Cellular and Molecular Biology

• What are the key processes of genetic exchange discussed in Lecture 3?

  • Transformation
  • Conjugation
  • Transduction
• What does the central dogma of molecular biology describe?

  The flow of genetic information within a biological system
• What is the role of transcription in the central dogma?

  It synthesizes messenger RNA (mRNA) from a DNA template
• What is the sequence of information flow in the central dogma of molecular biology?

  DNA → RNA → Protein
• What occurs during translation in the central dogma?

  Ribosomes read mRNA and synthesize proteins
• Why are proteins essential for cellular functions?

  They perform structural roles and catalyze biochemical reactions
• What is the functional unit of genetic information?

  A gene
• What is the genome?

  All genetic elements within an organism
• What are the three components of nucleotides?

  Pentose sugar, nitrogenous base, phosphate
• What are the two types of nitrogenous bases?

  Pyrimidines and purines
• Which nitrogenous bases are purines?

  Adenine (A) and Guanine (G)
• Which nitrogenous base is found only in DNA?

  Thymine (T)
• Which nitrogenous base is found only in RNA?

  Uridine (U)
• What are the differences between DNA and RNA?

  • DNA: double-stranded, deoxyribose sugar, thymine (T)
  • RNA: single-stranded, ribose sugar, uracil (U)
• What is the genetic code?

  A set of rules for translating DNA or RNA sequences into proteins
• How many codons are there, and how many amino acids do they encode?

  64 codons encode for 20 amino acids
• What does redundancy in the genetic code mean?

  Several codons can encode for the same amino acid
• Why is understanding the genetic code important?

  It has led to advancements in genetic engineering, biotechnology, and medicine
• What are the mechanisms of genetic exchange?

  • Vertical gene transfer: from parent to offspring
  • Horizontal gene transfer: between organisms, often across species
• What is vertical gene transfer?

  Transmission of genetic material from parent to offspring
• What is horizontal gene transfer (HGT)?

  Transfer of genetic material between organisms that are not offspring
• What are the three mechanisms of horizontal gene transfer?

  1. Transformation
  2. Conjugation
  3. Transduction
• What is transformation in the context of genetic exchange?

  Prokaryotes uptake DNA from the environment and recombine it into their genome
• What are competent cells?

  Cells that can take up DNA from the environment
• How was natural transformation discovered?

  Frederick Griffith observed that capsule-bearing strains of Streptococcus pneumoniae killed mice
• What is the capsule in Streptococcus pneumoniae?

  A polysaccharide/amino acid structure that helps microbes adhere and protects against phagocytosis
• What were the conclusions from Griffith's experiment?

  Heat-killed virulent bacteria could transform non-virulent bacteria into a virulent form
• What is the molecular mechanism behind natural transformation?

  Exogenous double-stranded DNA binds to proteins in the cell membrane and is integrated into the chromosome
• What is single-strand assimilation in natural transformation?

  Integration of a strand of DNA into the chromosome if it is homologous to existing DNA
• What is the role of RecA protein in natural transformation?

  It invades the homologous region in the cell chromosome and facilitates DNA integration
• What are the two methods for introducing DNA into bacteria in molecular biology?

  • Chemically competent cells and heat shock method
  • Electrocompetent cells and electroporator
• What is gene cloning?

  Introducing recombinant DNA into cells artificially
• What type of DNA binds to proteins in the competent system of the cell membrane?

  Stranded DNA (dsDNA)
• What happens to dsDNA after it binds to the competent system?

  It is fragmented into smaller pieces.
• What occurs to one strand of the dsDNA during the process?

  One strand is degraded by a nuclease.
• What protects the inserted DNA from degradation in the cytoplasm?

  Transformation-specific DNA-binding protein (RecA proteins)
• What is the process called when a strand of DNA integrates into the chromosome?

  This is called single-strand assimilation.
• What is the function of RecA protein?

  It is essential for the repair and maintenance of DNA.
• What does RecA do when it invades the homologous region in the cell chromosome?

  It displaces one of the existing strands and replaces it with the new DNA.
• What does homologous mean in the context of DNA?

  Similar in position, structure, and evolutionary origin but not necessarily in function.