DNA, genes and chromosomes

• Compare and contrast the structure of prokaryotic and eukaryotic DNA

  -Both have the same nucleotide structure

  -E DNA is long but P DNA is short

  -Both have phosphodiester bonds between nucleotides

  -E DNA is linear but P DNA is circular

  -Both are double-stranded

  -E DNA is wrapped around histones but P DNA is not associated with histones

  -E DNA has introns and exons, P DNA only has exons

  -The DNA in the matrix of mitochondria and the stroma of chloroplasts has the same structure as P DNA
• Define a gene

  A sequence of DNA bases that code for one polypeptide
• Define a locus

  A fixed position of a gene on a chromosome
• Define an allele

  A variation of a gene caused by random mutations
• Define universal

  The same triplets always code for the same amino acid in all organisms
• Define non-overlapping

  Each base is only ever part of one triplet
• Define degenerate

  Amino acids can be coded for by more than one triplet