Ch10: Inheritance + variation

• Sexual reproduction - involves two parents

  Asexual reproduction - involves only one parent

  Chromosomes - thread like structures in cell nucleus, made of DNA.

  Gene - a length of DNA along a chromosome

  Variation - the way that members of the same species differ
• Humans have 46 chromosomes in each cell. When reproducing, cell division occurs so only one pair (23) of chromosomes go from each parent so the offspring has 46.
• Genotype - the genes an organism has. ex) genes for brown eyes

  Phenotype - the traits that can be seen in the organism. ex) brown eyes

  The organism can have the genes for something, ex) brown eyes, it doesn't mean the organism will have brown eyes. Environment plays a key role in the expression of the gene.