DNA and chromosomes

• DNA in prokaryotes

  short, circular and not associated with proteinsfound in cytoplasm
• DNA in eukaryotes

  DNA molecules are very long, linear and associated with proteins called histones which forms chromosomesfound in nucleus
• What is a locus?

  the precise location of a gene on a chromosome
• What are exons?

  coding base sequences of DNA that code for a sequence of amino acids
• What are introns?

  non-coding base sequences
• What is the genome?

  the complete set of genes in an cell
• What is the proteome?

  The full range of proteins that a cell is able to produce
• What is a homologous pair of chromosomes?

  Two chromosomes that carry the same genes
• What is an allele?

  One of a number of alternative forms of a gene
• How is a DNA molecule formed into a chromosome ?

  1. DNA molecule coils and is combined with histones

  2) DNA-histone complex is coiled3) coils fold to form loops4) loops coil and pack together to form the chromosome