Key Structural Diagrams for NEET Biomolecules

Diagram 1 — Sucrose Structure (bond annotation):

Key structural features to note in the Wikimedia image:

• Left ring: alpha-D-glucopyranose unit (6-membered, C1 connected to O of glycosidic bond)
• Right ring: beta-D-fructofuranose unit (5-membered, C2 connected to same O)
• The glycosidic oxygen bridges C1 (Glc) and C2 (Fru) — the anomeric carbons of BOTH sugars
• No free hemiacetal/hemiketal → non-reducing

Diagram 2 — Alpha and Beta glucose (Haworth projection):

Image reference: https://commons.wikimedia.org/wiki/Special:FilePath/$Alpha_D_{glucopyranose}$.svg?width=600

In alpha-D-glucose: C1-OH is below the ring (same side as C6 — the "axial" position). In beta-D-glucose: C1-OH is above the ring (opposite side from C6 — the "equatorial" position).

Diagram 3 — DNA double helix and base pairing:

Image reference: https://commons.wikimedia.org/wiki/Special:FilePath/$DNA_{Structure}$%2BKey%2BLabelled.$pn_{NoBB}$.png?width=600

Key annotations:

• Antiparallel strands (5'→3' top to bottom on left strand; 3'→5' on right)
• Major and minor grooves
• Base pairs (A-T = 2 dashes; G-C = 3 dashes)
• Sugar-phosphate backbone on outside

Diagram 4 — tRNA cloverleaf structure:

Image reference: https://commons.wikimedia.org/wiki/Special:FilePath/TRNA-$Phe_{yeast}_{en}$.svg?width=600

Features to identify:

• Anticodon loop (bottom, reads mRNA)
• D-loop (top left, contains dihydrouridine)
• TψC loop (top right)
• 3'-CCA acceptor stem (top, amino acid attachment)

Diagram 5 — Protein secondary structure:

Alpha-helix image: https://commons.wikimedia.org/wiki/Special:FilePath/Peptide-Figure-Revised.png?width=600