Genes

• What are the 3 types of gene mutation?


  Substitution

  Deletion

  Insertion
• what is a substitution mutation?


  one base is changed with another one
• what is insertion mutation?


  adding one base to a sequence
• what is deletion mutation?


  one base is removed from a sequence
• how might a substitution mutation affect a protein?


  not very serious

  can only impact one amino acid
• how might insertion mutation affect a protein?


  very serious

  will affect all amino acids in the sequence
• how might deletion mutation affect a protein?


  Very serious

  Effects all amino acids in a sequence

  All the bases will shift back one
• How might a mutation be beneficial?

  Has a positive effect on an organism

  (ability to produce lactase in some organisms)
• how might a mutation be neutral?


  has no effect on an organisms likelihood to survive and reproduce

  (colour of eye)
• how might a mutation be harmful?


  has a negative effect on the organisms health and survival

  (cystic fibrosis)
• what is a gene mutation? where does it occur


  changes to the base sequence or quantity of DNA or section of DNA

  occurs during DNA replication
• what are the 2 types of mutations that can occur?


  small scale - gene mutation

  large scale - chromosome mutation
• what is chromosome mutation? where does it occur


  changes to the structure or number of whole chromosomes

  (occurs during meiosis)
• Function of the Lac operon, what is it known as?


  example of gene regulation in E.coli (and other prokaryotes) enabling the bacterium to use lactose as an energy source when glucose is unavailable.

  known as an inducible operon - can be turned off but can be activated under certain conditions
• what are the 4 stages that are involved in regulating gene expression?


  transcriptional regulation

  post - transcriptional regulation

  translational regulation

  post - translational regulation
• what is transcriptional regulation?and what is it controlled by?

  the DNA sequence of a gene is transcribed into mRNA.

  controlled by transcriptional factors
• what is post - transcriptional regulation?

  mRNA modified before translated into proteins.
• what is translational regulation?


  involves the regulation of mRNA translation into proteins by the ribosome
• what are transcriptional factors?


  proteins that bind to the DNA, which change the rate of transcription.
• what are the regions that the proteins (transcription factors) bind to on the DNA sequence called?


  promoter or operator
• what is the role of the promoter region?

  promotes the binding of RNA polymerase - helps activate transcription
• what is the role of the operator region?

  inhibits the binding of RNA polymerase
• what is the role of activators (regulatory gene)?

  increase transcription
• what is the role of repressors (regulatory gene)?

  decrease transcription
• what happens when lactose is not present?


  repressor protein is constantly produced and binds to the operator region. Prevents RNA polymerase binding to promoter and beginning transcription.
• what happens when lactose is present?

  lactose binds to the repressor protein causing it to change shape. it can no longer bind to the operator region. RNA polymerase can now bind to the promoter region and transcription of structural genes can start
• what does Beta-galactosidase do?


  breaks down lactose into galactose and glucose
• what does lactose permease do?


  makes the E.coli walls permeable to lactose
• what are the 3 structural genes?


  Lac Z, lac Y, lac A
• what is the function of structural proteins?


  code for useful proteins like enzymes