Unit 8

• name the six types of mutation

  substitution

  deletion

  addition

  duplication

  inversion

  translocation
• explain how a mutation can lead to a non functional protein

  change in the primary structure

  change in the tertiary structure

  hydrogen and ionic bonds change

  3D shape changes
• how does mutation of a tumour suppressor gene causes cancer

  DNA base sequence changes

  hypermethylation causes mutation

  tumour suppressor genes are not transcribed

  amino acid sequence changes

  causes rapid uncontrolled cell division
• how can methylation cause cancer

  methyl groups are added to the tumour suppressor gene - hypermethylation

  prevents the tumour suppressor gene from being transcribed

  causes rapid uncontrolled cell division

  the methyl group always attaches at a CpG site

  the enzyme DNA methyl transferase attaches the methyl group to cytosine
• define mutation

  a change in the DNA base sequence
• define mutagenic agent

  something that increases the rate of mutation
• what are stem cells?

  undifferentiated cells that can develop into other types of cell
• what are totipotent cells

  stem cells that can mature into any type of body cell

  only present in mammals in the first few cell divisions of an embryo

  zygotes are totipotent

  translate part of their DNA
• what are pluripotent cells

  cells become pluripotent after the first few cell divisions of an embryo

  stem cells that can differentiate into any type of body cell except the cells that make up the placenta
• what are multipotent cells

  stem cells able to differentiate into a few types of cell

  both red and white blood cells are formed from multipotent cells found in bone marrow
• what are unipotent cells

  can only differentiate into one type of cell

  e.g. cardiomyocytes
• What is formed when transcription factors bind with RNA polymerase, allowing it to bind to the site where transcription should start to begin RNA synthesis

  Transcription Initiation complex
• how does oestrogen act as a activator

  binds to an oestrogen receptor

  forms oestrogen-oestrogen receptor complex

  complex moved from the cytoplasm to the nucleus

  complex binds to RNA polymerase

  forms transcription initiation complex

  RNA polymerase active site is more complementary

  the TIC binds to the promoter region

  increases rate of transcription
• why does oestrogen only affect target cells

  only target cells have receptors complementary to oestrogen
• what is the CpG site

  when cytosine and guanine are next to each other in DNA

  they are linked by a phosphodiester bond
• describe the effects of acetylation of histone groups

  when histones are acetylated the chromatin is less condensed

  transcriptional machinery (e.g. enzymes ) can access DNA

  so genes are transcribed
• what enzyme removes acetyl groups from histone

  histone deacetylase
• what can cause cancer in tumour suppressor genes

  increased methylation

  decreased acetylation

  so the gene isn't transcribed
• what can cause cancer in proto-oncogenes

  increased acetylation

  decreased methylation

  so the gene is transcribed
• describe the polymerase chain reaction

  DNA is heated

  to break hydrogen bonds

  primers are added

  primers from complementary base pairs with specific base sequence

  nucleotides are added

  the solution is cooled

  primer allows DNA taq polymerase to bind
• What is the purpose of reverse transcriptase

  Forms DNA from RNA
• Define epigenetics

  Heritable changes in gene function with no change to DNA base sequence
• What is the purpose of gel electrophoresis 


  To separate DNA fragments based on their size / length and how negatively charged they are
• What is the purpose of DNA polymerase in PCR


  Joins adjacent DNA nucleotides

  forming phosphodiester bonds to produce DNA
• Why does DNA replication stop in the PCR

  There’s are no more primers and nucleotides left to bind
• what are acquired mutations

  mutations that occur in an individual after fertilisation
• what mutations can cause frame shift

  addition

  deletion

  duplication

  translocation
• what are stem cells

  undifferentiated cells that can divide by mitosis to replicate themselves indefinitely and specialise into other types of cells
• how induced pluripotent stem cells are produced

  obtain adult somatic cells from non-pluripotent cells

  add specific protein transcription factor associated with pluripotency to cells

  cells express genes associated with pluripotency

  transcription factors attach to promoter region of DNA to stimulate transcription

  cells are cultured and divide by mitosis
• what are transcription factors

  proteins which regulate transcription of specific target genes

  by binding to promoter region