Make your own free website on Tripod.com

The Study of Genetics

Home | Site Map | What is Genetics? | Vocabulary | Mistakes in Genetics | Probability | Tie on Cloning and Genetics | Bibliography | CA Standards | About the Authors








Vocabulary

     Geneticists use complicated vocabulary. Since Genetics can't be explained without proper vocabulary, this page will define the vocabulary used throughout the site.
 
Heredity-The passing of traits from parent to offspring
     i.e. A blonde  haired wife gives birth to a blond haired son
 
Gene- A segment of DNA on a chromosome that codes for a specific trait
     i.e. This term is used for characteristics given to the children
 
Punnett Square- A chart that shows all of the possible combinations of alleles that can result from a genetic cross
     i.e. [Tt][tt]
           [Tt][Tt]
 
Alleles- A letter scientist use to represent a gene
     i.e. TT, Tt, which can stand for being tall; tt, which can stand for being short;
 
Dominant Allele- Alleles whose traits always show up in the organism when the allele is present
     i.e. Letter Combination: TT or Tt: Black hair over blonde hair, so the child will have black hair
 
Recessive Allele- An allele that is masked when a dominant allele is present
     i.e. Letter Combination: tt: Blonde hair over black hair, so the child will have blonde hair
 
Purebred- An organism that always produces offspring with the same form of traits as the parent
     i.e. A blond haired woman (tt)/ A black haired man (TT) *Notice that purebreds can have two capital or two lowercase letters*
 
Hybrid- An organism that has two different alleles for a trait
     i.e. A brunnette (Tt) *Notice that hybrids can have only a dominant trait, with one capital and lowercase letter*
 
Heterozygous- Having two different alleles for a trait *See Hybrid*
 
Homozygous- Having two identical alleles for a trait *See Purebred*
 
Trait- A characteristic that an organism can pass on to it's offspring through a gene *See Gene*
 
Phenotype- An organism's visible trait
     i.e. Black hair
Genotype- An organism's genetic makeup
     i.e. TT, which is the letter code for black hair
 
Codominance- A condition when neither dominant or recessive alleles are masked
     i.e. A brunnette and a black hair man have a child with black and brown hair
 
Meiosis- The process that occurs in sex cells by which the number of chromosomes are halved
     i.e. A man and a woman contribute their chromosomes to give birth, 23 from the man, and 23 from the woman will give a new set of 46 chromosomes
 
X chromosome- The sex cell that may determine the sex of the child (males) Or the sex cell that is fertilized with the male chromosome (females)
     i.e. Males and females both carry this chromosome
Y chromosome- The sex cell that determines the sex of the child
     i.e. Only males carry this chromosome
 
XY- When the female X chromosome is fertilized by the Y chromosome of the male
     i.e. The child is male
 
XX-When the female X chromosome is fertilized by the X chromosome of the male 
     i.e. The child is female
 
Nucleotide- The sequence of codes that make a gene