Genetic Terms
  Allele - one alternative form of a given allelic pair; tall and dwarf are the alleles for the height of a
   pea plant; more than two alleles can exist for any specific gene, but only two of them will be
   found within any individual
  Allelic pair - the combination of two alleles which comprise the gene pair
  Homozygote - an individual which contains only one allele at the allelic pair; for example DD is
   homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene
   of interest
  Heterozygote - an individual which contains one of each member of the gene pair; for example
   the Dd heterozygote
  Genotype - the specific allelic combination for a certain gene or set of genes
  Backcross - the cross of an F1 hybrid to one of the homozygous parents; for pea plant height the
   cross would be Dd x DD or Dd x dd; most often, though a backcross is a cross to a fully recessive
   parent
  Testcross - the cross of any individual to a homozygous recessive parent; used to determine if the
   individual is homozygous dominant or heterozygous
  Monohybrid cross - a cross between parents that differ at a single gene pair (usually AA x aa)
  Monohybrid - the offspring of two parents that are homozygous for alternate alleles of a gene
   pair
  Dominance - the ability of one allele to express its phenotype at the expense of an alternate allele;
   the major form of interaction between alleles
Chromosomes
  The genes lie within the chromosomes.
  Humans have 23 pairs of these small thread-like structures in the nucleus of their cells.
  23 or half of the total 46 comes from the mother while the other 23 comes from the father.
  The chromosomes contain genes just like pages of a book.
  Some chromosomes may carry thousands of important genes while some may carry only a few.
  The chromosomes, and therefore the genes, are made up of the chemical substance called DNA
   (DeoxyriboNucleic Acid). The chromosomes are very long thin strands of DNA, coiled up tightly.
  At one point along their length, each chromosome has a constriction, called the centromere.
  The centromere divides the chromosomes into two ‘arms’: a long arm and a short arm.
  Chromosomes are numbered from 1 to 22 and these are common for both sexes and called
   autosomes.
  There are also two chromosomes that have been given the letters X and Y and termed sex
   chromosomes. The X chromosome is much larger than the Y chromosome.
Males and females
  Male have 46 chromosomes (44 autosomes plus an X and a Y chromosome) in their body cells
   and have half of these 22 autosomes plus an X or Y chromosome in their sperm cells.
  Female have 46 chromosomes (44 autosomes plus two copies of the X chromosome) in their body
   cells. They have half of this or 22 autosomes plus an X chromosome in their egg cells.
  When the egg joins with the sperm, the resultant baby has 46 chromosomes (with either an XX in
   a female baby or XY in a male baby).
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