11 Bio Chapter Summary

Biomolecules

Chapter Summary

  • All the carbon compounds which are obtained from living tissues are called biomolecules.
  • Amino acids are organic compounds which contain an amino group and an acidic group as substituents on the same carbon, i.e. α-carbon. Due to this, they are called α-amino acids.
  • Lipids are usually insoluble in water. Lipids can be simple fatty acids and some lipids have phosphorous and phosphorylated organic compounds in them.
  • Metabolites which have identifiable functions are called primary metabolites.
  • There are certain metabolites about which we do not have enough information to suggest their role in physiological processes. Such metabolites are called secondary metabolites.
  • Biomolecules with molecular eights less than one thousand Dalton are called micromolecules or simply as biomolecules.



  • Biomolecules with molecular weights more than one thousand Dalton are called biomacromolecules. These are found in the acid-insoluble fraction.
  • Protein is a polymer of amino acids. Based on similar or different monomers repeating in a protein, it is classified as homopolymer and heteropolymer.
  • Some amino acids are essential for our health. But our body does not make them and they need to be supplemented through diet. Such amino acids are called essential amino acids.
  • The long chains of sugars are called polysachharides. If a polysaccharide is made up of similar monosaccharides, it is called homopolymer, e.g. cellulose. If a polysaccharide is made up of different monosachharides, it is called heteropolymer.
  • A nucleic acid is composed of nucleotide. There are three chemically distinct components in a nucleotide. One of them is a heterocyclic compound, the second is a monosaccharide and the third is phosphoric acid or phosphate.
  • The sequence of amino acids is called the primary structure of a protein.
  • The protein is not a linear chain of amino acids rather the chain would bend at some places and even form helices. Regularly repeating local structures gives secondary structure to protein.
  • The overall shape of a protein molecule; and the spatial relationship of the secondary structures to one another; is called tertiary structure of protein. In other words, the various folds which give three dimensional appearances to protein form its tertiary structure.
  • The manner in which the individual folded polypeptides are arranged with respect to each other is called quaternary structure of protein.
  • Certain type of functional group which joins a sugar molecule to another group is called glycosidic bond.
  • A chemical bond formed between two molecules; when the carboxyl group of one molecule reacts with the amine group of another molecule; is called peptide bond (amide bond).
  • A group of strong covalent bonds between a phosphate group and two other molecules over two ester bonds is called a phosphor-diester bond. Phosphodiester bonds make the backbone of the strands of DNA and hence are central to all life on Earth.
  • All the biomolecules are constantly being changed into some other biomolecules and also made from some other biomolecules. The turnover of biomolecules takes place continuously. All these reactions are together called metabolism.
  • When a complex biomolecule is synthesized from simple biomolecules through a biological process, the process is called anabolism. Energy is utilised during anabolism.
  • When a complex biomolecule is disintegrated to produce simple biomolecules through a biological process, the process is called catabolism. Energy is released during catabolism.
  • Metabolites are converted into each other in a series of linked reactions. Such a series of linked reactions is called metabolic pathway.
  • An enzyme is a catalyst which is utilised in metabolic reactions. Almost all enzymes are proteins.
  • The lock and key model was suggested by Emil Fischer in 1894. Emil Fischer postulated that both the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another. This model explains the specificity of enzyme.
  • The induced fit model was proposed by Daniel Koshland in 1958. According to this model, since enzymes are rather flexible structures; the active site is continually reshaped by interactions with the substrate when the substrate interacts with the enzyme.
  • Enzyme lowers the activation energy by creating an environment in which the transition state is stabilized.
  • Temperature, pH, concentration of substrate, and effect of inhibitor are the factors that affect the activity of enzyme.
  • In many cases, non-protein constituents are bound to the enzyme which makes the enzyme catalytically inactive. Such non-protein constituents are called cofactors.