Gene expression

• The genetic code is universal , degenerate and non-overlapping.
• DNA stores genetic information in a cell , this gets transcribed into the RNA and then translated into proteins.
• Changes to coding DNA (exons) can result in changes to the amino acid that is coded for a specific protein.
• The sequence of bases in a gene codes for which amino acid are needed to build the protein.
• A group of 3 bases is a triplet. A triplet is a sequence of 3 bases that code for an amino acid.
• G1 and G2:

  • cell growth
  • new proteins synthesized
  • new organelles formed
• S phase:

  • DNA replication
  • Amount of DNA doubles
  • DNA is checked for errors
• Interphase:

  • is the phase between divisions , it is not a resting phase.
  • The DNA is unwound as chromatin so the genes are accessible for transcription
  • Cell growth and DNA replication all occur in this phase.
• Mutations happen randomly but the likelihood of one occurring can be increased by physical or chemical factors that affect DNA. these are called mutagens.