What is transcription with reference to protein synthesis? How does it take place?
Transcription means copying the sequence of bases from DNA on messenger RNA (m-RNA). The copying of DNA sequence into m-RNA proceeds according to the same base pairing principle as in replication but differ in the following two respects:
(i) During m-RNA synthesis, the DNA double helix structure opens up and the ribonucleotides assemble along the uncoiled strand of DNA.
(ii) The base adenine (A) in DNA strand pair up with the uracil (U) in RNA.
After transcription, the m-RNA-DNA double helix separates. The m-RNA detaches itself and migrates to cytoplasm, while the DNA returns to its double helix structure.
Explain the following:
Glucose responds Fehling solution and osazone, it does not react with Schiff’s base and sodium bisulphite.
Explain the following:
Glucosides react neither with Fehling solution nor with Tollen's reagent. They also do not allow mutarotation.
Explain the following:
Although fructose does not have an aldehydic group, it reacts with Fehling solution.
What is melting temperature (Tm) of DNA? A DNA molecule with more number of GC base pairs than AT base pairs has higher Tm than the one with lesser number of GC base pairs than AT base pairs. Explain why?
Which vitamin is called ascorbic acid? What are its physiological functions? Which disease is caused by the deficiency of this vitamin?
What are forces holds the two strands of DNA together in a double-helix structure? Draw structure to show the bonding between adenine and thymine, and between guanine and cytosine.
