NEET MDS Lessons
Biochemistry
Cori Cycle
The Cori Cycle operates during exercise, when aerobic metabolism in muscle cannot keep up with energy needs.
For a brief burst of ATP utilization, muscle cells utilize ~P stored as phosphocreatine. For more extended exercise, ATP is mainly provided by Glycolysis.
Lactate, produced from pyruvate, passes via the blood to the liver where it is converted to glucose. The glucose may travel back to the muscle to fuel Glycolysis.
The Cori Cycle costs 6 P in liver for every 2P made available in muscle. The net cost is 4 P Although costly in terms of "high energy" bonds, the Cori Cycle allows the organism to accommodate to large fluctuations in energy needs of skeletal muscle between rest and exercise.
Vitamin B6: Pyridoxine, Pyridoxal, Pyridoxamine
Aids in protein metabolism and red blood cell formation. It is also involved in the body’s production of chemicals such as insulin and hemoglobin.
Vitamin B6 Deficiency Deficiency symptoms include skin disorders, dermatitis, cracks at corners of mouth, anemia, kidney stones, and nausea. A vitamin B6 deficiency in infants can cause mental confusion.
Classification of Fatty Acids and Triglycerides
Short-chain: 2-4 carbon atoms
Medium-chain: 6-12 carbon atoms
Long-chain: 14-20 carbon atoms
Very long-chain: >20 carbon atoms
• are usually in esterified form as major components of other lipids
A16-carbon fatty acid, with one cis double bond between carbon atoms 9 and 10 may be represented as 16:1 cisD9.
Double bonds in fatty acids usually have the cis configuration. Most naturally occurring fatty acids have an even number of carbon atoms
Examples of fatty acids
|
18:0 |
stearic acid |
|
18:1 cisD9 |
oleic acid |
|
18:2 cisD9,12 |
linoleic acid |
|
18:3 cisD9,12,15 |
linonenic acid |
|
20:4 cisD5,8,11,14 |
arachidonic acid |
There is free rotation about C-C bonds in the fatty acid hydrocarbon, except where there is a double bond. Each cis double bond causes a kink in the chain,
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 |