epigenetics

• what is meant by epigenetics


  this is the control of gene expression
• how does epigenetics control gene expression


  by modifying DNA or histone proteins but not affecting the DNA nucleotide sequence
• give an example of something that can cause an epigenetic change


  the environment
• are the nucleotide sequences affected by epigenetic changes


  no
• what does it mean by DNA being able to be modified post replication


  that this changes the ability for a gene to be transcribed in protein synthesis
• give two ways in which a gene can be modified epigenetically (other then environment)


  the addition of a methyl group and the modification of a histone protein
• how does the addition of a methyl group to a nitrogenous base act as an epigenetic change


  the methyl group will prevent the bases from being recognised
• when a methyl group is added to a nitrogenous base it wont be recognises , what does this mean


  the chances of the gene being expressed are reduced
• what is a histone protein

  this is a protein found in chromosomes, that organises DNA
• if a histone protein is more tightly coiled is it more or less likely to express the gene


  less likely
• if a histone protein is more loosely coiled is it more or less likely to express the gene


  more likely
• what is meant by modification of histone proteins


  this is to do with how tight the coil is around the protein
• are epigenetic changes limited to one cell in each tissue


  no