DNA

• DNA


  chemical which all our genetic material is made up of
• what is a chromosome


  a coiled up piece of DNA that has genes that code for traits
• what is our 23rd chromosome

  sex chromosome
• women chromosomes


  XX
• men chromosomes


  XY
• genome


  entire set of genetic information that an organism carries in its DNA
• how can we use genomes

  to identify genes which cause diseases and trace the migrations of ancestors
• allele


  different forms of a gene
• homozygous


  two of the same alleles
• heterozygous


  an organism that has two different alleles for a trait
• recessive


  need two alleles for it to be expressed
• dominant


  an allele that is always expressed
• genotype


  genetic makeup of an organism
• phenotype


  physical characteristics of an organism