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Molecular Basis Of Inheritance Class 12 Important Questions And Answers MCQ PDF

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Molecular basis of inheritance class 12:- The nucleic acids consist of long polymers of the nucleotides.While the DNA stores the genetic information,the RNA helps in the transfer and expression of information. Though the DNA and the RNA both works as the genetic material but the DNA being chemically and structurally more stable is a better genetic material.

Molecular Basis Of Inheritance Class 12
Molecular Basis Of Inheritance Class 12

Molecular basis of inheritance class 12 – Very Short Answer Type Questions

Q.1. Write the function of the histones in DNA packaging.

A.1. Following are the function of histones in DNA packaging:

  • This plays a role in the gene regulation.
  • Histone  helps in  the DNA to wind around it.
  • This is positively charged proteins that can easily bind to the negatively charged DNA.

Q.2. Write the difference between the heterochromatin and  the euchromatin?

A.2.The Heterochromatin is a tightly packed DNA that can be identified when they  stained in an extreme nuclear stain.

The Euchromatin is a lightly packed DNA that can be identified when they stained in a less nuclear stain.

Molecular basis of inheritance class 12 study materials

Q.3.Write the  name of  any three viruses with RNA as the genetic material.

A.3. Viruses in which the RNA works as genetic material  are known as the RNA virus. The three examples of the RNA virus.

  1. Human Immunodeficiency Virus.
  2. Influenza Virus.
  3. Hepatitis C Virus.

Q.4. Write the reason for the discontinuous synthesis of the DNA on one of the parental strands?

A.4. In the biological process of the DNA synthesis naturally occurs in 5′ to 3′ directions. In the double-stranded DNA, strands are parallel and antiparallel to each other. During the synthesis of the DNA, both the strands act as template strand  and only one (3′ to 5′ direction) can synthesize the parallel strand in 5’→3′ direction. The other strand 5′ to 3′ is synthesized in the opposite direction producing the small stretches of the DNA called as Okazaki fragments. It is the only reason for the discontinuous synthesis of the DNA on one of the parental strands.

Q.5. The sequence of the coding strand of the DNA in a transcription unit is given below.

3′ AATGCAGCTATTAGG 5′

Write the sequence for this:

  1. For its complementary strand
  2. For its
  3. s mRNA

A.5.

  1. complementary strand is  5′ TTACGTCGATAATCC 3′
  2.  mRNA is  5′ AUGCUGAAUUG 3′

Q.6. Define DNA polymorphism?

A.6. DNA’s polymorphism is the variation in the DNA sequence arising because of the mutation at non-coding sequences.

Q.7. The Retroviruses do not follow the central dogma.  Write a comment on this statement

A.7. The Retroviruses do not follow the central dogma, because they possess the RNA as genetic material instead of the DNA, that is later converted into the DNA by the enzyme reverse transcriptase.

Molecular basis of inheritance class 12 Quiz

Q.8. Sometimes, young ones born have an extremely different set of eyes or limbs. Write an explanation for the abnormality.

A.8. This abnormality is caused due to many factors, including the alcohol abuse by the mother during her pregnancy, the medicine side effects or reactions caused due to the womb,  the environmental factors, such as the maternal exposure to the chemicals, radiations, the virus, and it can also be caused due to the genes and the non-coordination in the regulation of the expression in the set of genes associated with the development of organs.

Q.9. Describe the dual polymerase present in the E.coli.

A.9. The DNA polymerase present in the E.coli is the DNA dependent polymerase. This DNA polymerase helps in the following way:

  1. In the Replication process.
  2. It Performs the 5′ to 3′ polymerase activity as well as the 3′ to 5′ exonuclease activity.
  3. The DNA polymerase will also have the ability to proofread the wrong nucleotides and then  substitute it with the correct one.

Q.10. Write the functions of the :

  1. Methylated guanosine cap
  2. Poly-A tail

A.10.

  1. The Methylated guanosine can play a primary role in  attachment of the mRNA to the smaller subunits of the ribosome during  the translation initiation.
  2. Poly-A tail functions by the  increasing the length of the mRNA and also it provides the longevity to the mRNA.

Q.11. Write  two functions of the AUG codon.

A.11. The AUG codon is also known as the start codon. The two important functions of AUG codon is following:

  1. It codes for the methionine.
  2. It acts as an initiation codon for the protein synthesis.

Q.12. Write the function of the aminoacyl t-RNA synthetase.

A.12. Aminoacyl t-RNA synthetase plays a major  or important role in the biosynthesis of the proteins by attaching an appropriate amino acid to the tRNA molecules.

Molecular basis of inheritance class 12 – Long Answer Type Questions

Q.1. Describe the post-transcriptional modifications in a eukaryotic mRNA.

A.1. The Transcription is the process of the conversion of the DNA to the mRNA. The post-transcriptional modifications includes:

  • Capping at 5’-end
  • Poly-A tail at 3’-end
  • mRNA splicing

The 5′ cap protects the RNA from the ribonuclease. The poly-A tail protects the mRNA from the enzymatic degradation. The introns are spliced during the mRNA splicing and the exons are joined together to form a continuous sequence which codes for a functional protein.

Q.2. Describe the process of the translation.

A.2. The translation is the process of protein synthesis in that  the mRNA is used to synthesize the proteins. mRNA sequence is decoded to the specify the amino acid of the polypeptide. This process of translation is carried out in the following steps:

  • Initiation.
  • Elongation.
  • Termination.

Q.3. Write about the process of DNA fingerprinting.

A.3. The DNA fingerprinting is a technique which is used to analyze the genetic makeup of the living beings. It is widely used for the  DNA analysis in the forensic tests and the paternity tests to identify the biological parents of the child, and also to the identify the criminal during forensic investigations.

Q.4. Define an operon.Explain the causative operon.

A.4. An operon is  functional unit of the DNA which  contains a cluster of genes that is controlled by a single promoter. It consists of the following components:

  • The DNA fragment which  transcribes the mRNA.
  • It Regulator gene which codes for the repressor protein.
  • The Inducer which prevents to the repressor from binding to the operator.
  • An operator which is a DNA sequence that is adjacent to the promoter where the repressor protein binds.

The lac operon of E.coli is an causative operon.

Q.5. Illustrate the process of the DNA replication.

A.5. The DNA replication is a biological process of producing the two identical strands of the DNA from the original strand. The original strand is called as the parent strand and the new strands are called as the daughter strands. Which is achieved by a number of the enzymes such as DNA polymerase,  primase, topoisomerase, and ligase etc.

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