Biology Class 12 Chapter 4 Quiz
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Questions and Answers

What is the role of 'hnRNA' in the transcription process in eukaryotes?

  • Directly involved in translation process
  • The initial transcript before processing into mature mRNA (correct)
  • Responsible for splicing and capping of mRNA
  • The final mRNA product ready for translation
  • Which characteristic distinguishes heterochromatin from euchromatin?

  • Heterochromatin is always found near the nuclear membrane, while euchromatin is centrally located
  • Heterochromatin is actively transcribed, while euchromatin is transcriptionally silent
  • Heterochromatin stains darkly due to high gene activity, while euchromatin stains lightly due to gene inactivity (correct)
  • Heterochromatin is loosely packed with active genes, while euchromatin is condensed and gene-poor
  • What is the role of 'TATA box' in the process of transcription?

  • Facilitates splicing and processing of hnRNA
  • Serves as a recognition site for RNA polymerase to start transcription (correct)
  • Binds to ribosomes for protein synthesis
  • Initiates translation of mRNA
  • Which part of the DNA molecule is involved in the synthesis of new complementary strand during replication?

    <p>Origin of replication</p> Signup and view all the answers

    What is the function of 'capping' in RNA processing?

    <p>Protects the mRNA from degradation and assists in export from the nucleus</p> Signup and view all the answers

    What is the significance of the 'human genome project'?

    <p>To map all genes in human DNA and understand their functions</p> Signup and view all the answers

    Study Notes

    hnRNA and Transcription in Eukaryotes

    • hnRNA (heterogeneous nuclear RNA) is the primary transcript in eukaryotic cells, containing both exons and introns.
    • It undergoes processing, including splicing, capping, and polyadenylation, to produce mature mRNA.
    • hnRNA represents the initial product of transcription before modifications facilitate transport to the cytoplasm for translation.

    Heterochromatin vs. Euchromatin

    • Heterochromatin is densely packed, transcriptionally inactive, and often associated with gene silencing.
    • Euchromatin is less condensed, transcriptionally active, and contains genes that are frequently expressed.

    TATA Box Role in Transcription

    • The TATA box is a conserved DNA sequence located upstream of the transcription start site.
    • It plays a crucial role in recruiting transcription factors and RNA polymerase II to initiate the transcription process.
    • This sequence ensures proper orientation and positioning for the formation of the transcription initiation complex.

    DNA Synthesis during Replication

    • The synthesis of a new complementary strand takes place at the replication fork during DNA replication.
    • DNA polymerase adds nucleotides complementary to the existing template strand, ensuring accurate duplication of the genetic material.

    Function of Capping in RNA Processing

    • Capping involves the addition of a modified guanine nucleotide to the 5' end of the hnRNA molecule.
    • This modification protects mRNA from degradation and assists in ribosome recognition during translation initiation.

    Significance of the Human Genome Project

    • The Human Genome Project was an international effort aimed at sequencing and mapping all human genes.
    • It has provided invaluable insights into genetic diseases, human evolution, and personalized medicine.
    • The project has also laid the groundwork for advancements in genomics and biotechnology.

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    Description

    Test your knowledge on DNA replication, amino acids in polypeptide chains, heterochromatin vs euchromatin, and transcription process in this quiz focused on Chapter 4 of Biology for Class 12.

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