diversity of organisms

• Variation


  Differences that exist between organisms
• Causes of variation

  • Genes determine proteins an organism
  • Genetic variation generated by mutation in sexual reproduction
  • Environment determines resources needed to produce proteins, affecting gene expression
• Environmental factors that may generate variation

  • Temperature
  • Nutrient availability
  • Oxygen concentration
• Discontinuous variation

  Characteristics fall into distinct categories
• Continuous variation


  Characteristics can be measured incrementally on a scale
• Classification

  Process of putting organisms into groups
• Taxonomy


  The science of classification
• Taxonomist

  Scientist working in the field of taxonomy
• Taxon (plural taxa)


  Biological group an organism fits into
• Species


  The smallest taxonomic group
• what are morphological species 


  A species is a group of organisms that are morphologically unique
• who is Linnaeus


  18th century Swedish botanist, father of taxonomy
• Linnaeus developed the method of naming species that is used by scientists all over the world today
• what is the binomial system of nomenclature


  System of naming species according to their taxa, involving a two-part Latin name
• Conventions for writing binomial names


  • Genus begins with capital letter, species with lowercase
  • Binomial names should appear in italics when typed, or underlined when handwritten
  • First use should be full name, then genus can be abbreviated
• what are species


  a group of organisms that can interbreed to produce fertile offspring
• what is speciation


  The process by which one species gives rise to two or more new species
• Speciation can occur when a population becomes isolated from other populations of the same species due to living in a different area
• Genetic drift can also lead to speciation
• Once speciation has taken place, the two species can no longer breed to produce fertile offspring; they are reproductively isolated and are said to be separate species
• what is a diploid cell


  Cell that contains two complete sets of chromosomes
• what is a haploid cell


  Cell that contains one complete set of chromosomes
• During fertilisation, the nuclei of haploid gametes fuse together to form the nucleus of a diploid zygote
• Adult body cells are usually diploid cells
• what is fertilisation


  The nuclei of haploid gametes fuse together to form the nucleus of a diploid zygote
• Diploid number


  The number of chromosomes found in a diploid cell
• The diploid number must always be an even number
• Chromosome

  A strand of DNA, along which are sections known as genes
• Gene

  A section of DNA that codes for one polypeptide
• Chromosomes that have undergone DNA replication

  • Have the appearance of an 'X' shape, where the 'legs' of the X are made up of two strands of DNA attached at a region known as the centromere
• Humans have 46 chromosomes, while chimpanzees have 48
• Genome

  All of the genetic information in an organism
• Mitochondrial DNA and chloroplast DNA are included in the genome of eukaryotic cells
• In a prokaryote cell, plasmid DNA is included in the genome
• Humans share around 99.9 % of their DNA with other humans
• Humans share around 99 % of their DNA with chimpanzees
• DNA sequencing


  Determining the base sequence of DNA
• Phylogenetics


  The classification of species based on their evolutionary origins and relationships
• Advances in sequencing technology have allowed scientists to understand the true phylogeny of taxa
• Types of sequence data used to investigate evolutionary relationships


  • DNA
  • mRNA
  • Amino acids (of a protein)