biology 12.1

• the scientific study of biological inheritance is called genetics
• Gregor Mendel was an Austrian monk who founded the modern science of genetics. He also studied the genetics of garden peas.
• Fertilization is the process in which male (sperm) & female (egg) cells fuse to form a zygote
• a trait is a specific characteristic that varies from one thing to another (plant height, seed color, eye color)
• a hybrid is an offspring of crosses between parents with different contrasting characteristics
• there are three generations; P: parents, F1: children, and F2: children of children
• genes are short stretches of DNA on chromosomes that code for proteins that determine traits and each individual has 2 copies of each gene
• alleles are alternative forms of a single gene (green & yellow seed alleles)
• the principle of dominance states that some alleles are dominant and others are recessive

  ♥ dominant alleles are always

  expressed (tall allele)

  ♥ recessive alleles are only expressed

  when no dominant allele is present

  (short allele)
• gametes are sex cells (eggs, sperm)

  • 2 alleles for each gene segregate from each other during gamete formation, each gamete carries only 1 allele for each gene

  • alleles are paired up again when gametes

  fuse during fertilization