Molecular Basis of Inheritance Test - 86

There are 110 thymine and 110 guanine bases in the double-stranded DNA molecule. The number of thymine will be equal to adenine which will form the pair with the help of hydrogen bonds and so there are 110 adenine. Similarly, for guanine, there will be 110 cytosine to base pair with guanine. So, the total number of nitrogen bases are 440.

A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward. 

There are three codons that do not code for any amino acid called the stop codons. They are UAG, UAA, UGA.

Marshall Nirenberg and Heinrich J. Matthaei were the first to elucidate the nature of a codon in 1961 at the National Institutes of Health. They used a cell-free system to translate a poly-uracil RNA sequence and discovered that the polypeptide that what they had synthesized consisted of only the amino acid phenylalanine.They, thereby, deduced that the codon UUU specified the amino acid phenylalanine.

• The Human Genome Project (HGP) is an international scientific research project with the goal of determining the sequence of chemical base pairs which make up human DNA and of identifying and mapping all the genes of the human genome from both a physical and functional standpoint. 
• It remains the world's largest collaborative biological project. 
• The US government proposed and funded the project; planning started in 1984, the project got underway in 1990 and was declared complete in 2003. 
• The DOE, European Commission, and the NIH established working groups to address genome mapping, computational analysis to handle databases, and the social, legal, and ethical implications of human genome research.

The primary nucleobases are cytosine (DNA and RNA), guanine (DNA and RNA), adenine (DNA and RNA), thymine (DNA) and uracil (RNA), abbreviated as C, G, A, T, and U, respectively. Because A, G, C, and T appear in the DNA, these molecules are called as DNA-bases; A, G, C, and U are called as RNA-bases. Adenine and guanine belong to the double-ringed class of molecules called as purines (abbreviated as R). Cytosine, thymine, and uracil are all pyrimidines (abbreviated as Y). In normal spiral DNA, the bases form pairs between the two strands: A with T and C with G. Purines pair with pyrimidines mainly for dimensional reasons - only this combination fits the constant width geometry of the DNA spiral. The A-T and C-G pairings are required to match the hydrogen bonds between the amine and carbonyl groups on the complementary bases. 

Hence, a DNA strand with 80 thymine and 80 guanine bases will have 80 adenine and 80 cytosine bases. This makes total 80+80+80+80 = 320 bases and therefore, 320 nucleotides in that DNA molecule. 

Proteins are made up from a set of 20 amino acids called standard amino acids. A three letter code of nucleotides called codon specify for amino acids. Polypeptide synthesis proceeds from a N-terminus to C-terminus  and ribosome reads mRNA in the 5' to 3' direction. Three kinds of RNA molecules perform different but cooperative functions in protein synthesis. mRNA carries the genetic information copied from DNA in the form of a series of these three letter code words. There are in total 64 codons . Out of these, 61 codons code for amino acids whereas 3 codons donot code for any amino acid. These three codons UAA, UAG and UGA are termed as stop codons as when these are read by the ribosomes no amino acid is incorporated. Rather the protein synthesis terminates. Protein synthesis begins with codon termed as initiator codon generally AUG. In eukaryotes this codon codes for methionine whereas in prokaryotes this codes for N-formylmethione. Protein synthesis initiates with a initiator codon in the mRNA and terminates with the stop codon. In the given sequence there are eight codons. But since the fourth codon is UAA which is a stop codon the translation process will terminate there and a protein of 3 amino acids will be synthesized. All other options are hence incorrect and D is the correct answer.