1.7 + 1.8 - evolution and genomic sequencing

• define evolution?

  the changes in organisms over generations as a result of genomic variations
• Define natural selection?

  • the non random increase in the frequency of DNA sequences that increase survival
  • the non random reduction in the frequency of deleterious sequences
• what are selection pressures?

  any reason for organisms with certain phenotypes to have either a survival benefit or disadvantage
• what are the 3 selection pressures?

  • stabilising
  • directional
  • disruptive
• define stabilising selection?

  natural selection where an average phenotype is selected for and extremes of the phenotype range are selected against
• Define directional selection?

  Natural selection where one extreme of the phenotype range is selected for
• define disruptive selection?

  natural selection where two or more phenotypes are selected for
• What kind of selection pressure is this?

  stabilising selection

  
• what kind of selection is this?

  directional selection

  
• what kind of selection is this?

  disruptive selection

  
• define horizontal gene transfer?

  transfer of genes between individuals in the same generation
• define vertical gene transfer?

  genes are transferred from parent to offspring as a result of sexual or asexual reproduction
• Natural selection is more rapid in prokaryotes because they can exchange genetic material horizontally
• Define speciation?

  the generation of new biological species by evolution as a result of isolation, mutation and selection
• define species?

  a group of organisms that can interbreed to produce fertile offspring, and which does not normally breed with other groups
• Why are isolation barriers important?

  prevent gene flow between sub-populations during speciation
• allopatric speciation comes from geographical barriers
• Sympatric speciation comes from behavioural and ecological barriers
• In genomic sequencing, the sequence of nucleotide bases can be determined for individual genes and entire genomes
• How do you compare sequence data?

  computer and statistical analyses (bioinformatics)
• what does the comparison of genomes reveal?

  genes are highly conserved across different organisms
• what are the three domains of life?

  • Bacteria
  • archaea
  • eukaryotes
• What are two sources of evidence which can provide information used to products phylogenetic trees and molecular clocks?

  • sequence data
  • fossil evidence
• land plants are the most recently occurring evolutionary event
• Cells are the oldest occurring evolutionary event
• list the sequence of evolutionary events from oldest to newest?

  1. cells
  2. last universal ancestor
  3. prokaryotes
  4. photosynthetic organisms
  5. eukaryotes
  6. multicellularity
  7. animals
  8. vertebrates
  9. land plants
• Define phylogenetics?

  the study of evolutionary history and relationships
• What is sequence data used for?

  to show evolutionary relatedness between groups of organisms
• How can an individuals genome be analysed to predict the likelihood of developing certain diseases?

  • pharmacogenetics
  • personalised medicine