

Thyroid Hormones

Increase metabolic rate

Glycogenolysis, gluconeogenesis & hormone sensitive lipase activity

Synthesised in thyroid gland

Requires protein (thyroglobulin) and iodide

75% of thyroid protein is thyroglobulin

Gland epithelia have Na/I symporter

II

I III

I

IH2O2

CHOLESTEROL

CORTISOL

Glucocorticoid

gluconeogenesis, glycogen synthesis, lipolysis, liver protein and RNA synthesis

cortisol

aldosterone

Glucocorticoid Receptor

Both cortisol and T3 affect transcription

transcortin

cortisol

T4 binding globulin

T3T4

PLASMA TARGET CELL

CORTISOL CR

T3ITBP

THR

Carbohydrate metabolism:

Glucose as a fuel

Tissue usage: all tissues, brain and RBC are obligate users

Dietary forms: mono- and disaccharides, glycogen, starch,

cellulose

Stored as : glycogen

Processed by: glycolysis, CAC, ETC

GLUCOSE FRUCTOSE GALACTOSEMANNOSE

GLYCEROL

Strategy of glycolysis

Splitting reaction

Energy investment

6 carbon

3 carbon

Cost = 2ATP

Energy generation

x2

Yield = 4 ATP

Net = 2 ATP

Fates of pyruvate

pyruvate

+O2

-O2

CAC,ETC fermentation

animals

lactate

yeast

ethanol

O

COO-

CH3

C + NADH + H+ OH

COO-

CH3

CH + NAD+

pyruvate lactate

LDH

oxidised reduced

oxidisedreduced

THE TAKE HOME MESSAGE

Metabolism can be hormonally regulated

Glucose is a major fuel

Glucose can yield energy via glycolysis

The end products of glycolysis can be

metabolised either anaerobically or aerobically