NEET Practice Questions (MCQs) with Answers & Solutions

Ribosomal RNA (rRNA) is actively synthesized in the nucleolus. The nucleolus is a region within the nucleus where rRNA is transcribed and assembled into ribosomal subunits. This makes the nucleolus the main site for rRNA synthesis.

AUG has dual purpose-

1.it codes for methionine 

2. it is the start codon 

The semiconservative model of DNA replication using extsuperscript{15}N (heavy nitrogen) was demonstrated by Matthew Meselson and Franklin Stahl. In their famous experiment, they used density gradient centrifugation to show that DNA replication involves each of the two parent strands serving as a template for a new strand, resulting in two daughter DNA molecules, each with one old and one new strand.

In the operon model, the operator gene binds with the repressor protein (produced by the regulator gene) to switch off the transcription of structural genes. When the repressor is bound to the operator, RNA polymerase is blocked from transcribing the genes within the operon. This is a key regulatory mechanism in prokaryotic gene expression.

Termination of chain growth in protein synthesis is brought about by UAA, UAG, UGA. Translation starts with a chain initiation codon or start codon and terminates with a stop codon. 

The three stop codons have been given names : UAG is amber, UGA is opal, and UAA is ochre. Stop codons are also called "termination" or "nonsense" codons.

Transfer RNAs (tRNAs) decipher the mRNA information and transfer the appropriate amino acid to a growing polypeptide chain during protein synthesis.

The correct sequence of code transfer during polypeptide formation is: DNA -> mRNA -> tRNA -> amino acids. This is the central dogma of molecular biology. The genetic information is transcribed from DNA to mRNA, which then travels to the ribosome. At the ribosome, tRNA brings the appropriate amino acids in sequence to form a polypeptide chain.

The best method to determine paternity is DNA fingerprinting. DNA fingerprinting analyzes the unique patterns in an individual's DNA, making it highly reliable for identifying biological relationships, including paternity.

A DNA nucleotide chain has complementary base pairing: Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G). Given the sequence AGCTTCGA, the complementary sequence would be TCGAACT, corresponding to option o1.