Genetic+Terminology

[] **DEFINITIONS**

 * Cell** is the smallest structural unit of living organisms that is able to grow and reproduce independently.


 * Chromosom**e**:**A threadlike strand of DNA and associated proteins that is in the nucleus of a cell. Chromosomes are basically like storage sacks for our dNA, and we have 46 chromosomes in each cell.


 * Gene:**the fundamental physical and functional unit of heredity OR Genes are like instruction manuals for our body, or like a recipe book which tells our bodies what they need to do.


 * Heredity:** The genetic transmission of characteristics from parent to offspring or The sum of characteristics and associated potentialities transmitted genetically to an individual organism.


 * Allele:** An alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. For example, the gene for seed shape in pea plants exists in two forms, one form or allele for round seed shape (R) and the other for wrinkled seed shape (r).


 * Dominant and Recessive**:to distinguish between dominant and recessive alleles, Dominant alleles are symbolised by capital letters and always come before recessive's(which are lower case letters and always come second to dominant alleles). there only needs to be 1 copy of a dominant allele to show a trait. there needs to be 2 recessive or lower case letter alleles to show the trait.


 * Genotype:** the allele you have for a gene,eg,Tt, are two alleles a person expresses for the tounge rolling gene. Tt is their genotype.


 * Phenotype**: the trait a person expresses as a result of their genotype, eg, A person may have a genotype of tt which means that their phenotype is non-tounge rolling.


 * Homozygos:** when you have two of the same alleles for the same gene,eg,TT or tt


 * Hetrozygous**: when you have two different alleles for the same gene ,eg Tt

DOUBLE HELIX:
The sugars in the backbone

The backbone of DNA is based on a repeated pattern of a sugar group and a phosphate group. The full name of DNA, deoxyribonucleic acid, gives you the name of the sugar present - deoxyribose.**