Lecture Notes: Overview of DNA and RNA

Key Concepts

• DNA Structure and Function

  • DNA (Deoxyribonucleic acid) is responsible for storing and transmitting genetic information.
  • Composed of two strands forming a double helix.
  • Nucleotides are the building blocks of DNA, consisting of a sugar, phosphate group, and nitrogenous base.
  • Four nitrogenous bases: adenine (A), thymine (T), cytosine (C), guanine (G).
  • Base pairing rules: A pairs with T, and C pairs with G.

• RNA Structure and Function

  • RNA (Ribonucleic acid) is crucial for translating genetic information from DNA into proteins.
  • Single-stranded molecule.
  • Contains ribose sugar instead of deoxyribose.
  • Uracil (U) replaces thymine (T) in RNA.

DNA Replication

• Process Overview
  • Semi-conservative replication: each new DNA molecule consists of one old strand and one new strand.
  • Key enzymes: DNA helicase, DNA polymerase, and DNA ligase.
  • Steps include unwinding of the double helix, complementary base pairing, and joining of nucleotides.

Transcription and Translation

• Transcription

  • Process of copying a segment of DNA into RNA.
  • Takes place in the nucleus.
  • mRNA (messenger RNA) is synthesized.

• Translation

  • Occurs in the ribosome, converting mRNA into a polypeptide chain (protein).
  • tRNA (transfer RNA) brings amino acids to the ribosome.
  • Codons on mRNA are read in triplets, each corresponding to a specific amino acid.

Genetic Code

• Characteristics
  • Universal: Same genetic code across most organisms.
  • Degenerate: Multiple codons can code for the same amino acid.
  • Non-overlapping: Codons are read one at a time.

Regulation of Gene Expression

• Mechanisms
  • Regulatory proteins can influence gene expression.
  • Operons in prokaryotes are a major method of regulation.
  • Eukaryotic regulation involves transcription factors and epigenetic mechanisms.

Mutations

• Types and Effects
  • Point mutations: Changes in a single nucleotide pair.
  • Frameshift mutations: Insertions or deletions that alter the reading frame.
  • Can lead to genetic disorders or cancer.

Biotechnological Applications

• DNA Technology
  • Recombinant DNA technology allows for gene cloning.
  • PCR (Polymerase Chain Reaction) is used to amplify DNA.
  • CRISPR-Cas9 allows for precise gene editing.

These notes cover the basics of DNA and RNA structure, replication, transcription, translation, genetic code, gene regulation, mutations, and applications in biotechnology. Understanding these concepts is crucial for further studies in molecular biology and genetics.