DNA, genes and chromosomes

• what is DNA like in prokaryotic cells

  short, circular and not associated with proteins
• what is DNA like in eukaryotic cells

  very long, linear and are associated with proteins called histones
• what is the DNA like of mitochondria and chloroplasts

  short, circular and not associated with proteins like prokaryotic DNA
• what is a gene

  a base sequence of DNA that codes for the amino acid sequence of a polypeptide or functional RNA
• what is the locus of a gene

  where the gene occupies it’s fixed position on a particular DNA molecule
• what is a triplet

  a sequence of three DNA bases
• what does a triplet code for

  an amino acid
• what are the three features of the genetic code

  universal, non-overlapping, degenerate
• what does universal mean

  each triplet codes for the same amino acid in every organism
• what does non-overlapping mean

  each base sequence is only read once
• what does degenerate mean

  most amino acids are coded for by more than one triplet
• what are non-coding regions of nuclear DNA in eukaryotes called

  introns