DNA

• degenerate- some amino acids are encoded by more than one codon
• universal- the same 4 bases are used in the DNA of every organism
• non overlapping- each triplet code is separate from the other triplets in the chromosome
• Some genes encode functional RNA molecules instead of polypeptides. The RNA molecule that forms a part of ribosomes is called ribosomal RNA.
• An organism's antibodies can be isolated and mixed with another organisms proteins to see how many antibody-antigen complexes form. The more complexes form the more closely related they are
• mutagenic agents increase the rate at which mutations occur: UV radiation, chemicals and ionising radiation
• chromosome mutations can affect the number of chromosomes in a developing zygote. aneuploidy
• non disjunction is when chromosomes do not separate properly during meiosis
• there can be errors in the replication process that causes mutation
• role of meiosis


  produce haploid gametes

  increases genetic diversity
• crossing over


  in meiosis I, sections of DNA are swapped between chromosomes in a pair. produces new combinations of allele
• Independent segregation 


  the chromosomes in a homologous pair are separated in meiosis I in a random formation to produce two genetically different daughter cells. The combination of chromosomes in the two daughter cells is random.
• a large proportion of eukaryotic DNA is non coding
• there are regions of non coding multiple repeats in eukaryotic DNA. multiple repeats are random sequences repeated many times