Molecular basis of inheritance practice · Mixed difficulty

Option A is correct. The complementary sequence is formed by replacing each base with its complement (A with T, G with C) and reversing the order.

Option D is correct because splicing is the process of removing introns (non-coding regions) and joining exons (coding regions) in pre-mRNA to form mature mRNA.

Option B (Frederick Sanger) is correct because Frederick Sanger developed the method for determining amino acid sequences in proteins.

Option C (A is false but R is true) is correct because DNA is not a static storehouse, it undergoes mutations, but it is indeed the carrier of genetic information.

Option D is correct because transversion is a type of point mutation where a purine base (A or G) is substituted with a pyrimidine base (C or T), or vice versa.

Option B is correct because tRNA carries amino acids from the cytoplasm to the ribosome.

Option C (Both b and d) is correct because adenine and guanine are purines, while cytosine, thymine, and uracil are pyrimidines.

Option D (a and c) is correct because rRNA is transcribed by RNA polymerase I and tRNA is transcribed by RNA polymerase III in eukaryotes.

Option B is correct because lactose acts as the inducer of the lac operon.

Option C is correct because tRNA constitutes about 10-20% of the total cellular RNA, playing a crucial role in carrying amino acids to the ribosome during protein synthesis.

Option A is correct because the coding strand has the same sequence as the mRNA (except T is replaced by U) and does not directly code for amino acids; the template strand is used to create the mRNA.

Option A is correct because DNA polymerase requires a free 3' OH group to add nucleotides during polymerization.

Option A (Purification of isolated protein) is correct because PCR is used to amplify DNA, not to purify proteins.

Option C (Topoisomerase) is correct because topoisomerases relieve the torsional stress caused by DNA unwinding during replication by cutting and rejoining DNA strands.

Option B (Protein Capsid of Phage) is correct because sulfur is present in proteins but not in DNA, so ${}^{35}S$ would be incorporated into the protein capsid of the bacteriophage.

Option D (DNA) is correct because Okazaki fragments are short DNA fragments synthesized on the lagging strand during DNA replication.

Option D is correct because ethidium bromide intercalates into DNA and fluoresces bright orange when exposed to UV radiation.

Option C (Bioinformatics) is correct because the Human Genome Project generated vast amounts of data, leading to the development of bioinformatics for data analysis and storage.

Option B ($32\%$) is correct because in DNA, A=T and G=C. If Adenine is 18%, Thymine is also 18%. The remaining percentage is split equally between Guanine and Cytosine.

Option D is correct because sickle-cell anemia is an autosomal recessive mutation, not an allosomal (sex-linked) one.

Option C (Two amino acids) is correct because after inserting adenosine, only two complete codons remain before a stop codon is encountered.

Option D (If both Assertion and Reason are false) is correct because a change in the third position of a codon often does NOT change the amino acid due to wobble base pairing, and a codon is read by all three bases, but the third base has more flexibility.

Option B (254) is correct because the calculation involves determining the number of A-T and G-C base pairs and using the number of cytosine molecules to find the number of hydrogen bonds.

Option C ($4.0 \times 10^6 \mathrm{bp}$) is correct because dividing the length of the E.coli DNA by the distance between base pairs gives the number of base pairs, which is approximately 4 million.

Option B is correct because the 3' OH group is essential for forming the phosphodiester bond during nucleotide addition; removing or replacing it would prevent polymerization.

Option C (Promoter, Structural gene, Terminator) is correct because a transcription unit is defined by the promoter, structural gene, and terminator regions.

Option C (UGG : Non degenerate) is correct because UGG codes only for tryptophan and is therefore non-degenerate.

Option A is correct because the enzymes involved in DNA replication are efficient, capable of polymerizing a large number of nucleotides quickly, making both the assertion and reason true, with the reason explaining the assertion.

Option D (Gene therapy) is correct because gene targeting involving gene amplification to treat disease is the definition of gene therapy.

Option D (Nirenberg and Mathaei) is correct because Nirenberg and Mathaei's experiments cracked the genetic code and demonstrated that it is a triplet code.