NEET MDS Lessons
Biochemistry
| Enzyme | Clinical Use | Indicates |
|---|---|---|
| Amylase | Acute pancreatitis | Rises quickly, short half-life |
| Lipase | More specific for pancreatic damage | Stays elevated longer than amylase |
Lipase is preferred for diagnosing pancreatitis due to higher specificity.
FLUORIDE
The safe limit of fluorine is about 1PPM in water. But excess of fluoride causes Flourosis
Flourosis is more dangerous than caries. When Fluoride content is more than 2 PPM, it will cause chronic intestinal upset, gastroenteritis, loss of weight, osteosclerosis, stratification and discoloration of teeth
These are normally non-essential but become essential during stress, illness, or in infants.
| Conditionally Essential | When Needed |
|---|---|
| Arginine | Growth, trauma, immune stress |
| Cysteine | Liver disease, oxidative stress |
| Glutamine | Critical illness, burns |
| Tyrosine | PKU (phenylketonuria) patients |
| Proline, Glycine | Wound healing, collagen synthesis |
Vitamin B12: Cobalamin
Vitamin B12, also known as cobalamin, aids in the building of genetic material, production of normal red blood cells, and maintenance of the nervous system.
RDA The Recommended Dietary Allowance (RDA) for vitamin B12 is 2.4 mcg/day for adult males and females
Vitamin B12 Deficiency
Vitamin B12 deficiency most commonly affects strict vegetarians (those who eat no animal products), infants of vegan mothers, and the elderly. Symptoms of deficiency include anemia, fatigue, neurological disorders, and degeneration of nerves resulting in numbness and tingling.
Polar (Uncharged)
| Amino Acid | Key Feature |
|---|---|
| Serine (S) | Hydroxyl group |
| Threonine (T) | Hydroxyl group |
| Asparagine (N) | Amide group |
| Glutamine (Q) | Amide group |
| Tyrosine (Y) | Phenol group |
| Cysteine (C) | Thiol group |
Mnemonic: "Santa’s Team Never Quit Trying Cookies" (S, T, N, Q, T, C)
Non-Polar (Hydrophobic)
| Amino Acid | Key Feature |
|---|---|
| Glycine (G) | Smallest side chain |
| Alanine (A) | Methyl group |
| Valine (V) | Branched chain |
| Leucine (L) | Branched chain |
| Isoleucine (I) | Branched chain |
| Methionine (M) | Sulfur-containing |
| Proline (P) | Cyclic structure |
| Phenylalanine (F) | Aromatic ring |
| Tryptophan (W) | Indole ring |
Mnemonic: "Grandma Always Visits London In May For Perfect Weather" (G, A, V, L, I, M, F, P, W)
Enzyme assays measure the activity or concentration of specific enzymes in blood or tissue samples. Elevated or reduced levels often indicate organ dysfunction or cellular damage.
Enzyme Groups & Their Clinical Significance
| Enzyme Group | Function | Clinical Relevance |
|---|---|---|
| Oxidoreductases | Catalyze oxidation-reduction reactions | Liver, cardiac, and muscle injury markers |
| Transferases | Transfer functional groups between molecules | Liver and muscle enzymes (e.g., AST, ALT) |
| Hydrolases | Break chemical bonds using water | Pancreatic enzymes (e.g., amylase, lipase) |
| Lyases | Break bonds without hydrolysis or oxidation | Less commonly used in diagnostics |
| Isomerases | Rearrange molecular structures | Rarely used clinically |
| Ligases | Join molecules using ATP | Mostly research-based, not routine diagnostics |
Titration of a weak acid with a strong base
• A weak acid is mostly in its conjugate acid form
• When strong base is added, it removes protons from the solution, more and more acid is in the conjugate base form, and the pH increases
• When the moles of base added equals half the total moles of acid, the weak acid and its conjugate base are in equal amounts. The ratio of CB / WA = 1 and according to the HH equation, pH = pKa + log(1) or pH = pKa.
• If more base is added, the conjugate base form becomes greater till the equivalance point when all of the acid is in the conjugate base form.