1. Urine Chemistry Table

• DKA: Glucose spills into urine (glucosuria, which is a reducing sugar), and ketones are high due to uncontrolled fat breakdown. No significant protein loss.
• Starvation: No excess glucose to spill, so urine glucose is negative. But ketones are positive because the body burns fat for energy, producing ketone bodies.
• MCHAD Deficiency (Medium-Chain 3-hydroxyacyl-CoA Dehydrogenase deficiency): A fatty acid oxidation disorder. Ketones are present due to impaired fat metabolism, but no glucosuria or proteinuria.

2. Non-Reducing Sugars: Sucrose & Trehalose

• Most sugars (glucose, fructose, galactose, lactose, maltose) are reducing sugars - they have a free aldehyde/ketone group that can reduce Cu²⁺ in Benedict's test.
• Sucrose and Trehalose are non-reducing because their anomeric carbons are both involved in the glycosidic bond, leaving no free reducing group. This is what the handwritten "REST" annotation points to - the REST of the sugars reduce, but these two don't.

3. Glycolysis Effects - Key Concepts

Pasteur Effect

• Inhibition of glycolysis by O₂
• When oxygen is available, aerobic respiration is preferred over glycolysis (fermentation). O₂ "inhibits" anaerobic glycolysis because it is far more efficient (36-38 ATP vs 2 ATP).

Crabtree Effect

• Lactic acidosis if glucose concentration is increased in the presence of O₂
• Seen in yeast and some tumor cells. When glucose is very high, glycolysis is so fast that it outpaces the mitochondria, producing lactate even in the presence of oxygen. The opposite of the Pasteur effect.

Warburg Effect

• Aerobic glycolysis
• Cancer cells preferentially use glycolysis even when O₂ is available, producing lactate. This is the metabolic hallmark of cancer. Warburg won the Nobel Prize for discovering this.

Summary of the trio: Pasteur = O₂ inhibits glycolysis. Crabtree = high glucose overrides O₂ in yeast. Warburg = cancer cells do glycolysis even with O₂.

4. Van Der Bergh's Reaction

• A test to distinguish conjugated (direct) vs unconjugated (indirect) bilirubin.
• Direct positive Van Der Bergh's reaction means conjugated bilirubin is elevated → points to obstructive jaundice (bile cannot flow out, so conjugated bilirubin backs up into blood).

5. Lipotropic Factors and Fatty Liver

• Lipotropic factors prevent fat accumulation in the liver. They include: Choline, Lecithin, Methionine, Vitamin B12, and Folate.
• Arginine is NOT lipotropic - it does not prevent fatty liver.
• These lipotropic factors are useful in treating fatty liver because they aid phospholipid synthesis and fat export from the liver.

6. Fish Odour Syndrome (Trimethylaminuria)

• Choline is avoided in this condition.
• Fish odour syndrome occurs when the body cannot metabolize trimethylamine (TMA) - a breakdown product of choline - producing a fishy body odour.
• Since choline is a precursor to TMA, it must be restricted.

7. Dietary Fibre in Diabetes (DM)

• Gums, Pectin, and Mucilage are soluble dietary fibres.
• They are useful in Diabetes Mellitus because they slow glucose absorption from the gut, blunting post-meal blood sugar spikes.

8. Isoelectric Point & Buffering (Bottom Right)

• Isoelectric point (pI): The pH at which a protein carries zero net charge.
  • At pI, proteins have maximum precipitation (least soluble) because there is no electrostatic repulsion between molecules.
• pK (pKa): The pH at which a titratable group is half-ionized - this is where maximum buffering action occurs.
• The titration curve shown has multiple inflection points. Each inflection = one ionizable group (side chain). The number of curves = number of ionizable side chains in that amino acid.