09Class 11 Biology

Biomolecules short notes

Short notes on proteins, carbohydrates, lipids, nucleic acids and enzymes. These ideas come back in respiration, photosynthesis and genetics.

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Basic types

Amino acids have an amino group, a carboxyl group, hydrogen and an R group on the α-carbon.
Micromolecules are under 1000 Da, and macromolecules are larger. Lipids are grouped with macromolecules though they're small, since they sit in the acid-insoluble fraction.
Nucleotides are made of a base, a sugar and phosphate. A nucleoside lacks the phosphate.

Proteins are polymers of amino acids joined by peptide bonds. RuBisCO is the most abundant protein in the biosphere, and collagen in animals.
Protein structure: primary (sequence), secondary (helix), tertiary (folding) and quaternary (subunits).
Polysaccharides: starch stores energy in plants, glycogen in animals, cellulose builds plant walls, and chitin builds exoskeletons.
Sugars join by glycosidic bonds, and nucleotides by phosphodiester bonds.

Almost all are proteins, though some nucleic acids act as ribozymes.
They speed up reactions by lowering activation energy.
The Michaelis constant Km is the substrate concentration at half of Vmax.
Competitive inhibitors resemble the substrate. For example, malonate inhibits succinic dehydrogenase.
Classes: oxidoreductases, transferases, hydrolases, lyases, ligases and isomerases.
Prosthetic groups are tightly bound, coenzymes are loosely bound, and metal ions can act as cofactors.

Calling lipids true polymers. They aren't, despite being in the macromolecule fraction.
Thinking an enzyme is used up, or changes the equilibrium of a reaction.
Mixing up nucleoside and nucleotide.

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