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Carbohydrates & Biomolecules formula sheet

Every formula in the Carbohydrates & Biomolecules chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 21 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that formula, and "last" is the latest year one appeared. ★ marks formulas asked 8 or more times.

Carbohydrates: monosaccharides

Classification
4× asked, last 2026
mono: no hydrolysis;oligo: 2–10 unitspoly: many units\begin{aligned}&\text{mono: no hydrolysis};\quad \text{oligo: 2–10 units}\\&\text{poly: many units}\end{aligned}
Polyhydroxy aldehydes or ketones, or what hydrolyses to them. Sucrose, lactose give unlike units.
Glucose and fructose
9× asked, last 2026
glucose (aldohexose): OHC−(CHOH)X4−CHX2OHfructose (ketohexose): HOCHX2−CO−(CHOH)X3−CHX2OHopen-chain stereoisomers: 24=16,23=8\begin{aligned}&\text{glucose (aldohexose): }\ce{OHC-(CHOH)4-CH2OH}\\&\text{fructose (ketohexose): }\ce{HOCH2-CO-(CHOH)3-CH2OH}\\&\text{open-chain stereoisomers: }2^4=16,\quad 2^3=8\end{aligned}
D/L: OH on the lowest chiral C right/left (Fischer), not the sign of rotation: D-(−)-fructose. D-glucose C2–C5: R, S, R, R.
Open-chain evidence
6× asked, last 2026
glucose→HI, Δn-hexane,→NHX2OHoxime→BrX2 watergluconic acid,→HNOX3saccharic acid→(CHX3CO)X2Opentaacetate\begin{aligned}&\text{glucose}\xrightarrow{\ce{HI},\ \Delta}n\text{-hexane},\qquad \xrightarrow{\ce{NH2OH}}\text{oxime}\\&\xrightarrow{\ce{Br2}\text{ water}}\text{gluconic acid},\qquad \xrightarrow{\ce{HNO3}}\text{saccharic acid}\\&\xrightarrow{\ce{(CH3CO)2O}}\text{pentaacetate}\end{aligned}
Straight C6 chain; a C=O that is CHO (BrX2\ce{Br2} water oxidises only CHO); five OH. HNOX3\ce{HNO3} also oxidises CHX2OH\ce{CH2OH}.
What the open chain cannot explain
4× asked, last 2026
no Schiff, 2,4-DNP or NaHSOX3 productpentaacetate: no oxime\begin{aligned}&\text{no Schiff, 2,4-DNP or }\ce{NaHSO3}\text{ product}\\&\text{pentaacetate: no oxime}\end{aligned}
Only a little open chain is present, so glucose still reduces Tollens and forms an oxime.
Anomers and mutarotation
7× asked, last 2026
α (+112∘)⇌open chain⇌β (+19∘)equilibrium mixture: +52.5∘\begin{aligned}&\alpha\ (+112^\circ)\rightleftharpoons\text{open chain}\rightleftharpoons\beta\ (+19^\circ)\\&\text{equilibrium mixture: }+52.5^\circ\end{aligned}
C5–OH closes on C1: pyranose. Anomers differ at C1 only (glucose, galactose differ at C4: epimers). α: OH trans to CHX2OH\ce{CH2OH}.
Fructose
5× asked, last 2026
C2 ketone; C5–OH closes on C2⇒furanose\text{C2 ketone; C5–OH closes on C2}\Rightarrow\text{furanose}
−92.4°. In sucrose: β-D-fructofuranose. Reduces Tollens, Fehling (base forms an enediol).

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15 more formulas in 5 topics

Disaccharides and polysaccharides; Amino acids; Peptides, proteins and enzymes; Vitamins; and Nucleic acids. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Disaccharides and polysaccharides

  • Reducing sugars8×
  • Sucrose and invert sugar10×
  • Maltose and lactose13×
  • Polysaccharides9×

Amino acids

  • α-Amino acids10×
  • One-letter codes13×
  • Zwitterion and chirality6×

Peptides, proteins and enzymes

  • Counting peptides17×
  • Levels of structure7×
  • Fibrous, globular, denaturation8×
  • Enzymes7×

Vitamins

  • Solubility5×
  • Deficiency diseases8×

Nucleic acids

  • Nucleotides, DNA, RNA8×
  • Base pairing6×

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