Biochemical Metabolism Notes
Subject Overview
Biochemical Metabolism surveys the major metabolic pathways of the human body — carbohydrate metabolism (glycolysis, citric acid cycle, gluconeogenesis, glycogen metabolism), protein metabolism and the urea cycle, lipid digestion and fatty acid metabolism, nucleic acid function, and enzyme structure, kinetics and inhibition — together with the deficiency diseases linked to each pathway. A 4-credit core theory paper.
Subject at a glance
4
Units
26
Topics
4
Credits
4
Infographics
Unit-wise Syllabus
4 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Introduction
- importance and classification
- digestion and absorption
- glycolysis
- citric acid cycle
- gluconeogenesis
- glycogenolysis
- glycogenesis
- disorders of carbohydrate metabolism
- 1Glycolysis
Glucose to 2 pyruvate, in cytoplasm
- 2Link reaction
Pyruvate to acetyl-CoA
- 3Citric acid (TCA) cycle
In mitochondria: NADH, FADH2
- 4Electron transport chain
Most ATP made here
Study guide
This unit covers carbohydrate metabolism: classification, digestion and absorption, glycolysis, the citric acid cycle, gluconeogenesis, glycogenolysis and glycogenesis and disorders such as diabetes mellitus. Draw glycolysis and the citric acid cycle as flow diagrams with the key enzymes and energy yield.
- Introduction
- classification and important properties of proteins
- digestion and absorption
- protein metabolism
- disorders of protein metabolism and the urea cycle
- 1. Carbamoyl phosphate: Made from NH3 + CO2
- 2. Citrulline: With ornithine
- 3. Argininosuccinate: With aspartate
- 4. Arginine: Fumarate released
- 5. Urea released: Ornithine regenerated
Study guide
You study protein metabolism: classification and properties of proteins, digestion and absorption, metabolism, the urea cycle and related disorders. Learn the steps of the urea cycle and why high blood urea is clinically important.
- Lipid classification
- digestion and absorption of fats
- lipoproteins
- fatty acid biosynthesis and oxidation
- nucleic acid introduction and functions
- energy carriers
Chylomicrons
Dietary fat from the gut
Largest, least dense
VLDL
Triglycerides from the liver
Raised in hypertriglyceridaemia
LDL
Cholesterol to tissues
'Bad' cholesterol
HDL
Cholesterol back to the liver
'Good' cholesterol
Study guide
You study lipids and nucleic acids: lipid classification, digestion and absorption, lipoproteins, fatty acid synthesis and oxidation and the functions of nucleic acids and energy carriers. Link lipoproteins such as LDL and HDL to cholesterol tests.
- Introduction
- importance and classification of enzymes
- properties
- mechanism of enzyme action
- factors affecting enzyme action
- enzyme kinetics and inhibitors
Competitive
The active site
Km rises, Vmax unchanged
Non-competitive
Another site
Km unchanged, Vmax falls
Uncompetitive
The enzyme-substrate complex
Both Km and Vmax fall
Study guide
You study enzymes: classification, properties, mechanism of action, factors affecting activity, kinetics and inhibitors. Understand how pH and temperature affect enzymes, since diagnostic enzyme tests depend on it.
Why Biochemical Metabolism Matters
Metabolism explains what blood glucose, urea, cholesterol and enzyme tests actually measure. A good understanding makes clinical biochemistry and disease interpretation much clearer.
How to Prepare for Biochemical Metabolism
- Redraw metabolic pathways from memory with enzymes and energy yield.
- Link each pathway to a disorder and the test used to detect it.
- Revise enzyme kinetics with simple graphs.
Biochemical Metabolism: Frequently Asked Questions
Why are enzymes important in diagnosis?
Changes in the blood levels of certain enzymes indicate damage to specific organs, such as the liver or heart, so they are widely used in diagnosis.
What is glycolysis?
Glycolysis is the pathway that breaks down glucose into pyruvate, releasing a small amount of energy as ATP.