Molecular Basis of Inheritance Test - 8

Jacob and Monod (1961) gave the concept of Operon model to explain the gene regulation in prokaryotes using simple experiments to grow E. coli in petriplates containing histidine, lactose or lactose and glucose in the medium.

Griffith's experiment, was an experiment done in 1928 by Frederick Griffith. It was one of the first experiments showing that bacteria can get DNA through a process called transformation.

Griffith carried out experiment on mice using pneumonia causing bacteria to show that DNA is the genetic material by transforming non-virulent strain into virulent strain which is called bacterial transformation.

The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. It is found floating freely inside the nucleus.

Regulator genes codes for repressor proteins during translation of DNA into protein via mRNA.

Until about 20 years ago, all known enzymes were proteins. But then it was discovered that some RNA molecules can act as enzymes; that is, catalyze covalent changes in the structure of substrates (most of which are also RNA molecules). Catalytic RNA molecules are called ribozymes.

Only a few RNA molecules act as enzymes.

During protein synthesis, elongation of peptide chain is catalyzed by the enzyme RNA polymerase. Elongation continuous until a non-sense or stop codon is reached.

Exons are coding sections of an RNA transcript, or the DNA encoding it, that are translated into protein. Exons can be separated by intervening sections of DNA that do not code for proteins, known as introns.

Signaling between cells for transcription of m-RNA from DNA is controlled by an activation of protein kinases. It is present in cytoplasm of cells.

Regulator gene is a gene that regulates the expression of one or more structural genes by controlling the production of a protein (such as a genetic repressor) which regulates their rate of transcription. Regulation of lac operon by repressor is called negative regulation.