Tag: the origin of cells and cell division

Endonucleases hydrolyse internal phosphodiester bonds in a polynucleotide chain. Function of nucleases is to break phosphodiester bond. A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Nucleases are usually further divided into endonucleases and exonucleases, although some of the enzymes may fall in both categories. 

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

• In 1897, Eduard Buchner discovered that yeast extracts could ferment sugar to alcohol, proving that fermentation was promoted by molecules that continued to function when removed from cells. Frederick W. Khne called these molecules like enzymes.
  Hence, the correct option is B.

The enzyme that cause chromosomal breaks are DNase. A deoxyribonuclease or DNase, is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. Deoxyribonucleases are one type of nuclease, a generic term for enzymes capable of hydrolising phosphodiester bonds that link nucleotides.

Enzymes are biological catalysts, which activate various biochemical reactions of a living cell in a highly specific and precise manner. Enzymology is the study of enzymes. The name enzyme was coined by Kuhne in 1878. Pasteur recognised that some microorganisms like yeasts have got a capacity to cause fermentation in wine. In 1897, Buchner discovered that yeast extract could bring about fermentation of grape juice, like the living yeast cells. He also observed that the extract has lost its catalytic activity on boiling. He coined the word zymase for the active principle involved in the fermentation. The substance on which the enzyme acts is called substrate. Enzymes are essentially proteins but all proteins are not enzymes.

Buchner coined the term zymase for the complex of biocatalysts extracted from yeast and taking part in alcoholic fermentation. Pasteur is responsible for the process of pasteurization and Kuhne is best known today for coining the word enzyme.

Rennin is a protease found in rennet. It is produced by newborn ruminant animals in the lining of the fourth stomach to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese.

Dehydrogenases are the enzymes which catalyze oxidation-reduction reactions by addition or removal of electrons. These reactions are used to synthesize reduced coenzymes like NADH$ _2$ and FADH$ _2$. For example phosphoglyceraldehyde dehydrogenase.