Molecular Basis of Inheritance MCQs for NEET — Botany Questions with Answers

The formation of the lagging strand is indeed slower than the leading strand because it is synthesized in short, discontinuous segments known as Okazaki fragments. This is due to the fact that DNA polymerase can only synthesize DNA in the 5' to 3' direction, and the lagging strand template is oriented in the 3' to 5' direction. Therefore, the synthesis of the lagging strand begins a bit later than the leading strand as it must wait for the replication fork to open further. Hence, both Assertion (A) and Reason (R) are true, and Reason (R) correctly explains Assertion (A).

In the given scenario, the original codon (UAU) codes for the amino acid Tyrosine. When it mutates to UAA, it becomes a stop codon. This means that translation will terminate prematurely at this point. Therefore, instead of a polypeptide of 50 amino acids, only the first 24 amino acids will be formed before the translation process stops at the 25th codon. Hence, a polypeptide of 24 amino acids will be formed.

The 'lac' in 'lac operon' stands for 'lactose'. The lac operon is a set of genes with a single promoter that are involved in the metabolism of lactose in Escherichia coli and some other bacteria. When lactose is present, it acts as an inducer by binding to the repressor and allowing transcription of the operon's genes to proceed.

During transcription, the DNA sequence is transcribed into mRNA. The base pairing rules are as follows: Adenine (A) pairs with Uracil (U) in RNA, and Cytosine (C) pairs with Guanine (G). Therefore, if the DNA sequence being coded is ATACG, the complementary mRNA sequence would be UAUGC.

Reverse transcriptase is an enzyme that transcribes RNA into DNA. It is used by retroviruses to integrate their genetic material into the host genome. This process is crucial in molecular biology, especially in the context of retroviruses like HIV.

The z gene in the lac operon codes for the enzyme beta-galactosidase. This enzyme is responsible for breaking down lactose into glucose and galactose. A mutation in the z gene means that E. coli cannot produce functional beta-galactosidase, thereby making it unable to utilize lactose as an energy source.

The sequence of amino acids in protein synthesis is determined by the sequence of mRNA. During translation, the mRNA sequence is read by the ribosome, and tRNA molecules bring the corresponding amino acids to form a polypeptide chain.

The term 'antiparallel' in the context of DNA refers to the orientation of the two strands of the DNA molecule. In an antiparallel arrangement, the phosphate groups at the start (5' end) of one strand are aligned opposite to the phosphate groups at the start (5' end) of the other strand. This means one strand runs in the 5' to 3' direction, while the complementary strand runs in the 3' to 5' direction.