DNA and chromosomes

• What is a gene?


  A short section of DNA that contains a code for making a polypeptide and functional RNA. The code is a specific sequence of bases.
• What do polypeptides do?

  Make proteins and so genes determine the proteins of an organism.
• what is the locus?

  Location of a particular gene on a chromosome.
• What is an allele?


  one of a number of alternative forms of a gene. Most genes occur in two, occasionally more different forms.
• What’s a chromosom?


  In eukaryotic cells, nucleus stores DNA as chromose.
• What is a homologous pair?


  Pairs of matching chromosomes that are exactly the same size, exactly same genes but might contain different alleles.
• DNA storage in eukaryotes?

  • in the nucleus
  • chromosomes are linear in shape
  • tightly coil dna to fit the nucleus as chromosome, the dna is tightly wound around proteins called histones
  • complex of dna wrapped around histomes is called a nucleosome
• Where is DNA stored in prokaryotes?

  • free in cytoplasm
  • molecules are shorter and circular
  • not wrapped around histomes instead they supercoils to fit cell
• where else can DNA be found?

  Chloroplast and mitochondri- this storage of DNA is similar to prokaryotic dna storage