CBSE Questions for Class 12 Medical Biology Molecular Basis Of Inheritance Quiz 4 - MCQExams.com

• 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. 
• They signal the release of the nascent polypeptide from the ribosome because there is no cognate tRNA that has anticodons complementary to these stop signals, and so a release factor binds to the ribosome instead.
  Hence, the correct option is B.

Correct Option: B

Explanation:

• Replication is the process of the formation of a new DNA strand from the template DNA.
• Translation is the formation of protein from an mRNA.
  Transduction is the transfer of the genetic material from a bacterium to another through a bacteriophage.
• Transcription is the process of the formation of a new strand of RNA from the template DNA.

Hence, multiplication of DNA is called as replication. 

• The method by which information reaches from DNA to RNA is called transcription. 
• The translation is the process by which a cell makes proteins using the genetic information carried in mRNA.
  
• Genetic transformation involves the transfer and incorporation of foreign DNA into a host genome. 
  
• Transduction is the process by which a virus transfers genetic material from one bacterium to another. 
  

Correct Option: A
Explanation:

• Translation is initiated with a chain initiation codon and terminates with a stop codon.
• The initiation codon is the first codon of a messenger RNA translated by a ribosome.
• AUG codes for methionine in eukaryotes.

Hence, AUG is an initiation codon.

Correct Option: B
Explanation:

• The process of RNA synthesis from DNA is called transcription. During transcription, the complete gene is copied into a pre-mRNA along with exons and introns.
• The exons are the coding regions and the introns are the non-coding regions. The process of RNA splicing converts the pre-mRNA to mRNA and involves the removal of introns and the joining of exons.
• This results in the formation of the mature mRNA that is translated into a protein.

Francis Crick and James D. Watson published an article entitled as "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid" in the scientific journal Nature dated 25 April 1953 which described the discovery of the double helix structure of DNA. The above quote refers to the fact the complementary base pairing is key to the double helical structure of DNA and the same pairing facilitates the synthesis of new DNA strands using parental DNA strand as a template.
As we know that new DNA molecules are synthesized during replication which is a semi-conservative mechanism and forms a daughter DNA duplex carrying one parental and one new strand. This copying mechanism ensures inheritance of genetic information, present on DNA, from parents to offspring.