DNA, DNA REPLICATION, DNA TRANSITION AND TRANSCIPTION

• The process of transcription involves the synthesis of mRNA from a template strand of DNA.
• DNA


  Deoxyribonucleic acid
• DNA carries genetic information
• Nucleotides


  Repeating units that make up DNA
• Components of a nucleotide

  • Sugar (deoxyribose)
  • Phosphates
  • Nitrogeneous bases
• DNA replication is important for cell division
• Purposes of cell division

  • Growth
  • Repair
  • Replacement
• Before cells divide they have to double cell structures, organelles and their genetic information
• Semi-conservative


  One strand is the original (conserved) and another strand is freshly assembled (semi-half)
• DNA replication


  1. Helicase opens or unwinds the DNA and replication forks are formed

  2. The DNA is coated by single-strand binding proteins around the replication fork to stabilize the DNA

  3. The leading strand is synthesized continuously in the 5' to 3' direction by the DNA polymerase

  4. Primase synthesizes a short RNA Primer, which is extended by DNA polymerase to form an Okazaki fragment.

  5. RNA primer is replaced by DNA. DNA ligase joins the Okazaki fragments.
• DNA (Deoxyribonucleic acid)

  -Carries genetic information

  -Made up of repeating units called nucleotides.

  -A nucleotide consist of sugar (deoxyribose), phosphates and nitrogeneous bases
• Why is DNA replication important?

  • Cell division

  -Growth, Repair, Replacement

  -Before cells divide they have to double cell structures, organelles and their genetic information.

  -DNA replication is said to be Semi- conservative because: One strand is the original (conserved) and another strand is freshly assembled (semi-half)
• DNA REPLICATION STEP

  STEP 1

  Helicase opens or unwinds the DNA and replication forks are formed.

  STEP 2

  The DNA is coated by single-strand binding proteins around the replication fork to stabilize the DNA

  STEP 3

  The leading strand is synthesized continuously in the 5' to 3' direction by the DNA polymerase

  STEP 4

  Primase synthesizes a short RNA Primer, which is extended by DNA polymerase to from an Okazaki fragment.

  STEP 5

  RNA primer is replaced by DNA. DNA ligase joins the Okazaki fragments. 
• The process of transcription involves the synthesis of mRNA from a template strand of DNA.