DNA and Genes

• DNA

  deoxyribonucleic acid, a double-stranded molecule twisted into a double helix made up of nucleotides
• Nucleotides

  Basic units of DNA molecule, composed of a sugar, a phosphate, and one of 4 DNA bases
• Nitrogen pairs


  Adenine, Thymine (A,T)Cytosine, Guanine (C,G)
• Genotype

  Genetic makeup of an organism; gene/allele combination an organism has.
• Phenotype

  An organism's physical appearance, or visible traits.
• Homozygous

  An organism that has two identical alleles for a trait
• Heterozygous

  An organism that has two different alleles for a trait
• George Mendel

  "Father of Genetics" studied hybrids using peas. Determined how traits were inherited.
• Law of Segregation

  Two alleles for each trait separate when gametes form; Parents pass only on allele for each trait to each offspring
• Law of Independent Assortment

  Genes for different traits are inherited independently of each other
• Dominant allele

  An allele whose trait always shows up in the organism, masking the other trait. Represented by a capital letter.
• Recessive allele

  Will show if dominant allele isn't present. Represented by lower case.
• Who is credited for the double helix model of DNA

  James Watson and Francis Crick