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🧪 Chemistry  ·  Biomolecules  ·  NEET & JEE

Which lipoprotein carries cholesterol from tissues back to the liver?

Answer: HDL.

  • A HDL
  • B LDL
  • C VLDL
  • D Chylomicron

Correct answer: A. HDL

Explanation: HDL (high-density lipoprotein) is the 'good' cholesterol carrier that transports cholesterol to the liver for processing.

Peptide Bond Formation (Condensation)H₂N-CH(R₁)-C(=O)OHAmino acid 1+HNH-CH(R₂)-COOHAmino acid 2H₂N-CH(R₁)-CO-NH-CH(R₂)-COOHDipeptide+ H₂OThe -OH (from acid 1) and -H (from amine 2) combine to release water, forming the -CO-NH- peptide bond

Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.

Concept context

The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.

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