classification technologies

• Modern classification methods use genetic and biochemical data to examine relationships at a molecular level. This includes comparing DNA sequences, analysing proteins made by the animals, and testing immune responses.
• A phylogenetic tree is a diagram used by scientists to show how different species are related through evolution. It is similar to a family tree, with each branch point (called a node) representing a common ancestor. The length of the branches can sometimes indicate the amount of evolutionary change or time since divergence. The closer two species are on the tree, the more closely related they are genetically.
• DNA is the molecule that carries the genetic code for all living organisms. It is made of nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
• Closely related species will have similar DNA sequences. Scientists can:

  • extract and sequence DNA from different animals
  • compare the order of their bases

  The more similar the sequences, the more recently the species shared a common ancestor.
• what is the process of denaturation?

  the process of separating the two strands of a DNA double helix. during this, heat or chemical treatment break the hydrogen bonds, causing the strands (A-T and C-G) to unwind and separate.
• why is denaturation done?

  it makes it possible to compare DNA between different organisms
• what is DNA sequencing?

  the process of determining the exact order of the nucleotide bases in a DNA molecule
• label the nucleotide

  • phosphate
  • base (A,T,C,G)
  • sugar

  A) phosphate

  B) base

  C) sugar

  
• what is transcription?

  The DNA sequence of a gene is coped into RNA. in RNA the T is replaced with U. the resulting sequence has sets of three bases, each coding for a specific amino acid
• If two species have very similar amino acid sequences in the same protein, it indicates they share a close common ancestor.
• Proteins are large molecules made of smaller units called amino acids. The sequence of amino acids in a protein is determined by the organism's DNA.
• The immune system uses antibodies to detect foreign proteins, called antigens. Each species produces specific antigens. If antibodies from one species react with the antigens of another, it shows the proteins are similar. This is known as antigen-antibody cross-reactivity. The stronger the reaction, the more similar the proteins are, and the closer the relationship between the species.