Dna

• DNA Replication


  1. DNA helicase unzips DNA into two strands

  2. DNA polymerase slides along strands and pairs free nucleotides with ones on original strands

  3. Hydrogen bonds form, creating two DNA molecules
• Mitosis


  Cell division where one parent cell divides into two identical (clone) daughter cells
• During mitosis, the DNA replicates to produce two copies
• DNA Helicase


  • Enzyme that unzips the DNA into two strands by breaking the hydrogen bonds between the bases
• DNA Polymerase


  • Enzyme that slides along the strands and pairs free nucleotides with the ones attached to the original strands
• Hydrogen bonds form, linking the two strands, resulting in two DNA molecules
• How semiconservative replication was proven

  1. Meselson and Stahl submerged E. coli bacteria in ammonium chloride with the nitrogen isotope being 'dense' (N-15)

  2. Cells were then transferred to a medium containing the isotope N-14, which is 'less dense'

  3. Bacteria were harvested and the DNA collected and dissolved in caesium chloride (CsCl)

  4. This was then put in a centrifuge and a concentration gradient was established

  5. After 1 generation, it showed a band of DNA of intermediate density
• Diagram

  • Observe the diagram below
• The concept was proven by two scientists named Meselson and Stahl
• Ribosomes


  Organelles that synthesize proteins, found in both eukaryotes and prokaryotes, attached to the rough endoplasmic reticulum
• Ribosomes contain ribosomal RNA (rRNA) and some protein
• Ribosomes


  • Have a large and small subunit
  • The large subunit helps hold substances like mRNA in place
  • The smaller subunit is more flexible
• rRNA can catalyze the formation of peptide bonds between amino acids when synthesizing proteins