Quiz

Description of Topics Covered in the MCQs

Here is a detailed description of the key topics covered in the MCQs on nucleic acids:

Nucleic Acids and Nucleotides

• Nucleic acids (DNA and RNA) are polymers of nucleotides.
• A nucleotide consists of three components: a nitrogenous base, a pentose sugar, and a phosphate group.
• DNA and RNA differ in their sugar components and nitrogenous bases.

 Nitrogenous Bases

• There are two types of nitrogenous bases:
  • Purines: Adenine (A) and Guanine (G).
  • Pyrimidines: Cytosine (C), Thymine (T), and Uracil (U).
• DNA contains Thymine, whereas RNA contains Uracil.

Central Dogma of Molecular Biology

• The central dogma explains the flow of genetic information:
  DNA → RNA → Protein.
• It involves two main processes:
  • Transcription: Synthesis of RNA from DNA.
  • Translation: Conversion of RNA into proteins

Genetic Code

• The genetic code is carried by the sequence of nitrogenous bases in DNA.
• It determines the sequence of amino acids in proteins.

Genome

• The complete set of an organism’s DNA is called its genome.
• The human genome consists of approximately 3 billion base pairs, encoding all genetic information.

DNA and RNA

DNA Structure

• DNA has a double-helical structure, as described by Watson and Crick.
• The strands are held together by hydrogen bonds between complementary bases:
  • Adenine pairs with Thymine (A-T) using two hydrogen bonds.
  • Guanine pairs with Cytosine (G-C) using three hydrogen bonds.
• The backbone of DNA is made of alternating sugar and phosphate groups linked by phosphodiester bonds.

DNA Replication

• DNA replication is the process of synthesizing a new DNA strand.
• Key enzymes involved:
  • Helicase: Unwinds the DNA helix.
  • DNA Polymerase: Adds nucleotides to the growing strand.
  • Ligase: Joins DNA fragments on the lagging strand.
• Replication is semi-conservative: Each new DNA molecule has one old and one new strand.

RNA Structure

• RNA is single-stranded and contains ribose sugar.
• It replaces Thymine with Uracil, which pairs with Adenine.

Types of RNA

• Messenger RNA (mRNA): Carries the genetic code from DNA to the ribosome for protein synthesis.
• Transfer RNA (tRNA): Brings amino acids to the ribosome during translation.
• Ribosomal RNA (rRNA): Forms the structural and functional core of ribosomes.

Differences Between DNA and RNA

DNA and RNA Functions

• DNA: Stores and transmits genetic information.
• RNA: Plays roles in protein synthesis (mRNA, tRNA, rRNA) and regulatory functions (e.g., snRNA).

Location of DNA and RNA

• In prokaryotes, DNA is found in the cytoplasm as a circular chromosome.
• In eukaryotes, DNA is found in the nucleus, mitochondria, and chloroplasts. RNA is synthesized in the nucleus and functions in the cytoplasm.

This comprehensive overview aligns with the MCQs and provides clarity on nucleic acids, their structure, functions, and biological significance.

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